mybatis学习笔记(17)-spring和mybatis整合
mybatis学习笔记(17)-spring和mybatis整合
标签： mybatis spring
- mybatis学习笔记17-spring和mybatis整合
- 整合思路
- 整合环境
- sqlSessionFactory
- 原始dao开发和spring整合后
- mapper代理开发
- 遇到的问题
本文主要将如何将spring和mybatis整合，只是作简单的示例，没有使用Maven构建。并展示mybatis与spring整合后如何进行原始dao开发和mapper代理开发。
整合思路
需要spring通过单例方式管理SqlSessionFactory。
spring和mybatis整合生成代理对象，使用SqlSessionFactory创建SqlSession。（spring和mybatis整合自动完成）
持久层的mapper都需要由spring进行管理。
整合环境
创建一个新的java工程（接近实际开发的工程结构）
jar包：
- mybatis3.2.7的jar包
- spring3.2.0的jar包
- mybatis和spring的整合包：早期ibatis和spring整合是由spring官方提供，mybatis和spring整合由mybatis提供。
sqlSessionFactory
在applicationContext.xml配置sqlSessionFactory和数据源
sqlSessionFactory在mybatis和spring的整合包下。
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd ">
<!-- 加载配置文件 -->
<context:property-placeholder location="classpath:db.properties" />
<!-- 数据源，使用dbcp -->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<property name="maxActive" value="10" />
<property name="maxIdle" value="5" />
</bean>
<!-- sqlSessinFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 加载mybatis的配置文件 -->
<property name="configLocation" value="mybatis/SqlMapConfig.xml" />
<!-- 数据源 -->
<property name="dataSource" ref="dataSource" />
</bean>
</beans>原始dao开发(和spring整合后)
- User.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">
<!-- namespace 命名空间，作用就是对sql进行分类化管理,理解为sql隔离 注意：使用mapper代理方法开发，namespace有特殊重要的作用 -->
<mapper namespace="test">
<!-- 在映射文件中配置很多sql语句 -->
<!--需求:通过id查询用户表的记录 -->
<!-- 通过select执行数据库查询 id:标识映射文件中的sql，称为statement的id 将sql语句封装到mappedStatement对象中，所以将id称为statement的id parameterType:指定输入参数的类型 #{}标示一个占位符, #{value}其中value表示接收输入参数的名称，如果输入参数是简单类型，那么#{}中的值可以任意。 resultType：指定sql输出结果的映射的java对象类型，select指定resultType表示将单条记录映射成java对象 -->
<select id="findUserById" parameterType="int" resultType="com.iot.ssm.po.User">
SELECT * FROM user WHERE id=#{value}
</select>
</mapper>在SqlMapconfig.xml中加载User.xml
<!-- 加载映射文件-->
<mappers>
<mapper resource="sqlmap/User.xml"/>
</mappers> - dao(实现类继承
SqlSessionDaoSupport)
public interface UserDao {
//根据id查询用户信息
public User findUserById(int id) throws Exception;
}dao接口实现类需要注入SqlSessoinFactory，通过spring进行注入。这里spring声明配置方式，配置dao的bean：
让UserDaoImpl实现类继承SqlSessionDaoSupport
public class UserDaoImpl extends SqlSessionDaoSupport implements UserDao{
@Override
public User findUserById(int id) throws Exception {
//继承SqlSessionDaoSupport，通过this.getSqlSession()得到sqlSessoin
SqlSession sqlSession = this.getSqlSession();
User user = sqlSession.selectOne("test.findUserById",id);
return user;
}
}- 配置dao
在applicationContext.xml中配置dao
<!-- 原始dao接口 -->
<bean id="userDao" class="com.iot.ssm.dao.UserDaoImpl">
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>- 测试程序
public class UserDaoImplTest {
private ApplicationContext applicationContext;
//在setUp这个方法得到spring容器
@Before
public void setUp() throws Exception {
applicationContext = new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
}
@Test
public void testFindUserById() throws Exception {
// 创建UserDao的对象
UserDao userDao = (UserDao)applicationContext.getBean("userDao");
// 调用UserDao的方法
User user = userDao.findUserById(1);
System.out.println(user);
}
}mapper代理开发
- mapper.java
public interface UserMapper {
//根据id查询用户信息
User findUserById(int id) throws Exception;
}- mapper.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">
<!-- namespace 命名空间，作用就是对sql进行分类化管理,理解为sql隔离 注意：使用mapper代理方法开发，namespace有特殊重要的作用 -->
<mapper namespace="com.iot.ssm.mapper.UserMapper">
<!-- 在映射文件中配置很多sql语句 -->
<select id="findUserById" parameterType="int" resultType="user">
SELECT * FROM user WHERE id=#{value}
</select>
</mapper>- 通过
MapperFactoryBean创建代理对象
<!-- mapper配置 MapperFactoryBean：根据mapper接口生成代理对象 -->
<bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
//mapperInterface指定mapper接口
<property name="mapperInterface" value="com.iot.ssm.mapper.UserMapper"/>
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>此方法问题：需要针对每个mapper进行配置，麻烦。
- 通过
MapperScannerConfigurer进行mapper扫描（建议使用）
<!-- mapper批量扫描，从mapper包中扫描出mapper接口，自动创建代理对象并且在spring容器中注册 遵循规范：将mapper.java和mapper.xml映射文件名称保持一致，且在一个目录 中 自动扫描出来的mapper的bean的id为mapper类名（首字母小写） -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<!-- 指定扫描的包名 如果扫描多个包，每个包中间使用半角逗号分隔 -->
<property name="basePackage" value="com.iot.ssm.mapper"/>
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
</bean>- 测试代码
package com.iot.mybatis.mapper;
import com.iot.ssm.mapper.UserMapper;
import com.iot.ssm.po.User;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserMapperTest {
private ApplicationContext applicationContext;
//在setUp这个方法得到spring容器
@Before
public void setUp() throws Exception {
applicationContext = new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
}
@Test
public void testFindUserById() throws Exception {
UserMapper userMapper = (UserMapper)applicationContext.getBean("userMapper");
//调用userMapper的方法
User user = userMapper.findUserById(1);
System.out.println(user);
}
}遇到的问题
org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [D:\intellij\workspace\spring-mybatis\out\production\spring-mybatis\com\iot\ssm\mapper\UserMapper.class]; nested exception is java.lang.IllegalArgumentException
at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:281)
at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:242)
at org.mybatis.spring.mapper.ClassPathMapperScanner.doScan(ClassPathMapperScanner.java:155)
at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.scan(ClassPathBeanDefinitionScanner.java:220)
at org.mybatis.spring.mapper.MapperScannerConfigurer.postProcessBeanDefinitionRegistry(MapperScannerConfigurer.java:315)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
at com.iot.mybatis.mapper.UserMapperTest.setUp(UserMapperTest.java:17)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:69)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:48)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:292)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.lang.IllegalArgumentException
at org.springframework.asm.ClassReader.<init>(Unknown Source)
at org.springframework.asm.ClassReader.<init>(Unknown Source)
at org.springframework.asm.ClassReader.<init>(Unknown Source)
at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:52)
at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80)
at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101)
at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:257)
... 35 more- 搜到的答案
- BeanDefinitionStoreException Failed to read candidate component class
- Failed to read candidate component错误
总结起来就是java 8 和spring 3 不能一起用，我在IDEA的project settings里把project language level换成7就好了。具体原因还不清楚
作者@brianway更多文章：个人网站 | CSDN | oschina