mabatis——namespace绑定接口

Mapper中的namespace用于绑定Dao接口的，即面向接口编程。

它的好处在于当使用了namespace之后就可以不用写接口实现类，业务逻辑会直接通过这个绑定寻找到相对应的SQL语句进行对应的数据处理

mybatis-config

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "mybatis-3-config.dtd">
<configuration>
    <settings>
        <!-- 指定使用LOG4J输出日志 -->
        <setting name="logImpl" value="LOG4J"/>
    </settings>
    <typeAliases>
        <!-- 配置包的别名，通常在使用类时需要使用类的全限定名称，使用该配置后只要直接使用类名即可 -->
        <package name="com.etc.model"/>
    </typeAliases>
    <!-- 数据库环境 -->
    <environments default="development">
        <environment id="development">
            <!-- 采用JDBC管理器方式 -->
            <transactionManager type="JDBC"/>
            <!-- POOLED采用mybabtis内部连接池方式 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="1234"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="\userMapping.xml"/>
    </mappers>
</configuration>

 log4j.properties

#全局配置
log4j.rootLogger=ERROR,stdout

#MyBatis日志配置
log4j.logger.com.etc.mapper=TRACE

#控制台输出配置
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

userMapping中namepace绑定UserDao接口

<?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.etc.dao.UserDao">
   
    <select id="queryAll" resultType="User">
        select * from user
    </select>

</mapper>

User

package com.etc.model;

public class User {
    private int id;
    private String name;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

UserDao

package com.etc.dao;

import com.etc.model.User;

import java.util.List;

public interface UserDao {

    List<User> queryAll();

}

BaseMapper

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 org.junit.Before;

import java.io.IOException;
import java.io.InputStream;

public class BaseMapper {

    private  SqlSessionFactory sqlSessionFactory;

    @Before
    public  void init() throws IOException {
        InputStream inputStream = null;
        try {
            String resource = "mybatis-config.xml";
            inputStream = Resources.getResourceAsStream(resource);
            this.sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (inputStream!=null){
                inputStream.close();
            }
        }
    }

    public SqlSession getSqlSession(){
        return this.sqlSessionFactory.openSession();
    }
}

UserTest

import com.etc.dao.UserDao;
import com.etc.model.User;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserTest extends BaseMapper {
 
    @Test
    public void queryAll(){
        try (SqlSession sqlSession =  this.getSqlSession()){
            UserDao dao = sqlSession.getMapper(UserDao.class);
            List<User> list = dao.queryAll();
            System.out.println(list);
        }
    }
}