第1节

用传统mybatis开发

1）statementid写死，编译期发现不了错误
2）参数写死，编译期也没有校验过程
3）代码重复

mapper代理开发方式规则

第一步：配置包扫描，mappers里内容改为如下：

<mappers>
 <!-- 整包扫描 -->
 <package name="com.neuedu.day02.mapper"/>
</mappers>

第二步：
开发接口和xml

第一种 xml方式
满足以下规则：
1）接口名和xml文件名的前缀相同
2）xml的namespace=接口的完全限定名
3）xml的statementid=接口的方法名
4）xml的parametertype=接口方法名的参数类型

5. xml的resulttype=接口方法名的返回值类型

例子如下：

接口UserMapper.java

public interface UserMapper {
//第一种mapper代理，保留xml
public User findUserById(int id);
}

xml

<?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.neuedu.day02.mapper.UserMapper">
<select id="findUserById" parameterType="int" resultType="user">
select * from t_user where user_id = #{user_id}
</select>
</mapper>

调用方式上采用mapper代理调用方式关键代码

      UserMapper userMapper=session.getMapper(UserMapper.class);
      User u=userMapper.findUserById(id);

完整的测试方法

@Override
public User findUserById(int id) throws IOException {
     //第一步读取SqlMapConfig
      //指定文件位置
      //String resource="config/SqlMapConfig.xml";
      //读取资源文件
      //InputStream input=Resources.getResourceAsStream(resource);
      //获取SqlSessionFactory
      //SqlSessionFactory factory= new SqlSessionFactoryBuilder().build(input);
      //获取SqlSession
      SqlSession session=factory.openSession();
      //执行查询
      UserMapper userMapper=session.getMapper(UserMapper.class);
      User u=userMapper.findUserById(id);
      //关闭连接
      session.close();
      return u;
}

第2节

注解方式

第二种 注解方式

注意：相同方法名的注解方式和xml方式只能用一种,xml里不用写对应的statement
几个注解 @Select @Insert @Update @Delete

@Select("select * from t_user where user_id = #{user_id}")
public User selectUserById(int id);
@Insert("insert into t_user(user_id,user_name,user_pwd,user_email,user_idcard,user_power) values (null,#{user_name},#{user_pwd},#{user_email},#{user_idCard},#{user_power})")
public int insertUser(User user);
@Update("update t_user set user_name=#{user_name},user_pwd=#{user_pwd},user_email=#{user_email},user_idcard=#{user_idCard} where user_id=#{user_id}")
public int updateUser(User user);
@Delete("delete  from t_user where user_id=#{user_id}")
public int deleteUser(int id);

 @Test
   public void testSelect() throws IOException{
       IUserDao userDao=new UserDaoImpl(factory);
       User u=userDao.selectUserById(1);
       System.out.println(u.getUser_name());
   }
   @Test
   public void testInsert() throws IOException{
       IUserDao userDao=new UserDaoImpl(factory);
       User user=new User();
       user.setUser_name("chenhao");
       user.setUser_pwd("654321");
       user.setUser_power(0);
       user.setUser_email("chenhao.newedu.com");
       user.setUser_idCard("210101200006061234");
       int count=userDao.insertUser(user);
       System.out.println(count);
   }
   @Test
   public void testUpdate() throws IOException{
       IUserDao userDao=new UserDaoImpl(factory);
       User user=new User();
       user.setUser_id(8);
       user.setUser_name("chenhao");
       user.setUser_pwd("123456");
       user.setUser_email("chenhao.newedu.com");
       user.setUser_idCard("210101200006061234");
       int count=userDao.updateUser(user);
       System.out.println(count);
   }
   @Test
   public void testDelete() throws IOException{
       IUserDao userDao=new UserDaoImpl(factory);
       int count=userDao.deleteUserById(9);
       System.out.println(count);
   }