Spring 中使用 JdbcTemplate 连接操作 MySQL

JdbcTemplate 是 Spring 利用 Aop 思想封装的 JDBC 操作工具。

准备工作

引入依赖

创建一个新项目，添加如下依赖：

<dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.1.9.RELEASE</version></dependency><!-- DataBase Begin --><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>5.1.9.RELEASE</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.17</version></dependency><!-- DataBase Over -->

创建数据库

CREATE DATABASE /*!32312 IF NOT EXISTS*/`test01` /*!40100 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci */ /*!80016 DEFAULT ENCRYPTION=\'N\' */;USE `test01`;/*Table structure for table `user` */DROP TABLE IF EXISTS `user`;CREATE TABLE `user` (`id` int(11) NOT NULL AUTO_INCREMENT,`username` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,`address` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

创建实体类

public class User {private Integer id;private String username;private String address;@Overridepublic String toString() {return "User{" +"id=" + id +", username=\'" + username + \'\\\'\' +", address=\'" + address + \'\\\'\' +\'}\';}// 省略 get/set 方法}

Java 配置

提供一个配置类，在配置类中配置

JdbcTemplate

@Configurationpublic class JdbcConfig {@BeanDataSource dataSource() {DriverManagerDataSource dataSource = new DriverManagerDataSource();dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");dataSource.setUsername("root");dataSource.setPassword("123456");dataSource.setUrl("jdbc:mysql:///test01");return dataSource;}@BeanJdbcTemplate jdbcTemplate() {return new JdbcTemplate(dataSource());}}

这里，提供两个 Bean，一个是

DataSource

的 Bean，另一个是

JdbcTemplate

的 Bean，

JdbcTemplate

的配置非常容易，只需要 new 一个 Bean 出来，然后配置一下 DataSource 就可以。

public class Main {private JdbcTemplate jdbcTemplate;@Beforepublic void before() {AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(JdbcConfig.class);jdbcTemplate = ctx.getBean(JdbcTemplate.class);}@Testpublic void insert() {jdbcTemplate.update("insert into user (username,address) values (?,?);", "antonio", "www.antoniopeng.com");}@Testpublic void update() {jdbcTemplate.update("update user set username=? where id=?", "antonio", 1);}@Testpublic void delete() {jdbcTemplate.update("delete from user where id=?", 2);}@Testpublic void select() {User user = jdbcTemplate.queryForObject("select * from user where id=?", new BeanPropertyRowMapper<User>(User.class), 1);System.out.println(user);}}

在查询时，如果使用了

BeanPropertyRowMapper

，要求查出来的字段必须和 Bean 的属性名一一对应。如果不一样，则不要使用

BeanPropertyRowMapper

，此时需要自定义

RowMapper

或者给查询的字段取别名。

1. 给查询出来的列取别名：

   @Testpublic void select2() {User user = jdbcTemplate.queryForObject("select id,username as name,address from user where id=?", new BeanPropertyRowMapper<User>(User.class), 1);System.out.println(user);}

2. 自定义 RowMapper

   @Testpublic void select3() {User user = jdbcTemplate.queryForObject("select * from user where id=?", new RowMapper<User>() {public User mapRow(ResultSet resultSet, int i) throws SQLException {int id = resultSet.getInt("id");String username = resultSet.getString("username");String address = resultSet.getString("address");User u = new User();u.setId(id);u.setName(username);u.setAddress(address);return u;}}, 1);System.out.println(user);}

查询多条记录，方式如下：

@Testpublic void select4() {List<User> list = jdbcTemplate.query("select * from user", new BeanPropertyRowMapper<>(User.class));System.out.println(list);}

XML 配置

以上配置，也可以通过 XML 文件来实现。通过 XML 文件实现只是提供 JdbcTemplate 实例，剩下的代码还是 Java 代码，就是 JdbcConfig 被 XML 文件代替而已。

<bean class="org.springframework.jdbc.datasource.DriverManagerDataSource" id="dataSource"><property name="username" value="root"/><property name="password" value="123"/><property name="url" value="jdbc:mysql:///test01?serverTimezone=Asia/Shanghai"/><property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/></bean><bean class="org.springframework.jdbc.core.JdbcTemplate" id="jdbcTemplate"><property name="dataSource" ref="dataSource"/></bean>

配置完成后，加载该配置文件，并启动：

public class Main {private JdbcTemplate jdbcTemplate;@Beforepublic void before() {ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");jdbcTemplate = ctx.getBean(JdbcTemplate.class);}@Testpublic void insert() {jdbcTemplate.update("insert into user (username,address) values (?,?);", "javaboy", "www.javaboy.org");}@Testpublic void update() {jdbcTemplate.update("update user set username=? where id=?", "javaboy123", 1);}@Testpublic void delete() {jdbcTemplate.update("delete from user where id=?", 2);}@Testpublic void select() {User user = jdbcTemplate.queryForObject("select * from user where id=?", new BeanPropertyRowMapper<User>(User.class), 1);System.out.println(user);}@Testpublic void select4() {List<User> list = jdbcTemplate.query("select * from user", new BeanPropertyRowMapper<>(User.class));System.out.println(list);}@Testpublic void select2() {User user = jdbcTemplate.queryForObject("select id,username as name,address from user where id=?", new BeanPropertyRowMapper<User>(User.class), 1);System.out.println(user);}@Testpublic void select3() {User user = jdbcTemplate.queryForObject("select * from user where id=?", new RowMapper<User>() {public User mapRow(ResultSet resultSet, int i) throws SQLException {int id = resultSet.getInt("id");String username = resultSet.getString("username");String address = resultSet.getString("address");User u = new User();u.setId(id);u.setName(username);u.setAddress(address);return u;}}, 1);System.out.println(user);}}

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