Mybatis对MySQL数据库的增删改查

首先，需要注意的是 环境：先装JDK，再装maven（注意顺序)

用idea创建的maven项目结构如下（箭头顺序对应下文）：

父工程pom.xml文件用来配置依赖，如下所示

<?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>
    <!--父工程，创建项目自动有的-->
    <groupId>com.Juff</groupId>
    <artifactId>Mybatis-Study</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>mybatis-01</module>
    </modules>

    <!--导入依赖，需要自敲-->
    <dependencies>
        <!--1首先需要：jdbc驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
        </dependency>
        <!-- 2、第二点：mybatis-->
        <!--  MyBatis 是一款优秀的持久层框架，它支持自定义 SQL、存储过程以及高级映射。MyBatis-->
        <!-- 免除了几乎所有的 JDBC 代码以及设置参数和获取结果集的工作.MyBatis 可以通过简单的 XML-->
        <!-- 或注解来配置和映射原始类型、接口和 Java POJO（Plain Old Java Objects，普通老式 Java 对象）-->
        <!-- 为数据库中的记录-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <!--3、第三点：junit   单元测试框架-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

    <!--最后这个是控制整个项目导出到target才能运行起来-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>

子工程pom.xml的配置如下：

<?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">
    <parent>
        <artifactId>Mybatis-Study</artifactId>
        <groupId>com.Juff</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>mybatis-01</artifactId>

 <!--上面是创建项目自动有的，下面是控制整个项目导出到target才能运行起来（虽然父过程pom.xml已经配置了，这里以防万一，再加上）-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>

接下来是mybatis-config.xml,用来配置连接数据库的相关信息

<?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">


<!--mybatis里面的具体配置，控制链接数据库的操作-->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <!--这里useSSL取值为false，否则会报错-->
                <property name="url"
                          value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="199829."/>
            </dataSource>
        </environment>
    </environments>

    <!-- 下面的mappers要一一包含对应实体类的Mapper，表示联系对应的视图类-->
    <mappers>
        <mapper resource="com/Juff/dao/UserMapper.xml"/>
    </mappers>

</configuration>

创建pojo层

User.java

package com.Juff.pojo;

//POJO（Plain Ordinary Java Object）简单的Java对象，实际就是普通JavaBeans
//0 其中有一些属性及其getter setter方法的类,没有业务逻辑
//有一个简单的运算属性也是可以的,但不允许有业务方法，也不能携带有connection之类的方法
//POJO实质上可以理解为简单的实体类，顾名思义POJO类的作用是方便程序员使用数据库中的数据表
//可以很方便的将POJO类当做对象来进行使用，当然也是可以方便的调用其get,set方法

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 + '\'' +
                '}';
    }
}

创建dao层

UserMapper.java（相当于UserDao.java,名字不一样而已）

package com.Juff.dao;

import com.Juff.pojo.User;

import java.util.List;
import java.util.Map;

//DAO (DataAccessobjects 数据存取对象)是指位于业务逻辑和持久化数据之间实现对持久化数据的访问。
//通俗来讲，就是将数据库操作都封装起来.对外提供相应的接口

public interface UserMapper {

    List<User> getUserLike(String value);
    //查询全部用户

    List<User> getUserList();

    //根据id查询用户

    User getUserById(int id);

    User getUserById2(Map<String, Object> map);

    //插入用户

    int addUser(User uer);

    //万能Map

    int addUser2(Map<String,Object> map);

    //修改用户

    int updateUser(User uer);

    //s删除用户

    int deleteUser(int id);
}

UserMapper.xml（用来实现UserMapper.java的具体业务方法）

<?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">
<!--绑定-->
<mapper namespace="com.Juff.dao.UserMapper">

    <select id="getUserLike" resultType="com.Juff.pojo.User">
--         select * from  mybatis.user where name like #{value}  这里需要注意，sql连注释都会运行的，注释没用！！！
        select * from  mybatis.user where name like "%"#{value}"%"

    </select>

    <!--相当于实现类UserImpl,实现对应的接口-->
    <select id="getUserList" resultType="com.Juff.pojo.User">
--          SQL语句
         select * from mybatis.user
     </select>

    <select id="getUserById" parameterType="int" resultType="com.Juff.pojo.User">
        select * from mybatis.user where id=#{id};
    </select>

    <select id="getUserById2" parameterType="map" resultType="com.Juff.pojo.User">
        select * from mybatis.user where id=#{helloId};
    </select>


    <insert id="addUser" parameterType="com.Juff.pojo.User">
        insert  into mybatis.user(id ,name,pwd) values (#{id},#{name},#{pwd});
    </insert>

    <insert id="addUser2" parameterType="map">
        insert  into mybatis.user(id,name,pwd) values (#{userId},#{userName},#{password});
    </insert>

    <update id="updateUser" parameterType="com.Juff.pojo.User">
      update mybatis.user set name =#{name},pwd=#{pwd} where id=#{id};
    </update>

    <delete id="deleteUser" parameterType="com.Juff.pojo.User">
      delete from mybatis.user  where id=#{id};
    </delete>
</mapper>

创建utils层

MybatisUtils.java

package com.Juff.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;

//sqlSessionFactory --> sqlSession
//MybatisUtils,封装SQLSession的创建和关闭

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 的实例了
    // SqlSession 完全包含了面向数据库执行 SQL 命令所需的所有方法
    public static SqlSession getSqlSession() {
        return sqlSessionFactory.openSession();
    }
}

最后测试

UserMapperTest.java

package com.Juff.dao;

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

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class UserMapperTest {
    @Test
    public void test() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        try {
//        方式一:推荐
            UserMapper userDao = sqlSession.getMapper(UserMapper.class);
            List<User> userList = userDao.getUserList();

//        方式二:以前的做法
//        List<User> userList=sqlSession.selectList("com.Juff.dao.UserDao.getUserList");

            for (User user : userList) {
                System.out.println(user);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            sqlSession.close();
        }
    }

    @Test
    public void getUserLike() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
//        List<User> userList = mapper.getUserLike("%俊%");
        List<User> userList = mapper.getUserLike("俊");
        for (User user : userList) {
            System.out.println(user);
        }
        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();
    }

    @Test
    public void getUserById2() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("helloId", 1);
        System.out.println(mapper.getUserById2(map));
        sqlSession.close();
    }


    @Test
    public void addUser() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int res = mapper.addUser(new User(4, "God", "10096"));
        if (res > 0) {
            System.out.println("insert success!");
        }
        //增删改需要提交事务
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void addUser2() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("userId", 5);
        map.put("userName", "Hello");
        map.put("password", "2222333");
        mapper.addUser2(map);
        //增删改需要提交事务
        sqlSession.commit();
        System.out.println("insert success");
        sqlSession.close();
    }

    @Test
    public void updateUser() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.updateUser(new User(4, "God", "233233"));
        //增删改需要提交事务
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void deleteUser() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.deleteUser(4);
        //增删改需要提交事务
        sqlSession.commit();
        sqlSession.close();
    }
}

以上5大步即可完成一个Mybatis的增删改查，如若需要视频，这便是——>：入口（亲测有效）