SpringBoot使用JdbcTemplate
JdbcTemplate的设计目的是为不同类型的HJDBC操作提供模板方法，每个模板方法都能控制整个数据访问的过程。
常用方法：
- execute：可以用于执行任何的SQL语句，一般用于执行DDL语句；
- update和batchUpdate：用于执行新增、修改、删除等语句，batch是批量的意思；
- query和queryForObject：用于查询相关语句；
- call：用于执行存储过程、函数等语句。
JdbcTemplate对应的配置信息如下：
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-jdbc -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
完整的pom配置如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.cjs</groupId>
<artifactId>springjdbctemplatetest</artifactId>
<version>1.0-SNAPSHOT</version>
<name>springjdbctemplatetest</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.6.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!-- Web依赖 -->
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-web -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- Mysql依赖 -->
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<!-- JDBC依赖 -->
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-jdbc -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
</dependencies>
<build>
<pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
<plugins>
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.0.0</version>
</plugin>
<!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.7.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.20.1</version>
</plugin>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>
省略application.properties和Bean类的创建，直接给出XXXDaoImpl类，
package com.cjs.dao.impl;
import com.cjs.bean.User;
import com.cjs.dao.UserDao;
import com.mysql.jdbc.Statement;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.PreparedStatementCreator;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.support.GeneratedKeyHolder;
import org.springframework.jdbc.support.KeyHolder;
import org.springframework.stereotype.Repository;
import javax.annotation.Resource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;
@Repository
public class UserDaoImpl implements UserDao {
@Resource
private JdbcTemplate jdbcTemplate;//注入Jdbc模板核心对象
@Override
public int insertUser() {
String sql = "insert into tb_users(loginname, username, password)"
+ " values(?,?,?),(?,?,?),(?,?,?)";
Object[] args = new Object[]{"swk","Tom", "123456","zbj", "Jean","123456","ts","Jimmy","123456"};
return jdbcTemplate.update(sql, args);//update(String sql, Object[] obj{}),第一个参数时sql语句，第二个参数是填充sql语句的？参数，依次填入
}
@Override
public User selectByUserName(String username) {
String sql = "select * from tb_users where username = ?";
RowMapper<User> rowMapper = new BeanPropertyRowMapper<>(User.class);//设置返回数据类型
User user = jdbcTemplate.queryForObject(sql, new Object[]{username}, rowMapper);
return user;
}
@Override
public User selectUserById(int id) {
String sql = "select * from tb_users where id = ?";
RowMapper<User> rowMapper = new BeanPropertyRowMapper<>(User.class);
User user = jdbcTemplate.queryForObject(sql, new Object[]{id}, rowMapper);
return user;
}
@Override
public List<User> findAll() {
String sql = "select * from tb_users";
RowMapper<User> rowMapper = new BeanPropertyRowMapper<>(User.class);
return jdbcTemplate.query(sql, rowMapper);
}
@Override
public void delete(Integer id) {
String sql = "delete from tb_users where id=?";
jdbcTemplate.update(sql, new Object[]{id});
}
@Override
public void update(User user) {
String sql = "update tb_users set username=?, loginname=? where id=?";
jdbcTemplate.update(sql, new Object[]{user.getUsername(), user.getLoginname(), user.getId()});
}
@Override
public User insertGetKey(final User user) {//获取新插入数据的id
KeyHolder holder = new GeneratedKeyHolder();
jdbcTemplate.update(new PreparedStatementCreator() {
@Override
public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {
String sql = "insert into tb_users(username, loginname, password) values(?,?,?)";
PreparedStatement ps = connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);
ps.setString(1,user.getUsername());
ps.setString(2,user.getLoginname());
ps.setString(3,user.getPassword());
return ps;
}
}, holder);
int newUserId = holder.getKey().intValue();
user.setId(newUserId);
return user;
}
}
Biz层和Controller也不是这里重点，上面已经将JdbcTemplate的使用说清楚了，因为文中所说那几个常用的方法有很多重载，有些人喜欢用三个参数的，xxx(String sql, Object[] obj, RowMapper<T> rm);不管需不需要填充sql语句参数，都写上，看个人习惯而已。
