第一个MyBatis程序

1、建立数据库

CREATE DATABASE `mybatis`;
use `mybatis`;
CREATE TABLE `user`(
    `id` INT(20) NOT NULL PRIMARY KEY,
        `name` VARCHAR(30) DEFAULT NULL,
    `pwd` VARCHAR(30) DEFAULT NULL
)ENGINE=INNODB DEFAULT CHARSET=utf8;

INSERT INTO `user`(`id`,`name`,`pwd`) VALUES
(1,'王五','123456'),
(2,'张三','123456'),
(3,'李四','123456')

2、新建一个maven项目

2.1删除src目录，使其成为父工程，pom.xml：

<?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>4.0.0modelVersion>

    <groupId>org.examplegroupId>
    <artifactId>Mybatis-studyartifactId>
    <version>1.0-SNAPSHOTversion>


    <dependencies>
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>5.1.47version>
        dependency>
        <dependency>
            <groupId>org.mybatisgroupId>
            <artifactId>mybatisartifactId>
            <version>3.5.6version>
        dependency>
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
            <scope>testscope>
        dependency>
    dependencies>


project>

2.2新建一个模块，即子工程

编写mybaties核心配置文件

<?xml version="1.0" encoding="UTF-8" ?>
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

    
        
            
            
                
                
                
                
            
        
    
    
        
    

此处的需要定位mapper.xml的位置！！

编写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.lwx.dao.UserDao">
    <select id="getUserList" resultType="com.lwx.pojo.User">
    select * from mybatis.user
  select>
mapper>

pojo层，user代码（实体类）：

package com.lwx.pojo;

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

    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    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 getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

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

utils工具类，MybatisUtils：

package com.lwx.utils;

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;

public class MybatisUtils {
public static SqlSessionFactory sqlSessionFactory;
    static {

        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public  static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();

    }
}

dao层：

UserDao：

package com.lwx.dao;

import com.lwx.pojo.User;

import java.util.List;

public interface UserDao {
   List getUserList();
}

测试类：

UserDaoTest

package com.lwx.dao;

import com.lwx.pojo.User;
import com.lwx.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void  test() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        //UserDao mapper = sqlSession.getMapper(UserDao.class);
        List userList = userDao.getUserList();
        for(User user :userList){
            System.out.println(user);
        }
        sqlSession.close();
    }
}

运行程序，成功查询了数据库中的信息