jdbc学习笔记
jdbc学习笔记
Javaweb技术概览:
c/s架构: client server 客户端架构
b/s架构:browser server 浏览器架构
jdbc实现:
程序编写步骤:
MySQL 的jdbc驱动安装:
项目下新建一个lib文件夹,将驱动jar包导入,再点击jar包选择buildpath
获取数据库的连接;
package com.atguigu1.connection;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
import org.junit.Test;
public class ConnectionTest {
// 方式一:
@Test
public void testConnection1() throws SQLException {
// 获取Driver实现类对象
Driver driver = new com.mysql.jdbc.Driver();
// url:http://localhost:8080/gmall/keyboard.jpg
// jdbc:mysql:协议
// localhost:ip地址
// 3306:默认mysql的端口号
// test:test数据库
String url = "jdbc:mysql://localhost:3306/test";
// 将用户名和密码封装在Properties中
Properties info = new Properties();
info.setProperty("user", "root");
info.setProperty("password", "abc123");
Connection conn = driver.connect(url, info);
System.out.println(conn);
}
// 方式二:对方式一的迭代:在如下的程序中不出现第三方的api,使得程序具有更好的可移植性
@Test
public void testConnection2() throws Exception {
// 1.获取Driver实现类对象:使用反射
Class clazz = Class.forName("com.mysql.jdbc.Driver");
Driver driver = (Driver) clazz.newInstance();
// 2.提供要连接的数据库
String url = "jdbc:mysql://localhost:3306/test";
// 3.提供连接需要的用户名和密码
Properties info = new Properties();
info.setProperty("user", "root");
info.setProperty("password", "abc123");
// 4.获取连接
Connection conn = driver.connect(url, info);
System.out.println(conn);
}
// 方式三:使用DriverManager替换Driver
@Test
public void testConnection3() throws Exception {
// 1.获取Driver实现类的对象
Class clazz = Class.forName("com.mysql.jdbc.Driver");
Driver driver = (Driver) clazz.newInstance();
// 2.提供另外三个连接的基本信息:
String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "abc123";
// 注册驱动
DriverManager.registerDriver(driver);
// 获取连接
Connection conn = DriverManager.getConnection(url, user, password);
System.out.println(conn);
}
// 方式四:可以只是加载驱动,不用显示的注册驱动过了。
@Test
public void testConnection4() throws Exception {
// 1.提供三个连接的基本信息:
String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "abc123";
// 2.加载Driver
Class.forName("com.mysql.jdbc.Driver");
//相较于方式三,可以省略如下的操作:
// Driver driver = (Driver) clazz.newInstance();
// // 注册驱动
// DriverManager.registerDriver(driver);
//为什么可以省略上述操作呢?
/*
* 在mysql的Driver实现类中,声明了如下的操作:
* static {
try {
java.sql.DriverManager.registerDriver(new Driver());
} catch (SQLException E) {
throw new RuntimeException("Can't register driver!");
}
}
*/
// 3.获取连接
Connection conn = DriverManager.getConnection(url, user, password);
System.out.println(conn);
}
//方式五(final版):将数据库连接需要的4个基本信息声明在配置文件中,通过读取配置文件的方式,获取连接
/*
* 此种方式的好处?
* 1.实现了数据与代码的分离。实现了解耦
* 2.如果需要修改配置文件信息,可以避免程序重新打包。
*/
@Test
public void getConnection5() throws Exception{
//1.读取配置文件中的4个基本信息
InputStream is = ConnectionTest.class.getClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user = pros.getProperty("user");
String password = pros.getProperty("password");
String url = pros.getProperty("url");
String driverClass = pros.getProperty("driverClass");
//2.加载驱动
Class.forName(driverClass);
//3.获取连接
Connection conn = DriverManager.getConnection(url, user, password);
System.out.println(conn);
}
}
jdbc.properties:(配置文件声明在工程的src目录下)
user=root
password=abc123
url=jdbc:mysql://localhost:3306/test?rewriteBatchedStatements=true
driverClass=com.mysql.jdbc.Driver
Java与SQL对应数据类型转换表:
prepareStatement的操作:
增加操作:
package com.atguigu3.preparedstatement.crud;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Properties;
import org.junit.Test;
import com.atguigu1.connection.ConnectionTest;
import com.atguigu3.util.JDBCUtils;
// 向customers表中添加一条记录
@Test
public void testInsert() {
Connection conn = null;
PreparedStatement ps = null;
try {
// 1.读取配置文件中的4个基本信息
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user = pros.getProperty("user");
String password = pros.getProperty("password");
String url = pros.getProperty("url");
String driverClass = pros.getProperty("driverClass");
// 2.加载驱动
Class.forName(driverClass);
// 3.获取连接
conn = DriverManager.getConnection(url, user, password);
// System.out.println(conn);
//4.预编译sql语句,返回PreparedStatement的实例
String sql = "insert into customers(name,email,birth)values(?,?,?)";//?:占位符
ps = conn.prepareStatement(sql);
//5.填充占位符
ps.setString(1, "哪吒");
ps.setString(2, "nezha@gmail.com");
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
java.util.Date date = sdf.parse("1000-01-01");
ps.setDate(3, new Date(date.getTime()));
//6.执行操作
ps.execute();
} catch (Exception e) {
e.printStackTrace();
}finally{
//7.资源的关闭
try {
if(ps != null)
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
操作数据库的相关操作封装到utils里:
package com.atguigu3.util;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
/**
*
* @Description 操作数据库的工具类
* @author shkstart Email:shkstart@126.com
* @version
* @date 上午9:10:02
*
*/
public class JDBCUtils {
/**
*
* @Description 获取数据库的连接
* @author shkstart
* @date 上午9:11:23
* @return
* @throws Exception
*/
public static Connection getConnection() throws Exception {
// 1.读取配置文件中的4个基本信息
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user = pros.getProperty("user");
String password = pros.getProperty("password");
String url = pros.getProperty("url");
String driverClass = pros.getProperty("driverClass");
// 2.加载驱动
Class.forName(driverClass);
// 3.获取连接
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
}
/**
*
* @Description 关闭连接和Statement的操作
* @author shkstart
* @date 上午9:12:40
* @param conn
* @param ps
*/
public static void closeResource(Connection conn,Statement ps){
try {
if(ps != null)
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
*
* @Description 关闭资源操作
* @author shkstart
* @date 上午10:21:15
* @param conn
* @param ps
* @param rs
*/
public static void closeResource(Connection conn,Statement ps,ResultSet rs){
try {
if(ps != null)
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(rs != null)
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
再进行修改操作:
//修改customers表的一条记录
@Test
public void testUpdate(){
Connection conn = null;
PreparedStatement ps = null;
try {
//1.获取数据库的连接
conn = JDBCUtils.getConnection();
//2.预编译sql语句,返回PreparedStatement的实例
String sql = "update customers set name = ? where id = ?";
ps = conn.prepareStatement(sql);
//3.填充占位符
ps.setObject(1,"莫扎特");
ps.setObject(2, 18);
//4.执行
ps.execute();
} catch (Exception e) {
e.printStackTrace();
}finally{
//5.资源的关闭
JDBCUtils.closeResource(conn, ps);
}
}
}
实现通用增删改操作:
package com.atguigu3.preparedstatement.crud;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Properties;
import org.junit.Test;
import com.atguigu1.connection.ConnectionTest;
import com.atguigu3.util.JDBCUtils;
/*
* 使用PreparedStatement来替换Statement,实现对数据表的增删改操作
*
* 增删改;查
*
*
*/
public class PreparedStatementUpdateTest {
@Test
public void testCommonUpdate(){
// String sql = "delete from customers where id = ?";
// update(sql,3);
String sql = "update `order` set order_name = ? where order_id = ?";
update(sql,"DD","2");
}
//通用的增删改操作
public void update(String sql,Object ...args){//sql中占位符的个数与可变形参的长度相同!
Connection conn = null;
PreparedStatement ps = null;
try {
//1.获取数据库的连接
conn = JDBCUtils.getConnection();
//2.预编译sql语句,返回PreparedStatement的实例
ps = conn.prepareStatement(sql);
//3.填充占位符
for(int i = 0;i < args.length;i++){
ps.setObject(i + 1, args[i]);//小心参数声明错误!!
}
//4.执行
ps.execute();
} catch (Exception e) {
e.printStackTrace();
}finally{
//5.资源的关闭
JDBCUtils.closeResource(conn, ps);
}
}
针对customer表的查询操作;
@Test
public void testQuery1() {
Connection conn = null;
PreparedStatement ps = null;
ResultSet resultSet = null;
try {
conn = JDBCUtils.getConnection();
String sql = "select id,name,email,birth from customers where id = ?";
ps = conn.prepareStatement(sql);
ps.setObject(1, 1);
//执行,并返回结果集
resultSet = ps.executeQuery();
//处理结果集
if(resultSet.next()){//next():判断结果集的下一条是否有数据,如果有数据返回true,并指针下移;如果返回false,指针不会下移。
//获取当前这条数据的各个字段值
int id = resultSet.getInt(1);
String name = resultSet.getString(2);
String email = resultSet.getString(3);
Date birth = resultSet.getDate(4);
//方式一:
// System.out.println("id = " + id + ",name = " + name + ",email = " + email + ",birth = " + birth);
//方式二:
// Object[] data = new Object[]{id,name,email,birth};
//方式三:将数据封装为一个对象(推荐)
Customer customer = new Customer(id, name, email, birth);
System.out.println(customer);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
//关闭资源
JDBCUtils.closeResource(conn, ps, resultSet);
}
}
}
customer类:
package com.atguigu3.bean;
import java.sql.Date;
/*
* ORM编程思想 (object relational mapping)
* 一个数据表对应一个java类
* 表中的一条记录对应java类的一个对象
* 表中的一个字段对应java类的一个属性
*
*/
public class Customer {
private int id;
private String name;
private String email;
private Date birth;
public Customer() {
super();
}
public Customer(int id, String name, String email, Date birth) {
super();
this.id = id;
this.name = name;
this.email = email;
this.birth = birth;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Date getBirth() {
return birth;
}
public void setBirth(Date birth) {
this.birth = birth;
}
@Override
public String toString() {
return "Customer [id=" + id + ", name=" + name + ", email=" + email + ", birth=" + birth + "]";
}
}
针对customers表的通用查询:
public class CustomerForQuery {
@Test
public void testQueryForCustomers(){
String sql = "select id,name,birth,email from customers where id = ?";
Customer customer = queryForCustomers(sql, 13);
System.out.println(customer);
sql = "select name,email from customers where name = ?";
Customer customer1 = queryForCustomers(sql,"周杰伦");
System.out.println(customer1);
}
/**
*
* @Description 针对于customers表的通用的查询操作
* @author shkstart
* @throws Exception
* @date 上午10:23:40
*/
public Customer queryForCustomers(String sql,Object...args){
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JDBCUtils.getConnection();
ps = conn.prepareStatement(sql);
for(int i = 0;i < args.length;i++){
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
//获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
//通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
if(rs.next()){
Customer cust = new Customer();//rs有数据的条件下才造对象,避免浪费
//处理结果集一行数据中的每一个列
for(int i = 0;i <columnCount;i++){
//获取列值
Object columValue = rs.getObject(i + 1);
//获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
//给cust对象指定的columnName属性,赋值为columValue:通过反射
Field field = Customer.class.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(cust, columValue);
}
return cust;
}
} catch (Exception e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, ps, rs);
}
return null;
}
针对order表的查询操作:
package com.atguigu3.preparedstatement.crud;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import org.junit.Test;
import com.atguigu3.bean.Order;
import com.atguigu3.util.JDBCUtils;
/**
*
* @Description 针对于Order表的通用的查询操作
* @author shkstart Email:shkstart@126.com
* @version
* @date 上午10:43:58
*
*/
public class OrderForQuery {
/*
* 针对于表的字段名与类的属性名不相同的情况:
* 1. 必须声明sql时,使用类的属性名来命名字段的别名
* 2. 使用ResultSetMetaData时,需要使用getColumnLabel()来替换getColumnName(),
* 获取列的别名。
* 说明:如果sql中没有给字段其别名,getColumnLabel()获取的就是列名
*
*
*/
@Test
public void testOrderForQuery(){
String sql = "select order_id orderId,order_name orderName,order_date orderDate from `order` where order_id = ?";
Order order = orderForQuery(sql,1);
System.out.println(order);
}
/**
*
* @Description 通用的针对于order表的查询操作
* @author shkstart
* @date 上午10:51:12
* @return
* @throws Exception
*/
public Order orderForQuery(String sql,Object...args){
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JDBCUtils.getConnection();
ps = conn.prepareStatement(sql);
for(int i = 0;i < args.length;i++){
ps.setObject(i + 1, args[i]);
}
//执行,获取结果集
rs = ps.executeQuery();
//获取结果集的元数据
ResultSetMetaData rsmd = rs.getMetaData();
//获取列数
int columnCount = rsmd.getColumnCount();
if(rs.next()){
Order order = new Order();
for(int i = 0;i < columnCount;i++){
//获取每个列的列值:通过ResultSet
Object columnValue = rs.getObject(i + 1);
//通过ResultSetMetaData
//获取列的列名:getColumnName() --不推荐使用
//获取列的别名:getColumnLabel()
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
//通过反射,将对象指定名columnName的属性赋值为指定的值columnValue
Field field = Order.class.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(order, columnValue);
}
return order;
}
} catch (Exception e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, ps, rs);
}
return null;
}
@Test
public void testQuery1(){
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JDBCUtils.getConnection();
String sql = "select order_id,order_name,order_date from `order` where order_id = ?";
ps = conn.prepareStatement(sql);
ps.setObject(1, 1);
rs = ps.executeQuery();
if(rs.next()){
int id = (int) rs.getObject(1);
String name = (String) rs.getObject(2);
Date date = (Date) rs.getObject(3);
Order order = new Order(id, name, date);
System.out.println(order);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, ps, rs);
}
}
}
查询操作流程:
针对不同表的通用查询操作:
package com.atguigu3.preparedstatement.crud;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import com.atguigu3.bean.Customer;
import com.atguigu3.bean.Order;
import com.atguigu3.util.JDBCUtils;
/**
*
* @Description 使用PreparedStatement实现针对于不同表的通用的查询操作
* @author shkstart Email:shkstart@126.com
* @version
* @date 上午11:32:55
*
*/
public class PreparedStatementQueryTest {
@Test
public void testGetForList(){
String sql = "select id,name,email from customers where id < ?";
List<Customer> list = getForList(Customer.class,sql,12);
list.forEach(System.out::println);
String sql1 = "select order_id orderId,order_name orderName from `order`";
List<Order> orderList = getForList(Order.class, sql1);
orderList.forEach(System.out::println);
}
public <T> List<T> getForList(Class<T> clazz,String sql, Object... args){
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JDBCUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
// 获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
// 通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
//创建集合对象
ArrayList<T> list = new ArrayList<T>();
while (rs.next()) {
T t = clazz.newInstance();
// 处理结果集一行数据中的每一个列:给t对象指定的属性赋值
for (int i = 0; i < columnCount; i++) {
// 获取列值
Object columValue = rs.getObject(i + 1);
// 获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
// 给t对象指定的columnName属性,赋值为columValue:通过反射
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columValue);
}
list.add(t);
}
return list;
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(conn, ps, rs);
}
return null;
}
@Test
public void testGetInstance(){
String sql = "select id,name,email from customers where id = ?";
Customer customer = getInstance(Customer.class,sql,12);
System.out.println(customer);
String sql1 = "select order_id orderId,order_name orderName from `order` where order_id = ?";
Order order = getInstance(Order.class, sql1, 1);
System.out.println(order);
}
/**
*
* @Description 针对于不同的表的通用的查询操作,返回表中的一条记录
* @author shkstart
* @date 上午11:42:23
* @param clazz
* @param sql
* @param args
* @return
*/
public <T> T getInstance(Class<T> clazz,String sql, Object... args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JDBCUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
// 获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
// 通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
if (rs.next()) {
T t = clazz.newInstance();
// 处理结果集一行数据中的每一个列
for (int i = 0; i < columnCount; i++) {
// 获取列值
Object columValue = rs.getObject(i + 1);
// 获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
// 给t对象指定的columnName属性,赋值为columValue:通过反射
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columValue);
}
return t;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(conn, ps, rs);
}
return null;
}
}
操作BlLOB类型数据:
实例:
package com.atguigu5.blob;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.junit.Test;
import com.atguigu3.bean.Customer;
import com.atguigu3.util.JDBCUtils;
/**
*
* @Description 测试使用PreparedStatement操作Blob类型的数据
* @author shkstart Email:shkstart@126.com
* @version
* @date 下午4:08:58
*
*/
public class BlobTest {
//向数据表customers中插入Blob类型的字段
@Test
public void testInsert() throws Exception{
Connection conn = JDBCUtils.getConnection();
String sql = "insert into customers(name,email,birth,photo)values(?,?,?,?)";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setObject(1,"袁浩");
ps.setObject(2, "yuan@qq.com");
ps.setObject(3,"1992-09-08");
FileInputStream is = new FileInputStream(new File("girl.jpg"));
ps.setBlob(4, is);
ps.execute();
JDBCUtils.closeResource(conn, ps);
}
//查询数据表customers中Blob类型的字段
@Test
public void testQuery(){
Connection conn = null;
PreparedStatement ps = null;
InputStream is = null;
FileOutputStream fos = null;
ResultSet rs = null;
try {
conn = JDBCUtils.getConnection();
String sql = "select id,name,email,birth,photo from customers where id = ?";
ps = conn.prepareStatement(sql);
ps.setInt(1, 21);
rs = ps.executeQuery();
if(rs.next()){
// 方式一:
// int id = rs.getInt(1);
// String name = rs.getString(2);
// String email = rs.getString(3);
// Date birth = rs.getDate(4);
//方式二:
int id = rs.getInt("id");
String name = rs.getString("name");
String email = rs.getString("email");
Date birth = rs.getDate("birth");
Customer cust = new Customer(id, name, email, birth);
System.out.println(cust);
//将Blob类型的字段下载下来,以文件的方式保存在本地
Blob photo = rs.getBlob("photo");
is = photo.getBinaryStream();
fos = new FileOutputStream("zhangyuhao.jpg");
byte[] buffer = new byte[1024];
int len;
while((len = is.read(buffer)) != -1){
fos.write(buffer, 0, len);
}
}
} catch (Exception e) {
e.printStackTrace();
}finally{
try {
if(is != null)
is.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
if(fos != null)
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
JDBCUtils.closeResource(conn, ps, rs);
}
}
}
批量插入操作及优化:
package com.atguigu5.blob;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.junit.Test;
import com.atguigu3.util.JDBCUtils;
/*
* 使用PreparedStatement实现批量数据的操作
*
* update、delete本身就具有批量操作的效果。
* 此时的批量操作,主要指的是批量插入。使用PreparedStatement如何实现更高效的批量插入?
*
* 题目:向goods表中插入20000条数据
* CREATE TABLE goods(
id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(25)
);
* 方式一:使用Statement
* Connection conn = JDBCUtils.getConnection();
* Statement st = conn.createStatement();
* for(int i = 1;i <= 20000;i++){
* String sql = "insert into goods(name)values('name_" + i + "')";
* st.execute(sql);
* }
*
*/
public class InsertTest {
//批量插入的方式二:使用PreparedStatement
@Test
public void testInsert1() {
Connection conn = null;
PreparedStatement ps = null;
try {
long start = System.currentTimeMillis();
conn = JDBCUtils.getConnection();
String sql = "insert into goods(name)values(?)";
ps = conn.prepareStatement(sql);
for(int i = 1;i <= 20000;i++){
ps.setObject(1, "name_" + i);
ps.execute();
}
long end = System.currentTimeMillis();
System.out.println("花费的时间为:" + (end - start));//20000:83065
} catch (Exception e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, ps);
}
}
/*
* 批量插入的方式三:
* 1.addBatch()、executeBatch()、clearBatch()
* 2.mysql服务器默认是关闭批处理的,我们需要通过一个参数,让mysql开启批处理的支持。
* ?rewriteBatchedStatements=true 写在配置文件的url后面
* 3.使用更新的mysql 驱动:mysql-connector-java-5.1.37-bin.jar
*/
@Test
public void testInsert2() {
Connection conn = null;
PreparedStatement ps = null;
try {
long start = System.currentTimeMillis();
conn = JDBCUtils.getConnection();
String sql = "insert into goods(name)values(?)";
ps = conn.prepareStatement(sql);
for(int i = 1;i <= 1000000;i++){
ps.setObject(1, "name_" + i);
//1."攒"sql
ps.addBatch();
if(i % 500 == 0){
//2.执行batch
ps.executeBatch();
//3.清空batch
ps.clearBatch();
}
}
long end = System.currentTimeMillis();
System.out.println("花费的时间为:" + (end - start));//20000:83065 -- 565
} catch (Exception e) { //1000000:16086
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, ps);
}
}
//批量插入的方式四:设置连接不允许自动提交数据
@Test
public void testInsert3() {
Connection conn = null;
PreparedStatement ps = null;
try {
long start = System.currentTimeMillis();
conn = JDBCUtils.getConnection();
//设置不允许自动提交数据
conn.setAutoCommit(false);
String sql = "insert into goods(name)values(?)";
ps = conn.prepareStatement(sql);
for(int i = 1;i <= 1000000;i++){
ps.setObject(1, "name_" + i);
//1."攒"sql
ps.addBatch();
if(i % 500 == 0){
//2.执行batch
ps.executeBatch();
//3.清空batch
ps.clearBatch();
}
}
//提交数据
conn.commit();
long end = System.currentTimeMillis();
System.out.println("花费的时间为:" + (end - start));//20000:83065 -- 565
} catch (Exception e) { //1000000:16086 -- 5114
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, ps);
}
}
}
数据库事务:
考虑数据库的增删改操作:
package com.atguigu1.transaction;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import org.junit.Test;
import com.atguigu1.util.JDBCUtils;
/*
* 1.什么叫数据库事务?
* 事务:一组逻辑操作单元,使数据从一种状态变换到另一种状态。
* > 一组逻辑操作单元:一个或多个DML操作。
*
* 2.事务处理的原则:保证所有事务都作为一个工作单元来执行,即使出现了故障,都不能改变这种执行方式。
* 当在一个事务中执行多个操作时,要么所有的事务都被提交(commit),那么这些修改就永久地保存
* 下来;要么数据库管理系统将放弃所作的所有修改,整个事务回滚(rollback)到最初状态。
*
* 3.数据一旦提交,就不可回滚
*
* 4.哪些操作会导致数据的自动提交?
* >DDL操作一旦执行,都会自动提交。
* >set autocommit = false 对DDL操作失效
* >DML默认情况下,一旦执行,就会自动提交。
* >我们可以通过set autocommit = false的方式取消DML操作的自动提交。
* >默认在关闭连接时,会自动的提交数据
*/
public class TransactionTest {
//******************未考虑数据库事务情况下的转账操作**************************
/*
* 针对于数据表user_table来说:
* AA用户给BB用户转账100
*
* update user_table set balance = balance - 100 where user = 'AA';
* update user_table set balance = balance + 100 where user = 'BB';
*/
@Test
public void testUpdate(){
String sql1 = "update user_table set balance = balance - 100 where user = ?";
update(sql1, "AA");
//模拟网络异常
System.out.println(10 / 0);
String sql2 = "update user_table set balance = balance + 100 where user = ?";
update(sql2, "BB");
System.out.println("转账成功");
}
// 通用的增删改操作---version 1.0
public int update(String sql, Object... args) {// sql中占位符的个数与可变形参的长度相同!
Connection conn = null;
PreparedStatement ps = null;
try {
// 1.获取数据库的连接
conn = JDBCUtils.getConnection();
// 2.预编译sql语句,返回PreparedStatement的实例
ps = conn.prepareStatement(sql);
// 3.填充占位符
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);// 小心参数声明错误!!
}
// 4.执行
return ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
//修改其为自动提交数据
//主要针对于使用数据库连接池的使用
try {
conn.setAutoCommit(true);
} catch (SQLException e) {
e.printStackTrace();
}
// 5.资源的关闭
JDBCUtils.closeResource(conn, ps);
}
return 0;
}
//********************考虑数据库事务后的转账操作*********************
@Test
public void testUpdateWithTx() {
Connection conn = null;
try {
conn = JDBCUtils.getConnection();
System.out.println(conn.getAutoCommit());//true
//1.取消数据的自动提交
conn.setAutoCommit(false);
String sql1 = "update user_table set balance = balance - 100 where user = ?";
update(conn,sql1, "AA");
//模拟网络异常
System.out.println(10 / 0);
String sql2 = "update user_table set balance = balance + 100 where user = ?";
update(conn,sql2, "BB");
System.out.println("转账成功");
//2.提交数据
conn.commit();
} catch (Exception e) {
e.printStackTrace();
//3.回滚数据
try {
conn.rollback();
} catch (SQLException e1) {
e1.printStackTrace();
}
}finally{
JDBCUtils.closeResource(conn, null);
}
}
// 通用的增删改操作---version 2.0 (考虑上事务)
public int update(Connection conn,String sql, Object... args) {// sql中占位符的个数与可变形参的长度相同!
PreparedStatement ps = null;
try {
// 1.预编译sql语句,返回PreparedStatement的实例
ps = conn.prepareStatement(sql);
// 2.填充占位符
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);// 小心参数声明错误!!
}
// 3.执行
return ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
// 4.资源的关闭
JDBCUtils.closeResource(null, ps);
}
return 0;
}
//*****************************************************
@Test
public void testTransactionSelect() throws Exception{
Connection conn = JDBCUtils.getConnection();
//获取当前连接的隔离级别
System.out.println(conn.getTransactionIsolation());
//设置数据库的隔离级别:
conn.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
//取消自动提交数据
conn.setAutoCommit(false);
String sql = "select user,password,balance from user_table where user = ?";
User user = getInstance(conn, User.class, sql, "CC");
System.out.println(user);
}
@Test
public void testTransactionUpdate() throws Exception{
Connection conn = JDBCUtils.getConnection();
//取消自动提交数据
conn.setAutoCommit(false);
String sql = "update user_table set balance = ? where user = ?";
update(conn, sql, 5000,"CC");
Thread.sleep(15000);
System.out.println("修改结束");
}
//通用的查询操作,用于返回数据表中的一条记录(version 2.0:考虑上事务)
public <T> T getInstance(Connection conn,Class<T> clazz,String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
// 获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
// 通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
if (rs.next()) {
T t = clazz.newInstance();
// 处理结果集一行数据中的每一个列
for (int i = 0; i < columnCount; i++) {
// 获取列值
Object columValue = rs.getObject(i + 1);
// 获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
// 给t对象指定的columnName属性,赋值为columValue:通过反射
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columValue);
}
return t;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(null, ps, rs);
}
return null;
}
}
事务的ACID属性及四种隔离级别:
抽象的操作所有数据库表的DAO:
package com.atguigu2.dao;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import com.atguigu1.util.JDBCUtils;
/*
* DAO: data(base) access object
* 封装了针对于数据表的通用的操作
*/
public abstract class BaseDAO {
// 通用的增删改操作---version 2.0 (考虑上事务)
public int update(Connection conn, String sql, Object... args) {// sql中占位符的个数与可变形参的长度相同!
PreparedStatement ps = null;
try {
// 1.预编译sql语句,返回PreparedStatement的实例
ps = conn.prepareStatement(sql);
// 2.填充占位符
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);// 小心参数声明错误!!
}
// 3.执行
return ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
// 4.资源的关闭
JDBCUtils.closeResource(null, ps);
}
return 0;
}
// 通用的查询操作,用于返回数据表中的一条记录(version 2.0:考虑上事务)
public <T> T getInstance(Connection conn, Class<T> clazz, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
// 获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
// 通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
if (rs.next()) {
T t = clazz.newInstance();
// 处理结果集一行数据中的每一个列
for (int i = 0; i < columnCount; i++) {
// 获取列值
Object columValue = rs.getObject(i + 1);
// 获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
// 给t对象指定的columnName属性,赋值为columValue:通过反射
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columValue);
}
return t;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(null, ps, rs);
}
return null;
}
// 通用的查询操作,用于返回数据表中的多条记录构成的集合(version 2.0:考虑上事务)
public <T> List<T> getForList(Connection conn, Class<T> clazz, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
// 获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
// 通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
// 创建集合对象
ArrayList<T> list = new ArrayList<T>();
while (rs.next()) {
T t = clazz.newInstance();
// 处理结果集一行数据中的每一个列:给t对象指定的属性赋值
for (int i = 0; i < columnCount; i++) {
// 获取列值
Object columValue = rs.getObject(i + 1);
// 获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
// 给t对象指定的columnName属性,赋值为columValue:通过反射
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columValue);
}
list.add(t);
}
return list;
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(null, ps, rs);
}
return null;
}
//用于查询特殊值的通用的方法
public <E> E getValue(Connection conn,String sql,Object...args){
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(sql);
for(int i = 0;i < args.length;i++){
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
if(rs.next()){
return (E) rs.getObject(1);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(null, ps, rs);
}
return null;
}
}
根据对于特定表的功能操作定义对应接口(规范):
package com.atguigu2.dao;
import java.sql.Connection;
import java.sql.Date;
import java.util.List;
import com.atguigu2.bean.Customer;
/*
* 此接口用于规范针对于customers表的常用操作
*/
public interface CustomerDAO {
/**
*
* @Description 将cust对象添加到数据库中
* @author shkstart
* @date 上午11:00:27
* @param conn
* @param cust
*/
void insert(Connection conn,Customer cust);
/**
*
* @Description 针对指定的id,删除表中的一条记录
* @author shkstart
* @date 上午11:01:07
* @param conn
* @param id
*/
void deleteById(Connection conn,int id);
/**
*
* @Description 针对内存中的cust对象,去修改数据表中指定的记录
* @author shkstart
* @date 上午11:02:14
* @param conn
* @param cust
*/
void update(Connection conn,Customer cust);
/**
*
* @Description 针对指定的id查询得到对应的Customer对象
* @author shkstart
* @date 上午11:02:59
* @param conn
* @param id
*/
Customer getCustomerById(Connection conn,int id);
/**
*
* @Description 查询表中的所有记录构成的集合
* @author shkstart
* @date 上午11:03:50
* @param conn
* @return
*/
List<Customer> getAll(Connection conn);
/**
*
* @Description 返回数据表中的数据的条目数
* @author shkstart
* @date 上午11:04:44
* @param conn
* @return
*/
Long getCount(Connection conn);
/**
*
* @Description 返回数据表中最大的生日
* @author shkstart
* @date 上午11:05:33
* @param conn
* @return
*/
Date getMaxBirth(Connection conn);
}
customerDAOimpl的实现:
package com.atguigu2.dao;
import java.sql.Connection;
import java.sql.Date;
import java.util.List;
import com.atguigu2.bean.Customer;
public class CustomerDAOImpl extends BaseDAO implements CustomerDAO{
@Override
public void insert(Connection conn, Customer cust) {
String sql = "insert into customers(name,email,birth)values(?,?,?)";
update(conn, sql,cust.getName(),cust.getEmail(),cust.getBirth());
}
@Override
public void deleteById(Connection conn, int id) {
String sql = "delete from customers where id = ?";
update(conn, sql, id);
}
@Override
public void update(Connection conn, Customer cust) {
String sql = "update customers set name = ?,email = ?,birth = ? where id = ?";
update(conn, sql,cust.getName(),cust.getEmail(),cust.getBirth(),cust.getId());
}
@Override
public Customer getCustomerById(Connection conn, int id) {
String sql = "select id,name,email,birth from customers where id = ?";
Customer customer = getInstance(conn,Customer.class, sql,id);
return customer;
}
@Override
public List<Customer> getAll(Connection conn) {
String sql = "select id,name,email,birth from customers";
List<Customer> list = getForList(conn, Customer.class, sql);
return list;
}
@Override
public Long getCount(Connection conn) {
String sql = "select count(*) from customers";
return getValue(conn, sql);
}
@Override
public Date getMaxBirth(Connection conn) {
String sql = "select max(birth) from customers";
return getValue(conn, sql);
}
}
对于DAO中用泛型获取反射的一些升级:
package com.atguigu3.dao;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import com.atguigu1.util.JDBCUtils;
/*
* DAO: data(base) access object
* 封装了针对于数据表的通用的操作
*/
public abstract class BaseDAO<T> {
private Class<T> clazz = null;
// public BaseDAO(){
//
// }
{
//获取当前BaseDAO的子类继承的父类中的泛型
Type genericSuperclass = this.getClass().getGenericSuperclass();
ParameterizedType paramType = (ParameterizedType) genericSuperclass;
Type[] typeArguments = paramType.getActualTypeArguments();//获取了父类的泛型参数
clazz = (Class<T>) typeArguments[0];//泛型的第一个参数
}
// 通用的增删改操作---version 2.0 (考虑上事务)
public int update(Connection conn, String sql, Object... args) {// sql中占位符的个数与可变形参的长度相同!
PreparedStatement ps = null;
try {
// 1.预编译sql语句,返回PreparedStatement的实例
ps = conn.prepareStatement(sql);
// 2.填充占位符
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);// 小心参数声明错误!!
}
// 3.执行
return ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
// 4.资源的关闭
JDBCUtils.closeResource(null, ps);
}
return 0;
}
// 通用的查询操作,用于返回数据表中的一条记录(version 2.0:考虑上事务)
public T getInstance(Connection conn, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
// 获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
// 通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
if (rs.next()) {
T t = clazz.newInstance();
// 处理结果集一行数据中的每一个列
for (int i = 0; i < columnCount; i++) {
// 获取列值
Object columValue = rs.getObject(i + 1);
// 获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
// 给t对象指定的columnName属性,赋值为columValue:通过反射
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columValue);
}
return t;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(null, ps, rs);
}
return null;
}
// 通用的查询操作,用于返回数据表中的多条记录构成的集合(version 2.0:考虑上事务)
public List<T> getForList(Connection conn, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
// 获取结果集的元数据 :ResultSetMetaData
ResultSetMetaData rsmd = rs.getMetaData();
// 通过ResultSetMetaData获取结果集中的列数
int columnCount = rsmd.getColumnCount();
// 创建集合对象
ArrayList<T> list = new ArrayList<T>();
while (rs.next()) {
T t = clazz.newInstance();
// 处理结果集一行数据中的每一个列:给t对象指定的属性赋值
for (int i = 0; i < columnCount; i++) {
// 获取列值
Object columValue = rs.getObject(i + 1);
// 获取每个列的列名
// String columnName = rsmd.getColumnName(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
// 给t对象指定的columnName属性,赋值为columValue:通过反射
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columValue);
}
list.add(t);
}
return list;
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(null, ps, rs);
}
return null;
}
//用于查询特殊值的通用的方法
public <E> E getValue(Connection conn,String sql,Object...args){
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(sql);
for(int i = 0;i < args.length;i++){
ps.setObject(i + 1, args[i]);
}
rs = ps.executeQuery();
if(rs.next()){
return (E) rs.getObject(1);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(null, ps, rs);
}
return null;
}
}
数据库连接池:
1.c3p0数据库连接池的配置:
将解压的文件夹下lib中的jar文件导入项目中(方法同上)
具体使用可参考:
package com.atguigu4.connection;
import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;
import org.junit.Test;
import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.mchange.v2.c3p0.DataSources;
public class C3P0Test {
//方式一:
@Test
public void testGetConnection() throws Exception{
//获取c3p0数据库连接池
ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setDriverClass( "com.mysql.jdbc.Driver" );
cpds.setJdbcUrl( "jdbc:mysql://localhost:3306/test" );
cpds.setUser("root");
cpds.setPassword("abc123");
//通过设置相关的参数,对数据库连接池进行管理:
//设置初始时数据库连接池中的连接数
cpds.setInitialPoolSize(10);
Connection conn = cpds.getConnection();
System.out.println(conn);
//销毁c3p0数据库连接池
// DataSources.destroy( cpds );
}
//方式二:使用配置文件
@Test
public void testGetConnection1() throws SQLException{
ComboPooledDataSource cpds = new ComboPooledDataSource("hellc3p0");
Connection conn = cpds.getConnection();
System.out.println(conn);
}
}
xml文件:
<?xml version="1.0" encoding="UTF-8"?>
-<c3p0-config>
-<named-config name="hellc3p0">
<!-- 提供获取连接的4个基本信息 -->
<property name="driverClass">com.mysql.jdbc.Driver</property>
<!--使用的是本地localhost 3306 可以直接省略 -->
<property name="jdbcUrl">jdbc:mysql:///test</property>
<property name="user">root</property>
<property name="password">abc123</property>
<!-- 进行数据库连接池管理的基本信息 -->
<!-- 当数据库连接池中的连接数不够时,c3p0一次性向数据库服务器申请的连接数 -->
<property name="acquireIncrement">5</property>
<!-- c3p0数据库连接池中初始化时的连接数 -->
<property name="initialPoolSize">10</property>
<!-- c3p0数据库连接池维护的最少连接数 -->
<property name="minPoolSize">10</property>
<!-- c3p0数据库连接池维护的最多的连接数 -->
<property name="maxPoolSize">100</property>
<!-- c3p0数据库连接池最多维护的Statement的个数 -->
<property name="maxStatements">50</property>
<!-- 每个连接中可以最多使用的Statement的个数 -->
<property name="maxStatementsPerConnection">2</property>
</named-config>
</c3p0-config>
DBCP数据库连接池:
配置:
导入DBCP:
导入DBCP pool:
然后添加path......
实现代码:
package com.atguigu4.connection;
import java.io.File;
import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
import org.junit.Test;
public class DBCPTest {
/**
*
* @Description 测试DBCP的数据库连接池技术
* @author shkstart
* @throws SQLException
* @date 下午3:20:50
*/
//方式一:不推荐
@Test
public void testGetConnection() throws SQLException{
//创建了DBCP的数据库连接池
BasicDataSource source = new BasicDataSource();
//设置基本信息
source.setDriverClassName("com.mysql.jdbc.Driver");
source.setUrl("jdbc:mysql:///test");
source.setUsername("root");
source.setPassword("abc123");
//还可以设置其他涉及数据库连接池管理的相关属性:
source.setInitialSize(10);
source.setMaxActive(10);
//。。。
Connection conn = source.getConnection();
System.out.println(conn);
}
//方式二:推荐:使用配置文件
@Test
public void testGetConnection1() throws Exception{
Properties pros = new Properties();
//方式1:
// InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("dbcp.properties");
//方式2:
FileInputStream is = new FileInputStream(new File("src/dbcp.properties"));
pros.load(is);
DataSource source = BasicDataSourceFactory.createDataSource(pros);
Connection conn = source.getConnection();
System.out.println(conn);
}
}
一些配置属性:
Druid数据库连接池技术:
配置参考同上;
package com.atguigu4.connection;
import java.io.InputStream;
import java.sql.Connection;
import java.util.Properties;
import javax.sql.DataSource;
import org.junit.Test;
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;
public class DruidTest {
@Test
public void getConnection() throws Exception{
Properties pros = new Properties();
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("druid.properties");
pros.load(is);
DataSource source = DruidDataSourceFactory.createDataSource(pros);
Connection conn = source.getConnection();
System.out.println(conn);
}
}
druid.properties:
url=jdbc:mysql:///test
username=root
password=abc123
driverClassName=com.mysql.jdbc.Driver
initialSize=10
maxActive=10
将以上数据库连接打包到util中:
package com.atguigu4.util;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
import org.apache.commons.dbutils.DbUtils;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class JDBCUtils {
/**
*
* @Description 获取数据库的连接
* @author shkstart
* @date 上午9:11:23
* @return
* @throws Exception
*/
public static Connection getConnection() throws Exception {
// 1.读取配置文件中的4个基本信息
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
Properties pros = new Properties();
pros.load(is);
String user = pros.getProperty("user");
String password = pros.getProperty("password");
String url = pros.getProperty("url");
String driverClass = pros.getProperty("driverClass");
// 2.加载驱动
Class.forName(driverClass);
// 3.获取连接
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
}
/**
*
* @Description 使用C3P0的数据库连接池技术
* @author shkstart
* @date 下午3:01:25
* @return
* @throws SQLException
*/
//数据库连接池只需提供一个即可。
private static ComboPooledDataSource cpds = new ComboPooledDataSource("hellc3p0");
public static Connection getConnection1() throws SQLException{
Connection conn = cpds.getConnection();
return conn;
}
/**
*
* @Description 使用DBCP数据库连接池技术获取数据库连接
* @author shkstart
* @date 下午3:35:25
* @return
* @throws Exception
*/
//创建一个DBCP数据库连接池
private static DataSource source;
static{
try {
Properties pros = new Properties();
FileInputStream is = new FileInputStream(new File("src/dbcp.properties"));
pros.load(is);
source = BasicDataSourceFactory.createDataSource(pros);
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConnection2() throws Exception{
Connection conn = source.getConnection();
return conn;
}
/**
* 使用Druid数据库连接池技术
*/
private static DataSource source1;
static{
try {
Properties pros = new Properties();
InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("druid.properties");
pros.load(is);
source1 = DruidDataSourceFactory.createDataSource(pros);
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConnection3() throws SQLException{
Connection conn = source1.getConnection();
return conn;
}
/**
*
* @Description 关闭连接和Statement的操作
* @author shkstart
* @date 上午9:12:40
* @param conn
* @param ps
*/
public static void closeResource(Connection conn,Statement ps){
try {
if(ps != null)
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
*
* @Description 关闭资源操作
* @author shkstart
* @date 上午10:21:15
* @param conn
* @param ps
* @param rs
*/
public static void closeResource(Connection conn,Statement ps,ResultSet rs){
try {
if(ps != null)
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(rs != null)
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
*
* @Description 使用dbutils.jar中提供的DbUtils工具类,实现资源的关闭
* @author shkstart
* @date 下午4:53:09
* @param conn
* @param ps
* @param rs
*/
public static void closeResource1(Connection conn,Statement ps,ResultSet rs){
// try {
// DbUtils.close(conn);
// } catch (SQLException e) {
// e.printStackTrace();
// }
// try {
// DbUtils.close(ps);
// } catch (SQLException e) {
// e.printStackTrace();
// }
// try {
// DbUtils.close(rs);
// } catch (SQLException e) {
// e.printStackTrace();
// }
DbUtils.closeQuietly(conn);
DbUtils.closeQuietly(ps);
DbUtils.closeQuietly(rs);
}
}
详细参数配置:
apache-DButils实现CURD操作:
使用QueryRunner实现增加与查询操作:
package com.atguigu5.dbutils;
import java.sql.Connection;
import java.sql.Date;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import org.junit.Test;
import com.atguigu2.bean.Customer;
import com.atguigu4.util.JDBCUtils;
/*
* commons-dbutils 是 Apache 组织提供的一个开源 JDBC工具类库,封装了针对于数据库的增删改查操作
*
*/
public class QueryRunnerTest {
//测试插入
@Test
public void testInsert() {
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "insert into customers(name,email,birth)values(?,?,?)";
int insertCount = runner.update(conn, sql, "蔡徐坤","caixukun@126.com","1997-09-08");
System.out.println("添加了" + insertCount + "条记录");
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
//测试查询
/*
* BeanHander:是ResultSetHandler接口的实现类,用于封装表中的一条记录。
*/
@Test
public void testQuery1(){
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "select id,name,email,birth from customers where id = ?";
BeanHandler<Customer> handler = new BeanHandler<>(Customer.class);
Customer customer = runner.query(conn, sql, handler, 23);
System.out.println(customer);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
/*
* BeanListHandler:是ResultSetHandler接口的实现类,用于封装表中的多条记录构成的集合。
*/
@Test
public void testQuery2() {
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "select id,name,email,birth from customers where id < ?";
BeanListHandler<Customer> handler = new BeanListHandler<>(Customer.class);
List<Customer> list = runner.query(conn, sql, handler, 23);
list.forEach(System.out::println);
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
/*
* MapHander:是ResultSetHandler接口的实现类,对应表中的一条记录。
* 将字段及相应字段的值作为map中的key和value
*/
@Test
public void testQuery3(){
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "select id,name,email,birth from customers where id = ?";
MapHandler handler = new MapHandler();
Map<String, Object> map = runner.query(conn, sql, handler, 23);
System.out.println(map);
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
/*
* MapListHander:是ResultSetHandler接口的实现类,对应表中的多条记录。
* 将字段及相应字段的值作为map中的key和value。将这些map添加到List中
*/
@Test
public void testQuery4(){
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "select id,name,email,birth from customers where id < ?";
MapListHandler handler = new MapListHandler();
List<Map<String, Object>> list = runner.query(conn, sql, handler, 23);
list.forEach(System.out::println);
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
/*
* ScalarHandler:用于查询特殊值
*/
@Test
public void testQuery5(){
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "select count(*) from customers";
ScalarHandler handler = new ScalarHandler();
Long count = (Long) runner.query(conn, sql, handler);
System.out.println(count);
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
@Test
public void testQuery6(){
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "select max(birth) from customers";
ScalarHandler handler = new ScalarHandler();
Date maxBirth = (Date) runner.query(conn, sql, handler);
System.out.println(maxBirth);
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
/*
* 自定义ResultSetHandler的实现类
*/
@Test
public void testQuery7(){
Connection conn = null;
try {
QueryRunner runner = new QueryRunner();
conn = JDBCUtils.getConnection3();
String sql = "select id,name,email,birth from customers where id = ?";
ResultSetHandler<Customer> handler = new ResultSetHandler<Customer>(){
@Override
public Customer handle(ResultSet rs) throws SQLException {
// System.out.println("handle");
// return null;
// return new Customer(12, "成龙", "Jacky@126.com", new Date(234324234324L));
if(rs.next()){
int id = rs.getInt("id");
String name = rs.getString("name");
String email = rs.getString("email");
Date birth = rs.getDate("birth");
Customer customer = new Customer(id, name, email, birth);
return customer;
}
return null;
}
};//资源关闭
Customer customer = runner.query(conn, sql, handler,23);
System.out.println(customer);
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtils.closeResource(conn, null);
}
}
}