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:
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。