CREATE DATABASE `mybatis`;

USE `mybatis`;

DROP TABLE IF EXISTS `user`;

CREATE TABLE `user` (
`id` int(20) 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,'王二','123456'),(2,'张三','abcdef'),(3,'李四','987654');

2、导入pom.xml文件?

<dependencies>
    <!--mysql驱动-->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.46</version>
    </dependency>

    <!--mybatis-->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.2</version>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.10</version>
    </dependency>

    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
</dependencies>

3、解决Maven静态资源过滤问题

<resources>
   <resource>
       <directory>src/main/java</directory>
       <includes>
           <include>**/*.properties</include>
           <include>**/*.xml</include>
       </includes>
       <filtering>false</filtering>
   </resource>
   <resource>
       <directory>src/main/resources</directory>
       <includes>
           <include>**/*.properties</include>
           <include>**/*.xml</include>
       </includes>
       <filtering>false</filtering>
   </resource>
</resources>

4、编写MyBatis核心配置文件

<?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">

<!--核心配置文件-->
<configuration>
<environments default="development">
    <environment id="development">
        <transactionManager type="JDBC"/>
        <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <!--useUnicode使用Unicode中文编码-->
            <!--不加这useUnicode=true&amp;characterEncoding=UTF-8存中文进去是问号-->
            <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&amp;characterEncoding=UTF-8"/>
            <property name="username" value="root"/>
            <property name="password" value="12345"/>
        </dataSource>
    </environment>
</environments>
<mappers>
    <mapper resource="com/dao/UseMapper.xml"></mapper>
</mappers>
</configuration>

5、编写MyBatis工具类

public class MybatisUtils {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        InputStream inputStream = null;
        try {
            //获得SqlSessionFactory对象
            String resource = "mybatis-config.xml";
            inputStream = Resources.getResourceAsStream(resource);
           sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
    // SqlSession 提供了在数据库执行 org.apache.ibatis.jdbc.SQL 命令所需的所有方法。
    public static SqlSession getSqlSession(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession;
    }
}

6、创建实体类

@AllArgsConstructor
@NoArgsConstructor
@Data
public class User {
    private int id;
    private String name;
    private String password;
}

7、编写Mapper.xml配置文件

配置文件中namespace中的名称为对应Mapper接口或者Dao接口的完整包名,必须一致！

<?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.dao.UserMapper">
   
</mapper>

二、查询操作

1、在UserMapper中添加对应方法

public interface UserMapper {
   //使用@Param 根据密码和名字查询用户
   User selectUserByNP(@Param("username") String username,@Param("pwd") String pwd);
   //使用Map 根据密码和名字查询用户
   User selectUserByNP2(Map<String,Object> map);
}

2、在UserMapper.xml中添加Select语句

   <select id="selectUserByNP" resultType="com.pojo.User">
     select * from user where name = #{username} and pwd = #{pwd}
   </select>

   <select id="selectUserByNP2" parameterType="map" resultType="com.pojo.User">
     select * from user where name = #{username} and pwd = #{pwd}
   </select>

3、测试类中测试

    @Test
    public void selectUserByNP2(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        Map<String, Object> map = new HashMap();
        map.put("id",4);
        map.put("name","小原");
        User user = mapper.selectUserByNP2(map);
        System.out.println(user);
        sqlSession.close();
    }

4、说明

在接口方法的参数前加 @Param属性，Sql语句编写的时候，直接取@Param中设置的值即可，不需要单独设置参数类型。

在接口方法中，参数直接传递Map，Map的 key 为 sql中取的值即可，没有顺序要求！

?三、添加操作

1、在UserMapper接口中添加对应的方法

// 添加一个用户
int addUser(User user);

2、在UserMapper.xml中添加insert语句

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

3、测试

注意点：增、删、改操作需要提交事务！

@Test
public void testAddUser() {
   SqlSession session = MybatisUtils.getSession();
   UserMapper mapper = session.getMapper(UserMapper.class);
   User user = new User(5,"王五","zxcvbn");
   int i = mapper.addUser(user);
   System.out.println(i);
   session.commit(); //提交事务,重点!不写的话不会提交到数据库
   session.close();
}

四、修改操作

1、在UserMapper接口中添加对应的方法

//修改一个用户
int updateUser(User user);

?2、在UserMapper.xml中添加update语句

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

3、测试?

@Test
public void testUpdateUser() {
   SqlSession session = MybatisUtils.getSession();
   UserMapper mapper = session.getMapper(UserMapper.class);
   User user = mapper.selectUserById(1);
   user.setPwd("asdfgh");
   int i = mapper.updateUser(user);
   System.out.println(i);
   session.commit(); //提交事务,重点!不写的话不会提交到数据库
   session.close();
}

五、删除操作

1、在UserMapper接口中添加对应的方法

//根据id删除用户
int deleteUser(int id);

?2、在UserMapper.xml中添加delete语句

<delete id="deleteUser" parameterType="int">
  delete from user where id = #{id}
</delete>

3、测试

@Test
public void testDeleteUser() {
   SqlSession session = MybatisUtils.getSession();
   UserMapper mapper = session.getMapper(UserMapper.class);
   int i = mapper.deleteUser(5);
   System.out.println(i);
   session.commit(); //提交事务,重点!不写的话不会提交到数据库
   session.close();
}