三、注入映射器实现

作者: lifeline张 | 来源:发表于2018-08-31 10:11 被阅读0次

一、本课目标

能够以配置的方式生成映射器的实现：

掌握MapperFactoryBean的配置
掌握MapperScannerConfigurer的配置

二、注入映射器

2.1为什么需要注入映射器的实现

手动编写映射器实现存在的问题

SqlSession.selectList()等方法需要采用字符串来指定映射项。字符串出错的话则只能在运行的时候才能发现。
SqlSession.getMapper()方法需要在每次调用时都实现一次映射器接口。

那能否在IOC容器中始终存在一个映射器接口的实现呢？

2.2注入映射器的实现

采用数据映射（MapperFactoryBean）的方式完成对数据库操作。

根据Mapper接口湖区Mapper对象，它封装了原有的SqlSession.getMapper()功能的实现。

image.png

配置文件：

<?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:p="http://www.springframework.org/schema/p"
    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/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">
    
    <!-- 配置数据源 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://127.0.0.1:3306/smbms?
                        useUnicode=true&amp;characterEncoding=utf-8"></property>
        <property name="username" value="root"></property>
        <property name="password" value="41312019"></property>
    </bean>
    <!-- 配置SqlSessionFactoryBean -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="configLocation" value="classpath:mybatis-config.xml"></property>
        <property name="mapperLocations">
            <list>
                <value>classpath:cn/smbms/dao/**/*.xml</value>
            </list>
        </property>
    </bean>

    <!-- 配置SqlSessionTemplate -->
    <!-- <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactory"></constructor-arg>
    </bean> -->
    
    <bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="mapperInterface" value="cn.smbms.dao.user.UserMapper"></property>
        <property name="sqlSessionFactory" ref="sqlSessionFactory"></property>
    </bean>
    
    <bean id="userService" class="cn.smbms.service.user.UserServiceImpl">
        <property name="userMapper" ref="userMapper"></property>
    </bean>
</beans>

当配置文件这么写的时候，就可以把UserMapperImpl文件直接删除掉了，不需要使用这个文件的实现类去获取sqlSession以及调用sqlSession的getMapper方法去获取数据了。

2.3注入映射器的实现2

如果映射器很多的话，相应的配置项也会很多，如何简化配置工作量？
MapperScannerConfigurer

自动扫描指定包下面的Mapper接口，并将它们直接注册为MapperFactoryBean。
这个类注册的配置文件中是没有id的，他会把相应的mapper类的首字母小写作为相应的mapper的bean的名字。

image.png

此时配置文件如下：

<?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:p="http://www.springframework.org/schema/p"
    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/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">
    
    <!-- 配置数据源 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://127.0.0.1:3306/smbms?
                        useUnicode=true&amp;characterEncoding=utf-8"></property>
        <property name="username" value="root"></property>
        <property name="password" value="41312019"></property>
    </bean>
    <!-- 配置SqlSessionFactoryBean -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="configLocation" value="classpath:mybatis-config.xml"></property>
        <property name="mapperLocations">
            <list>
                <value>classpath:cn/smbms/dao/**/*.xml</value>
            </list>
        </property>
    </bean>

    <!-- 配置SqlSessionTemplate -->
    <!-- <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactory"></constructor-arg>
    </bean> -->
    
    <!-- <bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="mapperInterface" value="cn.smbms.dao.user.UserMapper"></property>
        <property name="sqlSessionFactory" ref="sqlSessionFactory"></property>
    </bean> -->
    
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="cn.smbms.dao"></property>
    </bean>
    <bean id="userService" class="cn.smbms.service.user.UserServiceImpl">
        <property name="userMapper" ref="userMapper"></property>
    </bean>
</beans>

运行结果正常。

image.png

此时配置文件如下：

<?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:p="http://www.springframework.org/schema/p"
    xmlns:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-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
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.2.xsd">
    
    <!-- 配置数据源 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://127.0.0.1:3306/smbms?
                        useUnicode=true&amp;characterEncoding=utf-8"></property>
        <property name="username" value="root"></property>
        <property name="password" value="41312019"></property>
    </bean>
    <!-- 配置SqlSessionFactoryBean -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="configLocation" value="classpath:mybatis-config.xml"></property>
        <property name="mapperLocations">
            <list>
                <value>classpath:cn/smbms/dao/**/*.xml</value>
            </list>
        </property>
    </bean>

    <!-- 配置SqlSessionTemplate -->
    <!-- <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactory"></constructor-arg>
    </bean> -->
    
    <!-- <bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="mapperInterface" value="cn.smbms.dao.user.UserMapper"></property>
        <property name="sqlSessionFactory" ref="sqlSessionFactory"></property>
    </bean> -->
    
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="cn.smbms.dao"></property>
    </bean>
    <!-- Service -->
    <context:component-scan base-package="cn.smbms.service.user"></context:component-scan>
    <!-- <bean id="userService" class="cn.smbms.service.user.UserServiceImpl">
        <property name="userMapper" ref="userMapper"></property>
    </bean> -->
</beans>

增加一个service包，里面放service层：

package cn.smbms.service.user;

import java.util.List;
import cn.smbms.pojo.User;

public interface UserService {
    public List<User> findUsersWithConditions(User user);
}

通过注解给service实现类入参：

package cn.smbms.service.user;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;

import cn.smbms.dao.user.UserMapper;
import cn.smbms.pojo.User;

@Service("userService")
public class UserServiceImpl implements UserService {
    @Autowired
    @Qualifier("userMapper")
    private UserMapper userMapper;

    @Override
    public List<User> findUsersWithConditions(User user) {
        try {
            return userMapper.getUserList(user);
        } catch (RuntimeException e) {
            e.printStackTrace();
            throw e;
        }
    }

    public UserMapper getUserMapper() {
        return userMapper;
    }

    public void setUserMapper(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

}

测试代码：

  @Test void testUserService() {
         ApplicationContext ctx = new ClassPathXmlApplicationContext(
                 "applicationContext.xml");
         UserService userService = (UserService) ctx.getBean("userService");
         List<User> userList = new ArrayList<User>();
         User userCondition = new User();
         userCondition.setUserName("赵");
         userCondition.setUserRole(3);
         userList = userService.findUsersWithConditions(userCondition);

         for (User userResult : userList) {
             logger.debug("testGetUserList userCode: "
                     + userResult.getUserCode() + " and userName: "
                     + userResult.getUserName() + " and userRole: "
                     + userResult.getUserRole() + " and userRoleName: "
                     + userResult.getUserRoleName() + " and address: "
                     + userResult.getAddress());
         }
    }

运行结果：

image.png

三、注入映射器实现

一、本课目标

二、注入映射器

2.1为什么需要注入映射器的实现

2.2注入映射器的实现

2.3注入映射器的实现2

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