Java中JDBC的使用

1、注册驱动

1 Driver driver = new com.nysql.jdbc.Driver();
2 DriverMabeger.registerDriver(driver);

 

2、获取数据库链接

1 String url = "jdbc:mysql://127.0.0.1:3306/bd171";
2 String user = "root";
3 String passwd = "root";
4 Connection connection = DriverManager.getConnection(url,user,passwd);

 

3、获取数据库操作对象

1 Statement statement = connection.createStatement();

 

4、执行sql语句

1 String sql = "";
2 ResultSet resultSet = statement.excuteQuery(sql);

 

5、处理查询结果

1  while(resultSet.next())
2 {
3      int id = resultSet.getInt("id");
4      String last_name = resultSet.getString("last_name");
5      souble salary = resultSet.getDouble("salary");
6 }

 

6、关闭连接

//关闭链接是从最底层开始关闭
if(resultSet != null)
{
    resultSet.close();    
}

if(statement!= null)
{
    statement.close();    
}

if(connection!= null)
{
    connection.close();    
}

 

实现代码

 1 import java.sql.*;
 2 
 3 /*
 4 * 第六步：关闭资源
 5 * */
 6 public class JDBCTest06 {
 7     public static void main(String[] args) {
 8         Driver driver = null;
 9         Connection connection = null;
10         Statement statement = null;
11         ResultSet resultSet = null;
12         try {
13             //1 注册驱动
14             driver = new com.mysql.jdbc.Driver();
15             DriverManager.registerDriver(driver);
16 
17             //2 获取数据库链接
18             String url = "jdbc:mysql://127.0.0.1:3306/bd171";
19             String user = "root";
20             String passwd = "root";
21             connection = DriverManager.getConnection(url, user, passwd);
22 
23             //3 获取数据库操作对象
24             statement = connection.createStatement();
25 
26             //4 执行sql语句
27             String sql = "select id,last_name,salary from s_emp";
28             resultSet = statement.executeQuery(sql);
29 
30             //5 处理查询结果
31             while (resultSet.next()){
32                 int id = resultSet.getInt("id");
33                 String last_name = resultSet.getString("last_name");
34                 double salary = resultSet.getDouble("salary");
35                 System.out.println(id+" "+last_name+" "+salary);
36             }
37         }catch (Exception e){
38             e.printStackTrace();
39         }finally {
40             //6 关闭资源 --> 从最底层开始关闭
41             if (resultSet != null)
42             {
43                 try {
44                     resultSet.close();
45                 } catch (SQLException throwables) {
46                     throwables.printStackTrace();
47                 }
48             }
49 
50             if (statement != null)
51             {
52                 try {
53                     statement.close();
54                 } catch (SQLException throwables) {
55                     throwables.printStackTrace();
56                 }
57             }
58 
59             if (connection != null)
60             {
61                 try {
62                     connection.close();
63                 } catch (SQLException throwables) {
64                     throwables.printStackTrace();
65                 }
66             }
67 
68         }
69     }
70 }

 

posted @ 2021-02-23 10:06  陌上尘如玉  阅读(64)  评论(0)    收藏  举报