Spring整合Mybatis—Mapper代理开发

缺乏、安全感 2022-05-17 02:36 368阅读 0赞

#### 整合思路 ####

*  SqlSessionFactory对象放入spring容器中作为单例实例存在
 *  mapper代理开发中，直接从spring容器中获得mapper的代理对象。
 *  数据库的连接方式，数据库连接池，事物管理都交给spring容器来管理
 *  传统的dao开发，从spring容器中获得sqlsession对象

#### 整合步骤 ####

*  导包  
    spring包(包括了SpringMvc)  
    ![这里写图片描述][70]  
    mybatis包  
    ![这里写图片描述][70 1]  
    数据库驱动和连接池包  
    ![这里写图片描述][70 2]  
    mybatis核心和spring整合包  
    ![这里写图片描述][70 3]
    
     *  编写SqlMapConfig.xml配置文件

<?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>
        
        <typeAliases>
            
            <package name="cn.itcast.mybatis.pojo" />
        </typeAliases>
        
        <mappers>
            <package name="cn.itcast.mybatis.mapper"/>
        </mappers>
    </configuration>

*  数据库连接配置文件

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8
    jdbc.username=root
    jdbc.password=root

*  log4j文件

# Global logging configuration
    log4j.rootLogger=DEBUG, stdout
    # 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

*  applicationContext.xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd">
    
       
       <context:property-placeholder location="classpath:db.properties" />
    
        
        <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>
    
        
        <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            
            <property name="dataSource" ref="dataSource" />
            
            <property name="configLocation" value="classpath:SqlMapConfig.xml" />
        </bean>
    </beans>

*  编写UserMapper.xml配置文件

<?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="cn.itcast.mybatis.mapper.UserMapper">
        
        <select id="queryUserById" parameterType="int" resultType="user">
            select * from user where id = #{id}
        </select>
    
        
        <select id="queryUserByUsername" parameterType="string" resultType="user">
            select * from user where username like '%${value}%'
        </select>
    
        
        <insert id="saveUser" parameterType="user">
            <selectKey keyProperty="id" keyColumn="id" order="AFTER" resultType="int">
                select last_insert_id()
            </selectKey>
            insert into user
            (username,birthday,sex,address) values
            (#{username},#{birthday},#{sex},#{address})
        </insert>
    </mapper>

*  编写UserMapper接口，与UserMapper.xml文件放在同一个目录下

public interface UserMapper { 
        /** * 根据用户id查询 * * @param id * @return */
        User queryUserById(int id);
    
        /** * 根据用户名模糊查询用户 * * @param username * @return */
        List<User> queryUserByUsername(String username);
    
        /** * 添加用户 * * @param user */
        void saveUser(User user);
    }

**在spring配置文件中配置mapper代理**  
自动手动获得代理对象需要通过sqlSession来获得代理对象  
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);  
交给spring容器管理后，就需要先给一个sqlSession对象，获得sqlSession对象，需要注入sqlSessionFactory。获得代理对象需要给一个Mapper对象的接口，所以将接口注入到MapperFactoryBean中

<bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
        
        <property name="mapperInterface" value="cn.itcast.mybatis.mapper.UserMapper" />
    </bean>

*  测试

package cn.itcast.mybatis.junit;
    
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import cn.itcast.mybatis.mapper.UserMapper;
    import cn.itcast.mybatis.pojo.User;
    
    public class JunitTest {
    
    
        @Test
        public void testMapper() throws Exception {
            ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
            //通过接口获得代理对象
            UserMapper mapper = ac.getBean(UserMapper.class);
            //通过id获得代理对象        
            //UserMapper mapper = (UserMapper) ac.getBean("userMapper");
            User user = mapper.queryUserById(10);
            System.out.println(user);
        }
    }

**扫描开发**(推荐)

*  修改applicationContext.xml配置文件  
    这里不需要注入sqlSessionFactory对象，因为一旦配置加载了sqlSessionFactory对象，就在spring的容器中，MapperScannerConfigurer会自动扫描获取 ，所以只需要指定基本包，就会自动扫描mapper配置文件。

<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
            
            <property name="basePackage" value="com.itheima.mybatis.mapper"/>
        </bean>

*  测试

package cn.itcast.mybatis.junit;
    
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import cn.itcast.mybatis.mapper.UserMapper;
    import cn.itcast.mybatis.pojo.User;
    
    public class JunitTest {
    
    
        @Test
        public void testMapper() throws Exception {
            ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
            //通过接口获得代理对象
            UserMapper mapper = ac.getBean(UserMapper.class);
            //通过id获得代理对象，由于通过自动扫描的方式获得，没有命名id，所以就不能通过这种方式获得mapper代理对象。
            //UserMapper mapper = (UserMapper) ac.getBean("userMapper");
            User user = mapper.queryUserById(10);
            System.out.println(user);
        }
    }

[70]: /images/20220517/3906e84580074bd4b2ab2ba3e746ef45.png
[70 1]: /images/20220517/b90aa3c61a3f4a5aa7dba55802770c00.png
[70 2]: /images/20220517/f1b9519e93064b5b81f12e3f73948250.png
[70 3]: /images/20220517/3df60ebf0603412f91aab9315a57a549.png