MYBATIS中resultMap和parameterMap的使用

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当实体类中的属性和数据库中的字段对应是，我们使用resultType和parameterType就可以完成CRUD；

当实体类中的属性和数据库中的字段不对应时，就要用resultMap和parameterMap了。

下面的代码是一个Book实体类和 BOOK_MANAGE数据库，他们的字段是不对应的，以下是用resultMap和parameterMap进行的CRUD操作。

查询时，我们需要返回类型，即用resultMap;

增改删时，我们需要参数类型，即用parameterMap;(这里的删除是根据id删除，实体类和数据库对应的，所以用parameterType效果也一样。)

实体类：

public class Book {
private int id;
private String bookName;
private double bookPrice;

(.....省略get set 方法)
}

BookSql.xml文件：

<?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="my.BookManage">


<resultMap type="Book.dao.Book" id="BookResultMap">
  <id column="id" property="id"/>
  <result column="name" property="bookName"/>
  <result column="price" property="bookPrice"/>
</resultMap>


<parameterMap type="Book.dao.Book" id="BookParameterMap">
  <parameter property="bookName" resultMap="BookResultMap" />
  <parameter property="bookPrice" resultMap="BookResultMap" />
</parameterMap>

<select id="selectAll" resultMap="BookResultMap">
  select * from BOOK_MANAGE
</select>


<select id="selectBookById" parameterType="int" resultMap="BookResultMap">
  select * from BOOK_MANAGE
   where
  id=#{id}
</select>


<delete id="deleteBookById" parameterType="Book.dao.Book">
  delete from BOOK_MANAGE
   where
  id=#{id}
</delete>


<insert id="saveBook" parameterMap="BookParameterMap">
  insert into BOOK_MANAGE
   (ID,NAME,PRICE)
    values
   (Bookmanage_Seq.Nextval,#{bookName},#{bookPrice})
</insert>


<update id="updatePersnById" parameterMap="BookParameterMap">
  update BOOK_MANAGE
   set
    NAME=#{bookName},
    PRICE=#{bookPrice}
   WHERE id=#{id}
</update>
</mapper>

接下来就是servive调用了：

public class BookService {
/**
* 准备工作，获得SqlSessionFactoryBean对象
* @return
* @throws Exception
* @throws Exception
*/
SqlSessionFactory sqlSessionFactory;
public void init() throws Exception{
  String resource = "sqlMapConfig.xml";
  InputStream in = Resources.getResourceAsStream(resource);
  sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
}

/**
* 查询所有Book
* @throws Exception
*/
@Test
public void selectAll() throws Exception{
  init();
  SqlSession session = sqlSessionFactory.openSession();
  List<Book> list = session.selectList("my.BookManage.selectAll");
  session.close();
  for (Iterator iterator = list.iterator(); iterator.hasNext();) {
   Book p = (Book) iterator.next();
   System.out.println(p);
  }
}

/**
* 根据ID查询Book
* @throws Exception
*/
@Test
public void selectBookByID() throws Exception{
  init();
  SqlSession session = sqlSessionFactory.openSession();
  Book book = session.selectOne("my.BookManage.selectBookById",3);
  session.close();
  System.out.println(book);

}

/**
* 根据ID删除Book
* @throws Exception
*/
@Test
public void deleteBookByID() throws Exception{
  init();
  SqlSession session = sqlSessionFactory.openSession();
  int i = session.delete("my.BookManage.deleteBookById",3);
  System.out.println(i);
  //对数据库数据会造成影响的，需要commit
  session.commit();
  session.close();

}

/**
* 保存一个Book
* @throws Exception
*/
@Test
public void saveBook() throws Exception{
  init();
  SqlSession session = sqlSessionFactory.openSession();
  Book b =new Book();
  b.setBookName("BookC");
  b.setBookPrice(15.0);
  int i = session.insert("my.BookManage.saveBook", b);
  System.out.println("插入了"+i+"条数据");
  session.commit();
  session.close();
}

/**
* 根据Id修改一个Book
* @throws Exception
*/
@Test
public void updateBookById() throws Exception{
  init();
  SqlSession session = sqlSessionFactory.openSession();
  Book b =new Book();
  b.setBookName("BookB");
  b.setBookPrice(20.0);
  b.setId(3);
  int i = session.update("my.BookManage.updatePersnById",b);
  System.out.println("修改了"+i+"条数据");
  session.commit();
  session.close();
}

}

出自：http://blog.csdn.net/aquarius_gamus/article/details/37704615

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