MyBatis与Spring整合

整合背景

稍微大一点的项目都会使用SSM或者SSH框架，但是如果项目不是那么的大，用MyBatis和Spring就足够了，MyBatis的优势就是sql灵活，可以适应多变的需求；使用spring可以降低各模块之间的耦合度，方便系统的升级与维护。

整合思路

需要spring通过单例的方式管理SqlSessionFactory

spring和mybatis整合生成代理对象，使用SqlSessionFactory创建SqlSession(自动完成)

持久层mapper都需要spring进行管理

相关准备

一、创建一个Java工程

添加一个lib文件夹

二、jar准备

mybatis-3.4.4所有jar

spring4.2.1相关jar​

整合jar：mybatis-spring-1.3.1.jar​

数据库驱动：mysql-connector-java-5.1.7-bin.jar​

数据连接池：数据连接池（c3p0）​

mchange-commons-java-0.2.3.4.jar：C3P0辅助包​

EHcache缓存（如果有需要）mybatis-ehcache-1.0.3和ehcache-core-2.6.11.jar

相关jar文件导入lib文件后Build-path一下

mybatis全局配置文件

在工程中创建一个资源文件夹

在config资源夹中创建mybatis包，包中创建mybatis全局配置文件SqlMapConfig.xml

把连接数据库的配置抽取到db.properties，以便后期维护

为了方便调试，建立日志文件log4j.properties

在config资源夹中创建spring包，包中创建spring全局配置文件applicationContext.xml

db.properties内容

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/MyBatis?useUnicode=true&characterEncoding=UTF8
jdbc.username=root
jdbc.password=123456

log4j.properties内容

#Global logging configuration

log4j.rootLogger=DEBUG, stdout
# MyBatis logging configuration...
log4j.logger.org.mybatis.example.BlogMapper=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

SqlMapConfig.xml暂时简单配置一下

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

</configuration>

applicationContext.xml也暂时简单配置一下

<?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: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.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
</beans>

创建几个文件包

最后项目结构差不多就是这样

在applicationContext.xml中配置数据源和SqlSessionFactory

<!-- 加载数据库配置信息 -->
     <context:property-placeholder location="classpath:db.properties"/>
 <!-- 数据源配置 -->
  <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
    <property name= "driverClass" value="${jdbc.driver}"></property>
    <property name="jdbcUrl" value="${jdbc.url}"></property>
    <property name="user" value="${jdbc.username}"></property>
    <property name="password" value="${jdbc.password}"></property>
        </bean>


  <!-- SqlSessionFactory配置 
       class：属性在mybatis-spring-1.3.1的第一个包中
  -->
  <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
   <!-- 加载mybatis的配置文件 -->
   <property name="configLocation" value="mybatis/SqlMapConfig.xml"></property>
    <!-- 数据源 -->
    <property name="dataSourcev" ref="dataSource"></property>
</bean>

建一个pojo类（User.java）

package com.hl.ld.pojo;

import java.util.Date;

public class User {

    private int id;
    private String username;
    private char sex;
    private Date birthday;
    private String address;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public char getSex() {
        return sex;
    }
    public void setSex(char sex) {
        this.sex = sex;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", sex=" + sex
                + ", birthday=" + birthday + ", address=" + address + "]";
    }

}

因为打算用mapper接口的方式开发，所以要采用mapper规范

具体请参考：Mybatis Mapper代理开发规范

创建UserMapper.xml，写几个statement

<!DOCTYPE mapper
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.hl.ld.mapper.UserMapper">

    <select id="findUserById" parameterType="int" resultType="user">
        select * FROM user WHERE id = #{id}
    </select>

    <select id="findUserByName" parameterType="String" resultType="user">
        select * FROM user WHERE address LIKE '%${value}%'
    </select>

    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id = #{value}
    </delete>

</mapper>

根据mapper代理开发规范创建UserMapper.java接口

package com.hl.ld.mapper;


import java.util.List;

import com.hl.ld.pojo.User;


public interface UserMapper {

    //根据id查询用户信息
    public User findUserById(int id) throws Exception;
    //根据id删除用户
    public void deleteUser(int id);
    //根据用户姓名模糊查找
    public List<User> findUserByName(String name);
}

在SqlMapConfig.xml中定义pojo类的别名

<!-- 别名 -->
<typeAliases>

<!-- 批量定义别名
指定包名，MyBatis会自动扫描包内类，自动定义别名，别名就是类名，首字母不区分大小写
 -->
<package name="com.hl.ld.pojo"/>
</typeAliases>

在SqlMapConfig.xml中引入映射文件UserMapper.xml

<!-- 加载映射文件 -->
  <mappers>
    <package name="com.hl.ld.mapper.UserMapper"/>
  </mappers>

applicationContext.xml中配置mapper接口

<!-- mapper的配置,通过MapperFactoryBean生成代理对象
     name:根据指定接口生成代理对象
 -->
<bean id="userMaper" class="org.mybatis.spring.mapper.MapperFactoryBean">
       <property name="mapperInterface" value="com.hl.ld.mapper.UserMapper"/>
       <!-- sqlSessionFactory -->
       <property name="sqlSessionFactory" res="sqlSessionFactory"/>

</bean>

测试

package com.hl.ld.test;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.hl.ld.mapper.UserMapper;
import com.hl.ld.pojo.User;


public class SpringMybatisTest {
    private ApplicationContext applicationContext;

    @Before
    public void before(){
        String configLocation = "classpath:spring/applicationContext.xml";
        //获取spring容器
        applicationContext = new ClassPathXmlApplicationContext(configLocation);
    }
    @Test
    public void testFindUserById() throws Exception{
        UserMapper userMaper = (UserMapper) applicationContext.getBean("userMaper");
        User user = userMaper.findUserById(3);
        System.out.println(user);
    }
}

结果：

DEBUG [main] - ==>  Preparing: select * FROM user WHERE id = ? 
DEBUG [main] - ==> Parameters: 3(Integer)
DEBUG [main] - <==      Total: 1
DEBUG [main] - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2556db07]
DEBUG [main] - Returning JDBC Connection to DataSource
DEBUG [main] - com.mchange.v2.async.ThreadPoolAsynchronousRunner@ab519aa: Adding task to queue -- com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@4867b7f4
DEBUG [main] - trace com.mchange.v2.resourcepool.BasicResourcePool@6d05629f [managed: 3, unused: 2, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@4a8f5018)
DEBUG [C3P0PooledConnectionPoolManager[identityToken->1hge0ys9ojz0qmodgyzri|85132f5]-HelperThread-#0] - com.mchange.v2.c3p0.impl.NewProxyConnection@38cf9a71: close() called more than once.
User [id=3, username=项羽, sex=1, birthday=Wed Apr 05 00:00:00 CST 2017, address=秦时明月之万里长城]

花了点时间，还是实现了

源码在此