SSM12【Mybatis：Mybatis的dao层实现】

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.haifei</groupId>
    <artifactId>SSM12_mybatis_dao</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>


    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.32</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>


    <build>
        <plugins>
            <!--jdk编译插件-->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <target>1.8</target>
                    <source>1.8</source>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>


</project>

<?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">

<!--The content of element type "configuration" must match
"(properties?,settings?,typeAliases?,typeHandlers?,objectFactory?,
objectWrapperFactory?,reflectorFactory?,plugins?,environments?,databaseIdProvider?,mappers?)".-->

<configuration>

    <!--加载外部properties文件-->
    <properties resource="jdbc.properties"></properties>

    <!--自定义别名(必须放在settings配置之后，typeHandlers配置之前，不然xml报错)-->
    <typeAliases>
        <typeAlias type="com.haifei.domain.User" alias="user" />
    </typeAliases>


    <environments default="development">  <!--environments下可以定义多个environment，default值为所指定的默认environment的id-->
        <!--配置数据源环境-->
        <environment id="development"> <!--id值自定义-->
            <transactionManager type="JDBC"></transactionManager> <!--指定事务管理器为JDBC类型-->
            <dataSource type="POOLED">  <!--指定数据源类型POOLED池-->
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>

    <!--加载映射文件-->
    <mappers>
        <mapper resource="com/haifei/mapper/UserMapper.xml"></mapper>
    </mappers>

</configuration>

 

传统开发方式

 

 

 

<?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="userMapper">

    <select id="findAll" resultType="user">
        select * from user
    </select>

</mapper>

package com.haifei.dao;

import com.haifei.domain.User;

import java.io.IOException;
import java.util.List;

public interface UserMapper {

    public List<User> findAll() throws IOException;

}

package com.haifei.dao;

import com.haifei.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class UserMapperImpl implements UserMapper{

    @Override
    public List<User> findAll() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<User> userList = sqlSession.selectList("userMapper.findAll");
        return userList;
    }

}

package com.haifei.service;

import com.haifei.dao.UserMapper;
import com.haifei.dao.UserMapperImpl;
import com.haifei.domain.User;

import java.io.IOException;
import java.util.List;

/**
 * Mybatis的Dao层实现--传统开发方式
 * Service test
 */
public class ServiceDemo {

    public static void main(String[] args) throws IOException {
        UserMapper userMapper = new UserMapperImpl(); //创建dao层对象UserMapper，当前dao层实现UserMapperImpl是手动编写的
        List<User> userList = userMapper.findAll();
        System.out.println(userList); //[User{id=1, username='zhangsan', password='123'}, User{id=2, username='lisi', password='345'}, User{id=6, username='tom', password='abc'}]
    }

}

 

代理开发方式

 

 

 

 

<?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="userMapper">
    <select id="findAll" resultType="user">
        select * from user
    </select>
</mapper>-->

<mapper namespace="com.haifei.dao.UserMapper">
    <select id="findAll" resultType="user">
        select * from user
    </select>
    <select id="findById" resultType="user" parameterType="int">
        select * from user where id=#{id}
    </select>
</mapper>

package com.haifei.dao;

import com.haifei.domain.User;

//import java.io.IOException;
import java.util.List;

public interface UserMapper {

    public List<User> findAll();
    public User findById(int id);

}

package com.haifei.service;

import com.haifei.dao.UserMapper;
import com.haifei.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

/**
 * Mybatis的Dao层实现--代理开发方式
 * Service test
 */
public class ServiceDemo2 {

    public static void main(String[] args) throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //mybatis框架自动对接口进行了内部实现，而不再需要程序员手动实现，但要遵循代理开发方式的规则
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        List<User> userList = mapper.findAll();
        System.out.println(userList); //[User{id=1, username='zhangsan', password='123'}, User{id=2, username='lisi', password='345'}, User{id=6, username='tom', password='abc'}]
        User user = mapper.findById(1);
        System.out.println(user); //User{id=1, username='zhangsan', password='123'}
    }

}