mybatis增删改查

MyBatis 是一款优秀的持久层框架，它支持定制化 SQL、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以使用简单的 XML 或注解来配置和映射原生信息，将接口和 Java 的 POJOs(Plain Ordinary Java Object,普通的 Java对象)映射成数据库中的记录。

MySQL创建数据库和数据表

CREATE DATABASE `mybatis1`;
use `mybatis1;`
CREATE TABLE `user` (
  `id` int NOT NULL,
  `name` varchar(30) DEFAULT NULL,
  `pwd` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `user` (`id`,`name`,`pwd`) VALUES
(1,`张三`,`123456`)，
(2,`大头儿子`,`963258`)，
(3,`张三王麻子`,`456789`)

新建一个普通的maven项目

pom文件存放mybatis所存放需要的jar包

<?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>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>mybatisks</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>mybatis-01</module>
    </modules>
    <!--导入依赖-->
    <dependencies>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!--mybatis-->
        <!--https://mvnrepository.com/artigact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.7</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <!--在build中配置resources，来防止我们资源导出失败的问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>
</project>

在pojo中编写实体类：

package com.bjwl.pojo;

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

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

在dao/mapper包中存放user接口类和对应的映射文件

package com.bjwl.dao;

import com.bjwl.pojo.User;

import java.util.List;

public interface UserMapper {
   //查询全部用户
   List<User> getUserList();
   //根据id查询用户
   User getUserById(int id);
   //insert插入一个用户
   int addUser(User user);
   //修改用户
   int updateUser(User user);
   //删除一个用户
   int deleteUser(int id);
}

对应的xml文件中包含所需要用到的增删改查的SQL语句。

<?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=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.bjwl.dao.UserMapper">
    <!--select查询语句：全部查询-->
    <select id="getUserList" resultType="com.bjwl.pojo.User" parameterType="String">
        select * from mybatis1.user
    </select>
    <!--查询语句-->
    <select id="getUserById" parameterType="int" resultType="com.bjwl.pojo.User">
        select * from mybatis1.user where id = #{id}
    </select>
    <!--对象中属性可以直接取出来-->
    <insert id="addUser" parameterType="com.bjwl.pojo.User" >
        insert into mybatis1.user (id,name,pwd) value(#{id},#{name},#{pwd});
    </insert>
    <!--修改数据-->
    <update id="updateUser" parameterType="com.bjwl.pojo.User">
        update mybatis1.user set id=#{id},name=#{name},pwd=#{pwd}  where id = #{id};
    </update>
    <!--删除一条数据-->
    <delete id="deleteUser" parameterType="com.bjwl.pojo.User">
        delete from mybatis1.user where id = #{id}
    </delete>
</mapper>

mybatis核心配置文件：mybatis-config.xml。

该文件配置了 MyBatis 的一些全局信息，包含数据库连接信息和 MyBatis 运行时所需的各种特性，以及设置和影响 MyBatis 行为的一些属性。

<?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/mybatis1?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/bjwl/dao/UserMapper.xml"/>
    </mappers>
</configuration>

util包中的mybatisUtils类

package com.bjwl.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.*;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;

//sqlSessionFactory-->SqlSession
public class MybatisUtils {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            //使用mybatis第一步：获取sqlSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //既然有了sqlSessionFactory,顾名思义，我们就可以从中获得SqlSession的实例
    //SqlSession完全包含了面向数据库执行SQL命令的所有方法
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

编写一个测试类：

下面是固定部分：

package com.bjwl.dao;

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

import javax.swing.plaf.basic.BasicMenuUI;
import java.util.List;

public class UserDaoTest {
    @Test
    public void test(){
        //第一步：获得SqlSession对象
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        try {
            //方式一:getMapper
            UserMapper userDao = sqlSession.getMapper(UserMapper.class);
            List<User> userList = userDao.getUserList();
            //方式二:
            // List<User> userList = sqlSession.selectList("com.bjwl.dao.UserDao.getUserList");
            //遍历一个数组
            for (User user : userList) {
                System.out.println(user);
            }
        }catch (Exception e){
           e.printStackTrace();
        }finally {
            //关闭sqlSession
            sqlSession.close();
        }
    }

 查询数据：

  @Test
    public void getUserById(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.getUserById(1);
        System.out.println(user);
        sqlSession.close();
    }

查询结果：

插入数据：

 @Test
    public void addUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User();
        user.setUsername("rose");
        user.setJobs( "student" );
        user.setPhone("13884520460");
        int rows = sqlSession.insert("com.bjwl.dao"
                    +".UserMapper.addUser", user);
        if(rows>0){
            System.out.println("您成功插入了"+rows+"条数据");
        }else{
            System.out.println("执行插入操作失败！！！");
        }
        //提交事务
        sqlSession.commit();
        //关闭sqlSession
        sqlSession.close();
    }

插入结果：

数据库结果显示：

修改更新：

@Test
    public void updateUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper( UserMapper.class );
        User user = new User();
        user.setId( 3 );
        user.setName( "小头爸爸" );
        user.setPwd( "963258" );
        int rows = sqlSession.update("com.bjwl.dao"
                +".UserMapper.updateUser", user);
        if(rows>0){
            System.out.println("您成功修改了"+rows+"条数据");
        }else{
            System.out.println("执行修改操作失败！！！");
        }
        sqlSession.commit();
        sqlSession.close();
    }

结果图：

数据库更新之后的数据表：

删除数据：

@Test
    public void deleteUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper( UserMapper.class );
        mapper.deleteUser( 4);
        sqlSession.commit();
        sqlSession.close();
    }

结果：

数据库：

测试类全部源码如下：

package com.bjwl.dao;

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

import javax.swing.plaf.basic.BasicMenuUI;
import java.util.List;

public class UserDaoTest {
    @Test
    public void test(){
        //第一步：获得SqlSession对象
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        try {
            //方式一:getMapper
            UserMapper userDao = sqlSession.getMapper(UserMapper.class);
            List<User> userList = userDao.getUserList();
            //方式二:
            // List<User> userList = sqlSession.selectList("com.bjwl.dao.UserDao.getUserList");
            //遍历一个数组
            for (User user : userList) {
                System.out.println("user");
            }
        }catch (Exception e){
           e.printStackTrace();
        }finally {
            //关闭sqlSession
            sqlSession.commit();
            sqlSession.close();
        }
    }
    @Test
    public void getUserById(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.getUserById(1);
        System.out.println(user);
        sqlSession.close();
    }
    //增删改需要提交事务
    @Test
    public void addUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user=new User();
        user.setName( "胡图图" );
        user.setPwd( "258963" );
        //提交事务
        sqlSession.commit();
        //关闭sqlSession
        sqlSession.close();
    }

    @Test
    public void updateUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper( UserMapper.class );
        User user = new User();
        user.setId( 3 );
        user.setName( "小头爸爸" );
        user.setPwd( "963258" );
        int rows = sqlSession.update("com.bjwl.dao"
                +".UserMapper.updateUser", user);
        if(rows>0){
            System.out.println("您成功修改了"+rows+"条数据");
        }else{
            System.out.println("执行修改操作失败！！！");
        }
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void deleteUser(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper( UserMapper.class );
        mapper.deleteUser( 4);
        sqlSession.commit();
        sqlSession.close();
    }
}