public interface UserMapper {
    //查詢user表數(shù)據(jù)
    List<User> selectUser();

    //根據(jù)id查詢用戶
    User selectUserById(int id);

}

<!--
	id : 與mapper層的接口做映射
	parameterType : 參數(shù)類型
	resultType ： 返回的類型對(duì)象
-->
<select id="selectUserById" resultType="com.sin.pojo.User" parameterType="int">
    select * from user where id = #{id}
</select>

// 近似的 JDBC 代碼，非 MyBatis 代碼...
String selectPerson = "SELECT * FROM PERSON WHERE ID=?";
PreparedStatement ps = conn.prepareStatement(selectPerson);
ps.setInt(1,id);

@Test
public void selectUserById(){
    SqlSession session = MyBatisUtil.getSession();
    UserMapper mapper = session.getMapper(UserMapper.class);
    System.out.println(mapper.selectUserById(2));
}

//根據(jù)用戶名和密碼查詢
User findByUserAndPwd(User user);

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

@Test
public void selectByUserAndPwd(){
    SqlSession session = MyBatisUtil.getSession();
    UserMapper mapper = session.getMapper(UserMapper.class);
    User user = new User();
    user.setName("張三");
    user.setPwd("321321");
    System.out.println(mapper.findByUserAndPwd(user));

}

//根據(jù)用戶名和密碼查詢
User findByUserAndPwd2(Map<String,Object> map);

<select id="findByUserAndPwd2" resultType="com.sin.pojo.User"
        parameterType="java.util.Map">
    select * from user where name = #{name} and pwd = #{pwd}
</select>

@Test
public void selectByUserAndPwd2(){
    SqlSession session = MyBatisUtil.getSession();
    UserMapper mapper = session.getMapper(UserMapper.class);
    Map<String,Object> map = new HashMap<>();
    map.put("name","張三");
    map.put("pwd","321321");
    System.out.println(mapper.findByUserAndPwd2(map));

}

//根據(jù)用戶名和密碼查詢
User findByUserAndPwd3(@Param("username") String username, @Param("pwd") String pwd);

<select id="findByUserAndPwd3" resultType="com.sin.pojo.User">
     select * from user where name = #{username} and pwd = #{pwd}
</select>

@Test
public void selectByUserAndPwd3(){
    System.out.println(mapper.findByUserAndPwd3("張三","321321"));
}

<select
  id="selectPerson"
  parameterType="int"
  parameterMap="deprecated"
  resultType="hashmap"
  resultMap="personResultMap"
  flushCache="false"
  useCache="true"
  timeout="10"
  fetchSize="256"
  statementType="PREPARED"
  resultSetType="FORWARD_ONLY">

//添加一條用戶
int addUser(User user);

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

@Test
public void addUser(){
    SqlSession session = MyBatisUtil.getSession();
    UserMapper mapper = session.getMapper(UserMapper.class);
    User user = new User(5,"王五","123456");
    System.out.println(mapper.addUser(user));
    session.commit();//提交事務(wù),重點(diǎn)!不寫的話不會(huì)提交到數(shù)據(jù)庫(kù)
}

//修改一個(gè)用戶
int updateUser(User user);

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

@Test
public void testUpdateUser(){
    SqlSession session = MyBatisUtil.getSession();
    UserMapper mapper = session.getMapper(UserMapper.class);
    User user = mapper.selectUserById(1);
    user.setName("趙六");
    user.setPwd("123456");
    int i = mapper.updateUser(user);
    System.out.println(mapper.selectUserById(1));
    session.commit();//提交事務(wù)，
    session.close();
}

//根據(jù)id刪除用戶
int deleteUserById(int id);

<delete id="deleteUserById" parameterType="com.sin.pojo.User">
    delete  from user where id = #{id};
</delete>

@Test
public void deleteUesrById(){
    SqlSession session = MyBatisUtil.getSession();
    UserMapper mapper = session.getMapper(UserMapper.class);
    System.out.println(mapper.deleteUserById(5));
    session.commit();//提交事務(wù)，
    List<User> users = mapper.selectUser();
    for (User user: users){
        System.out.println(user);
    }

    session.close();
}

<insert
  id="insertAuthor"
  parameterType="com.sin.pojo.User"
  flushCache="true"
  statementType="PREPARED"
  keyProperty=""
  keyColumn=""
  useGeneratedKeys=""
  timeout="20">

<update
  id="updateAuthor"
  parameterType="com.sin.pojo.User"
  flushCache="true"
  statementType="PREPARED"
  timeout="20">

<delete
  id="deleteAuthor"
  parameterType="com.sin.pojo.User"
  flushCache="true"
  statementType="PREPARED"
  timeout="20">

<selectKey
  keyProperty="id"
  resultType="int"
  order="BEFORE"
  statementType="PREPARED">