MyBatis第一个程序

创建一个maven项目，并且在pom.xml导入myBatis和jdbc的jar包

<dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
</dependencies>

在resource配置mybatis-config.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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="a1814995041"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/flsh/dao/userMapper.xml"/>
    </mappers>
</configuration>

创建mybatis的工具类mybatisUtil.classpackage com.mybatis.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 mybatisUtil {
    private static SqlSessionFactory sqlSessionFactory;

    static{
        //第一步创建sqlSessionFactory对象
        try {
            String resource = "mybatis-config.xml";
　　　　　//获取对应的配置文件
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSession getSqlSession(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession;
    }
}

创建数据实体的文件夹pojo，再在pojo中新建User实体类

package com.mybatis.pojo;

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

    public User() {
    }

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

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

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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;
    }
}

在java文件夹中创建dao的文件加下UserMapper.class的接口

package com.mybatis.mapper;

import com.mybatis.pojo.User;

import java.util.List;

public interface UserMapper {
    List<User> selectUser();
    void addUser(User user);
    void updateUser(User user);
    void deleteUser(int id);

}

配对的UserMapper接口，在同一目录中创建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">
<!--    namespace:接口名-->
<mapper namespace="com.mybatis.mapper.UserMapper">
<!--    id:方法名  resultType:返回类型-->
    <select id="selectUser" resultType="com.mybatis.pojo.User">
        select * from user
    </select>
    <update id="updateUser" parameterType="com.mybatis.pojo.User">
        update user set name=#{name},pwd=#{pwd} where id=#{id}
    </update>
    <delete id="deleteUser" parameterType="int">
        delete from user where id=#{id}
    </delete>
    <insert id="addUser" parameterType="com.mybatis.pojo.User">
        insert into user (id,name,pwd) values (#{id},#{name},#{pwd})
    </insert>
</mapper>

在Test.java的测试文件夹，创建测试类UserTest.class

package com.mybatis.mapper;

import com.mybatis.pojo.User;
import com.mybatis.utils.mybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserTest {
    @Test
    public void selectUser(){
//调用mybatis的工具类
        SqlSession sqlSession = mybatisUtil.getSqlSession();
//mapper：映射器　　通过sqlSession.getMapper获取UserMapper接口中的方法
        UserMapper mapper =  sqlSession.getMapper(UserMapper.class);
        List<User> users = mapper.selectUser();
        for(User user : users){
            System.out.println(user);
        }
        sqlSession.close();
    }
    @Test
    public void addUser(){
        SqlSession sqlSession = mybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.addUser(new User(4,"四郎","123456"));

        //提交事务
        sqlSession.commit();
        //关闭sql
        sqlSession.close();
    }
    @Test
    public void updateUser(){
        SqlSession sqlSession = mybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.updateUser(new User(4,"五郎","123456"));

        //提交事务
        sqlSession.commit();
        //关闭sql
        sqlSession.close();
    }
    @Test
    public void deleteUser(){
        SqlSession sqlSession = mybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.deleteUser(4);

        //提交事务
        sqlSession.commit();
        //关闭sql
        sqlSession.close();
    }

}