spring集成mybatis简单示例

亦凉 2022-03-01 15:08 273阅读 0赞

mybatis作为一个持久层框架，很少单独使用，一般都是和spring集成，和spring集成，mybatis-config.xml配置文件就不需要了，数据库相关配置全部交给spring，SqlSessionFactory就交给spring管理，同时需要一个数据源dataSource，最后再配置一个事务管理器就差不多了。这里仅仅介绍spring与mybatis的整合。

构建maven工程，添加相关依赖：

<dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
    <dependency>
    	<groupId>org.mybatis</groupId>
    	<artifactId>mybatis</artifactId>
    	<version>3.4.6</version>
    </dependency>
    <dependency>
    	<groupId>org.mybatis</groupId>
    	<artifactId>mybatis-spring</artifactId>
    	<version>1.3.2</version>
    </dependency>
    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-context-support</artifactId>
    	<version>4.3.13.RELEASE</version>
    </dependency>
    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-jdbc</artifactId>
    	<version>4.3.13.RELEASE</version>
    </dependency>
    
    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-test</artifactId>
    	<version>4.3.13.RELEASE</version>
    </dependency>
    <dependency>
    	<groupId>com.zaxxer</groupId>
    	<artifactId>HikariCP</artifactId>
    	<version>2.7.9</version>
    </dependency>
    <dependency>
    	<groupId>mysql</groupId>
    	<artifactId>mysql-connector-java</artifactId>
    	<version>5.1.46</version>
    </dependency>
    <dependency>
    	<groupId>org.aspectj</groupId>
    	<artifactId>aspectjweaver</artifactId>
    	<version>1.8.13</version>
    </dependency>
    </dependencies>

准备实体类和dao,service层接口：

User.java

package com.xxx.mybatis.domain;
    
    public class User {
    	private Integer id;
    	private String username;
    	private String password;
    	private Double balance;
    	public Integer getId() {
    		return id;
    	}
    	public void setId(Integer id) {
    		this.id = id;
    	}
    	public String getUsername() {
    		return username;
    	}
    	public void setUsername(String username) {
    		this.username = username;
    	}
    	public String getPassword() {
    		return password;
    	}
    	public void setPassword(String password) {
    		this.password = password;
    	}
    	
    	public void setBalance(Double balance) {
    		this.balance = balance;
    	}
    	
    	public Double getBalance() {
    		return balance;
    	}
    	
    	@Override
    	public String toString() {
    		return "User [id=" + id + ", username=" + username + ", password=" + password + "]";
    	}
    	
    }

UserDao.java

package com.xxx.mybatis.dao;
    import java.util.List;
    import java.util.Map;
    import com.xxx.mybatis.domain.User;
    public interface UserDao {
    	public User findById(Integer id);
    	public int insert(Map<String, Object> params);
    	public int update(Map<String, Object> params);
    	public int delete(Integer id);
    	public List<User> findAll();
    	public void updateBalance(Map<String, Object> params);
    }

UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
    <mapper namespace="com.xxx.mybatis.dao.UserDao">
        <select id="findById" resultType="com.xxx.mybatis.domain.User">
           select * from xx_user where id = #{id}
        </select>
        <insert id="insert">
        	insert into xx_user values(#{id},#{username},#{password})
        </insert>
        <update id="update">
        	update xx_user set 
        	username=#{username},
        	password = #{password}
        	where id = #{id}
        </update>
        <update id="updateBalance">
            update xx_user set
            balance = #{balance}
            where id = #{id}
        </update>
        <delete id="delete">
        	delete from xx_user where id = #{id}
        </delete>
        <select id="findAll" resultType="com.xxx.mybatis.domain.User">
        	select * from xx_user
        </select>
    </mapper>

UserService.java

package com.xxx.mybatis.service;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import com.xxx.mybatis.dao.UserDao;
    import com.xxx.mybatis.domain.User;
    @Service
    public class UserService {
    	@Autowired
    	private UserDao userDao;
    	public User findById(Integer id) {
    		return userDao.findById(id);
    	}
    	public int insert(Map<String,Object> params) {
    		return userDao.insert(params);
    	}
    	
    	public int update(Map<String, Object> params) {
    		return userDao.update(params);
    	}
    	
    	public int delete(Integer id) {
    		return userDao.delete(id);
    	}
    	
    	public List<User> findAll(){
    		return userDao.findAll();
    	}
    	
    	
    	public void transfer(Integer from,Integer to,double money){
    		User user = userDao.findById(from);
    		User user2 = userDao.findById(to);
    		user.setBalance(user.getBalance() - money);
    		Map<String,Object> params = new HashMap<String, Object>();
    		params.put("id", from);		
    		params.put("balance", user.getBalance());
    		userDao.updateBalance(params);
    		int i = 1/0;
    		System.out.println(i);
    		user2.setBalance(user2.getBalance()+money);
    		params.clear();
    		params.put("id", to);
    		params.put("balance", user2.getBalance());
    		userDao.updateBalance(params);
    	}
    }

jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&useSSL=false&characterEncoding=UTF-8
    jdbc.username=hadoop
    jdbc.password=hadoop

spring.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"
    	xmlns:tx="http://www.springframework.org/schema/tx"
    	xmlns:aop="http://www.springframework.org/schema/aop"
    	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
    		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
    		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
        
        <context:property-placeholder location="classpath*:jdbc.properties"/>
        
        <bean id="dataSource" class="com.zaxxer.hikari.HikariDataSource">
           <property name="driverClassName" value="${jdbc.driver}" />
           <property name="jdbcUrl" value="${jdbc.url}" />
           <property name="username" value="${jdbc.username}" />
           <property name="password" value="${jdbc.password}" />
        </bean>
        
        <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            <property name="dataSource" ref="dataSource" />
            <property name="mapperLocations"  value="classpath:com/xxx/mybatis/dao/*Mapper.xml"/>
        </bean>
        
        <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        	<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
        	<property name="basePackage" value="com.xxx.mybatis.dao"/>
        </bean>
        
        <context:component-scan base-package="com.xxx.mybatis" />
        <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
           <property name="dataSource" ref="dataSource" />
        </bean>
    
        <tx:advice id="tx-advice" transaction-manager="transactionManager">
            <tx:attributes>
                <tx:method name="find*" propagation="SUPPORTS" read-only="true"/>
                <tx:method name="update*" propagation="REQUIRED"/>
                <tx:method name="insert*" propagation="REQUIRED"/>
                <tx:method name="delete*" propagation="REQUIRED"/>
                <tx:method name="transfer*" propagation="REQUIRED"/>  
            </tx:attributes>
        </tx:advice>
        
        <aop:config>
            <aop:pointcut expression="execution(* com.xxx.mybatis.service.*.*(..))" id="point-cut"/>
            <aop:advisor pointcut-ref="point-cut" advice-ref="tx-advice"/>
        </aop:config>
    </beans>

至此，准备工作就做完了，我们准备一个单元测试类，测试我们集成的情况。

package com.xxx.mybatis;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.test.context.ContextConfiguration;
    import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
    import com.xxx.mybatis.domain.User;
    import com.xxx.mybatis.service.UserService;
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(locations= {"classpath:spring.xml"})
    public class JunitTest {
    	@Autowired
    	private UserService userService;
    	
    	@Test
    	public void select() {
    		User user = userService.findById(1);
    		System.out.println(user);
    	}
    	
    	@Test
    	public void transfer(){
    		userService.transfer(1, 2, 200);
    	}
    }

这里的单元测试很简单，就是测试一个查询方法，测试一个转账方法 。

这里如果查询方法没有问题，其他的service方法基本就可以跟着节奏来做，出不了大问题。spring与mybatis整合有个问题，就是事务管理，事务管理作用在service层，操作如果成功都成功，如果失败，全部回滚，这里准备了一个转账的测试用例，就是来测试事务的，这里的service方法里面，转账之后，模拟一个异常，这个异常会导致事务回滚，如果事务生效，那么转账操作是不会成功的，如果事务没有生效，那么转账过程，一个转出成功，第二个转入失败，这就会导致生产事故，所以这个测试示例可以检验我们的事务管理是否生效。

在spring配置文件中，需要注意一个地方，就是mapperScannerConfigurer这里，他需要一个属性为sqlSessionFactoryBeanName的属性，这个属性不能用ref来指定，必须使用value来指定，如下：

![20190322215249424.png][]

如果使用ref来指定，会报错：

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mapperScannerConfigurer' defined in class path resource \[spring.xml\]: Cannot resolve reference to bean 'sqlSessionFactory' while setting bean property 'sqlSessionFactoryBeanName'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource \[spring.xml\]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource \[spring.xml\]: Error setting property values; nested exception is org.springframework.beans.PropertyBatchUpdateException; nested PropertyAccessExceptions (1) are:  
PropertyAccessException 1: org.springframework.beans.MethodInvocationException: Property 'driverClassName' threw exception; nested exception is java.lang.RuntimeException: Failed to load driver class $\{jdbc.driver\} in either of HikariConfig class loader or Thread context classloader

映射文件与dao层接口放在一起，一个dao的接口方法名，对应一个mapper的子元素的ID。

到这里spring与mybatis简单整合基本结束，希望对初学的同学有帮助。

[20190322215249424.png]: /images/20220301/6cedffc3f3314960b3f01fc233d621db.png