Spring快速整合Mybatis

MyBatis是一個優秀的持久層框架，Spring則是廣泛使用的Java應用框架。可以將兩者整合可以充分發揮各自的優勢。

1、Spring整合MyBatis的基本配置

添加依賴：

<dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.3.10</version>
</dependency>
<!-- Spring JDBC支持 -->
<dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>5.3.10</version>
</dependency>
<!-- MyBatis核心 -->
<dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.7</version>
</dependency>
<!-- MyBatis-Spring整合包 -->
<dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>2.0.6</version>
</dependency>
<!-- 數據庫驅動 -->
<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.26</version>
</dependency>

Spring配置文件：
創建Spring配置文件applicationContext.xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttps://www.springframework.org/schema/context/spring-context.xsd"><!-- 配置數據源 --><bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"><property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/mybatis_db?useSSL=false&amp;serverTimezone=UTC"/><property name="username" value="root"/><property name="password" value="password"/></bean><!-- 配置SqlSessionFactory --><bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"><property name="dataSource" ref="dataSource"/><!-- 指定MyBatis配置文件 --><property name="configLocation" value="classpath:mybatis-config.xml"/><!-- 指定mapper.xml文件位置 --><property name="mapperLocations" value="classpath:mapper/*.xml"/></bean><!-- 配置Mapper掃描器 --><bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"><property name="basePackage" value="com.example.mapper"/><property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/></bean><!-- 開啟注解掃描 --><context:component-scan base-package="com.example"/>
</beans>

MyBatis配置文件：
創建mybatis-config.xml：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><settings><setting name="mapUnderscoreToCamelCase" value="true"/></settings><typeAliases><package name="com.example.entity"/></typeAliases>
</configuration>

2、基本的CRUD操作

創建實體類：

package com.example.entity;
public class User {private Long id;private String username;private String password;private String email;// 省略getter和setter方法// 省略toString方法
}

創建Mapper接口：

package com.example.mapper;
import com.example.entity.User;
import java.util.List;
public interface UserMapper {int insert(User user);int update(User user);int deleteById(Long id);User selectById(Long id);List<User> selectAll();
}

創建Mapper XML文件：
在resources/mapper目錄下創建UserMapper.xml：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.mapper.UserMapper"><insert id="insert" parameterType="User" useGeneratedKeys="true" keyProperty="id">INSERT INTO user(username, password, email)VALUES(#{username}, #{password}, #{email})</insert><update id="update" parameterType="User">UPDATE userSET username=#{username}, password=#{password}, email=#{email}WHERE id=#{id}</update><delete id="deleteById" parameterType="long">DELETE FROM user WHERE id=#{id}</delete><select id="selectById" parameterType="long" resultType="User">SELECT * FROM user WHERE id=#{id}</select><select id="selectAll" resultType="User">SELECT * FROM user</select>
</mapper>

創建Service層：

package com.example.service;
import com.example.entity.User;
import com.example.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserService {@Autowiredprivate UserMapper userMapper;public int addUser(User user) {return userMapper.insert(user);}public int modifyUser(User user) {return userMapper.update(user);}public int removeUser(Long id) {return userMapper.deleteById(id);}public User getUserById(Long id) {return userMapper.selectById(id);}public List<User> getAllUsers() {return userMapper.selectAll();}
}

測試類：

import com.example.entity.User;
import com.example.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.List;
public class Application {public static void main(String[] args) {ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");UserService userService = context.getBean(UserService.class);// 添加用戶User user = new User();user.setUsername("testUser");user.setPassword("123456");user.setEmail("test@example.com");userService.addUser(user);System.out.println("添加用戶成功，ID: " + user.getId());// 查詢用戶User dbUser = userService.getUserById(user.getId());System.out.println("查詢用戶: " + dbUser);// 更新用戶dbUser.setEmail("newemail@example.com");userService.modifyUser(dbUser);System.out.println("更新用戶成功");// 查詢所有用戶List<User> users = userService.getAllUsers();System.out.println("所有用戶:");users.forEach(System.out::println);// 刪除用戶userService.removeUser(user.getId());System.out.println("刪除用戶成功");}
}

3、動態SQL和分頁查詢

擴展Mapper接口：
// 在UserMapper接口中添加

List<User> selectByCondition(@Param("username") String username, @Param("email") String email);List<User> selectByPage(@Param("offset") int offset, @Param("pageSize") int pageSize);

擴展Mapper XML：

<!-- 在UserMapper.xml中添加 -->
<select id="selectByCondition" resultType="User">SELECT * FROM user<where><if test="username != null and username != ''">AND username LIKE CONCAT('%', #{username}, '%')</if><if test="email != null and email != ''">AND email LIKE CONCAT('%', #{email}, '%')</if></where>
</select>
<select id="selectByPage" resultType="User">SELECT * FROM user LIMIT #{offset}, #{pageSize}
</select>

擴展Service：
// 在UserService中添加

public List<User> getUsersByCondition(String username, String email) {return userMapper.selectByCondition(username, email);
}
public List<User> getUsersByPage(int pageNum, int pageSize) {int offset = (pageNum - 1) * pageSize;return userMapper.selectByPage(offset, pageSize);
}

測試動態SQL和分頁：
// 在Application的main方法中添加測試代碼

System.out.println("條件查詢:");
List<User> conditionUsers = userService.getUsersByCondition("test", null);
conditionUsers.forEach(System.out::println);
System.out.println("分頁查詢(第1頁，每頁2條):");
List<User> pageUsers = userService.getUsersByPage(1, 2);
pageUsers.forEach(System.out::println);

4、事務管理

修改Spring配置

在applicationContext.xml中添加事務配置：
<!-- 事務管理器 -->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"><property name="dataSource" ref="dataSource"/>
</bean>
<!-- 開啟注解驅動的事務管理 -->
<tx:annotation-driven transaction-manager="transactionManager"/>

創建事務性Service方法：

@Transactional
public void transferEmail(Long fromId, Long toId, String newEmail) {User fromUser = userMapper.selectById(fromId);User toUser = userMapper.selectById(toId);if(fromUser == null || toUser == null) {throw new RuntimeException("用戶不存在");}// 將fromUser的email設置為newEmailfromUser.setEmail(newEmail);userMapper.update(fromUser);// 模擬異常if(newEmail.contains("error")) {throw new RuntimeException("測試事務回滾");}// 將toUser的email也設置為newEmailtoUser.setEmail(newEmail);userMapper.update(toUser);
}

測試事務：

try {userService.transferEmail(1L, 2L, "transaction@example.com");System.out.println("事務操作成功");
} catch (Exception e) {System.out.println("事務操作失敗: " + e.getMessage());
}
try {userService.transferEmail(1L, 2L, "error@example.com");
} catch (Exception e) {System.out.println("事務回滾測試: " + e.getMessage());
}