Mybatis 整合 Spring【mapper动态代理】

布满荆棘的人生 2021-12-11 14:57 298阅读 0赞

## 1 创建工程并导入jar包【spring的jar包、Mybatis的jar包、Spring+mybatis的整合包、Mysql的数据库驱动jar包、数据库连接池的jar包dbcp】 ##

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## 2  编写mybatis和spring的配置文件 ##

SqlMapConfig.xml

<?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="com.entity" />
    	</typeAliases>
    
    	
        
    	
    	<mappers>
    		<package name="com.mapper"/>
    	</mappers>
    </configuration>

applicationContext.xml

<?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">
    
    	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
    		destroy-method="close">
    		<property name="driverClassName" value="com.mysql.jdbc.Driver" />
    		<property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />
    		<property name="username" value="root" />
    		<property name="password" value="root" />
    		<property name="maxActive" value="10" />
    		<property name="maxIdle" value="5" />
    	</bean>
    
    
    	
    	<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    		
    		<property name="configLocation" value="classpath:SqlMapConfig.xml" />
    		
    		<property name="dataSource" ref="dataSource" />
    	</bean>
    
    
    
    	
    	
    
    	
    	<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    		
    		
    		<property name="basePackage" value="com.mapper"/>
    	</bean>
    
    	
    </beans>

##  3 编写实体类 ##

package com.entity;
    
    import java.util.Date;
    import java.util.List;
    
    public class User {
    	private Integer id;
    	private String username;
    	private String sex;
    	private Date birthday;
    	private String address;
           ......get/set.......
    
    }

4 编写mapper文件

Mapper接口开发需要遵循以下规范：

**Mapper.xml文件中的namespace与mapper接口的类路径相同。  
Mapper接口方法名和Mapper.xml中定义的每个statement的id相同  
Mapper接口方法的输入参数类型和mapper.xml中定义的每个sql 的parameterType的类型相同  
Mapper接口方法的输出参数类型和mapper.xml中定义的每个sql的resultType的类型相同**

package com.mapper;
    
    import com.entity.User;
    
    public interface UserMapper {
    	public User findById(Integer id);
    }

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.mapper.UserMapper">
    <select id="findById" parameterType="Integer" resultType="User">
    	select * from user where id = #{id}
    </select>
    
    </mapper>

5 测试类

package com.test;
    
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import com.entity.User;
    import com.mapper.UserMapper;
    
    public class MapperTest {
    	@Test
    	public void testMapper() {
    		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
    	
    		//UserMapper userMapper = (UserMapper) applicationContext.getBean("userMapper");
    		//这里我们并没有直接使用在spring里面的id，而是实现类【UserMapper.class】，因此mapper的动态代理和包扫描都可以用这样实现
    		UserMapper userMapper = applicationContext.getBean(UserMapper.class);
    		User user = userMapper.findById(1);
    		System.out.println(user);
    	}
    }

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