mybatis实现简单的增删改查

项目结构

添加maven依赖

创建好springboot项目后在pom.xml中添加

// An highlighted block
<dependency>
   <groupId>org.mybatis</groupId>
   <artifactId>mybatis</artifactId>
   <version>3.4.5</version>
</dependency>
<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>5.1.43</version>
</dependency>

配置mybatis-config.xml

下面展示一些 内联代码片。

// An highlighted block
<?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>
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/><!--配置数据库驱动-->
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/db?useUnicode=true&amp;characterEncoding=utf-8&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="admin"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="mapper/UserMapper.xml"/><!--注意-->
    </mappers>
</configuration>

创建UserMapper.xml

// An highlighted block
<?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="Dao.UserMapper">
    <select id="selectUser" resultType="Domain.User">
     select * from user
    </select>

    <select id="searchId" resultType="Domain.User">
        select * from user where id=#{User_id}
    </select>


    <insert id="add" parameterType="Domain.User" useGeneratedKeys="true" keyProperty="id" keyColumn="id">
        INSERT INTO `user` ( `Id`, `pwd`, `name`)
         VALUES
          (#{id},#{pwd},#{name});
</insert>
<update id="update" parameterType="Domain.User">
    update user
    set
    pwd=#{pwd},
    name=#{name}
    where Id=#{id}
</update>

<delete id="delete" parameterType="Domain.User">
    delete  from user where Id=#{id}
</delete>
</mapper>

创建dao层并写UserMapper

// An highlighted block
package Dao;

import Domain.User;

import java.util.List;

public interface UserMapper {
      //查询所有用户
      List<User> selectUser();
      //按id查询
      User searchId(int id);
      //添加用户
     void add(User user);
     //更改信息
     void update(User user);
     //删除用户
     void delete(User user);
}

创建实体类Domain层并写User

// An highlighted block
package Domain;

public class User {
private  int id;

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

在主程序中测试增删改查

// An highlighted block
package com.zhang.firstproject;
import Dao.UserMapper;
import 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 org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

@SpringBootApplication
public class FirstprojectApplication {

   public FirstprojectApplication() throws IOException {
   }

   public static void main(String[] args) {
      SpringApplication.run(FirstprojectApplication.class, args);
   }

   String resouce = "config/mybatis-config.xml";
   InputStream inputStream = Resources.getResourceAsStream(resouce);
   SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
   SqlSession sqlSession = sqlSessionFactory.openSession();
   {
   UserMapper usermapper = sqlSession.getMapper(Dao.UserMapper.class);
   User user = new User();
   user.setPwd("1234");
   user.setName("张五");
   usermapper.add(user);
   sqlSession.commit();//防止插入运行成功,但没有插入数据库中
    List<User> alluser = usermapper.selectUser();
    System.out.println(alluser.toString());
}
}

创建db数据库,建立user表

运行结果