Mybatis

Mybatis基础
添加mybatis的依赖，目前版本是3.4.6，除此之外还有junit和mysql的驱动依赖分别引入进来

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">
4.0.0

com.qfedu
Days21Mybatis
1.0-SNAPSHOT


    
        mysql
        mysql-connector-java
        5.1.44
    
    
        junit
        junit
        4.12
    
    
        org.mybatis
        mybatis
        3.4.6
    

在resources目录下新增一个mybatis的配置文件，mybatis.xml

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">

在com.qfedu.pojo的包下创建User.java文件

package com.qfedu.pojo;

public class User {

private int uid;
private String username;
private String password;
private int age;
private String addr;

@Override
public String toString() {
    return "User{" +
            "uid=" + uid +
            ", username='" + username + '\'' +
            ", password='" + password + '\'' +
            ", age=" + age +
            ", addr='" + addr + '\'' +
            '}';
}

public int getUid() {
    return uid;
}

public void setUid(int uid) {
    this.uid = uid;
}

public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public String getPassword() {
    return password;
}

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

public int getAge() {
    return age;
}

public void setAge(int age) {
    this.age = age;
}

public String getAddr() {
    return addr;
}

public void setAddr(String addr) {
    this.addr = addr;
}

}

在com/qfedu/pojo的目录下创建UserMapper.xml文件

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">


select * from user

TestUser.java

package com.qfedu.test;

import com.qfedu.pojo.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 org.junit.Test;

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

public class TestUser {

@Test
public void testGetAllUsers(){

    /**
     *  1.  使用mybatis的配置文件以及SqlSessionFactoryBuilder建造者模式创建SqlSessionFactory对象
     *  2.  使用SqlSessionFactory对象的openSession（）方法来得到一个SqlSession对象，用该对象即可完成对象的所有的crud操作
     *  3.  使用SqlSession对象来完成crud操作
     *  4.  关闭资源
     *
     */
    try {
        SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));

        SqlSession session = sf.openSession();

        /**
         * session的crud方法（"namespace.id"）;整个项目中的namespace.id必须唯一
         */
        List users = session.selectList("com.qfedu.pojo.UserMapper.selectUser");

        for (User u : users) {
            System.out.println(u);
        }

        if(session != null){
            session.close();
            session = null;
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}

执行结果

User{uid=1, username='sunwukong', password='111111', age=500, addr='huaguoshan'}
User{uid=2, username='zhubajie', password='222222', age=2000, addr='gaolaozhuang'}
User{uid=3, username='shaheshang', password='333333', age=500, addr='liushahe'}
User{uid=4, username='tangtang', password='444444', age=20, addr='datangwangchao'}
User{uid=5, username='baikongma', password='555555', age=100, addr='longgong'}
User{uid=6, username='1111', password='', age=20, addr=''}
User{uid=7, username='baigujing', password='888888', age=800, addr='baigudong'}
User{uid=8, username='nverguowang', password='888888', age=18, addr='nuerguo'}
User{uid=9, username='heixiongjing', password='888888', age=1800, addr='heifengdong'}
User{uid=10, username='tieshan', password='888888', age=900, addr='huoyanshan'}
User{uid=11, username='lishushu', password='888888', age=18, addr='beijing'}
User{uid=12, username='change', password='888888', age=1000, addr='guanghangong'}