Mybatis ResultType处理返回类型

目录

 1. 使用resultType返回List

 2. 使用resultType返回单个对象

3. 使用resultType返回List，适用于多表查询返回结果集 

 4. 使用resultType返回Map，适用于多表查询返回单个结果集,object>

---

 1. 使用resultType返回List<T>

• Mapper.xml 

1.  
   <select id="resultType2" resultType="String">
2.  
   select
3.  
   book_name
4.  
   from tb_book
5.  
   </select>

•  service层

List<String> resultType2();

• 实现类

1.  
   //创建对象
2.  
   private BookMapper bookMapper;
3.  
    
4.  
    
5.  
   /**
6.  
   * 给bookMapper set,get方法
7.  
   * @return
8.  
   */
9.  
   public BookMapper getBookMapper() {
10.  
    return bookMapper;
11.  
    }
12.  
     
13.  
    public void setBookMapper(BookMapper bookMapper) {
14.  
    this.bookMapper = bookMapper;
15.  
    }
16.  
     
17.  
    @Override
18.  
    public List<String> resultType2() {
19.  
    return bookMapper.resultType2();
20.  
    }

•  使用junit测试

1.  
   package com.jmh.mybatis.service.impl;
2.  
    
3.  
   import com.jmh.mybatis.mapper.BookMapper;
4.  
   import com.jmh.mybatis.model.Book;
5.  
   import com.jmh.mybatis.model.BookVo;
6.  
   import com.jmh.mybatis.service.IBookService;
7.  
   import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
8.  
   import org.apache.ibatis.annotations.MapKey;
9.  
   import org.apache.ibatis.session.SqlSession;
10.  
    import org.junit.After;
11.  
    import org.junit.Before;
12.  
    import org.junit.Test;
13.  
     
14.  
    import java.util.List;
15.  
    import java.util.Map;
16.  
    import java.util.Set;
17.  
     
18.  
    import static org.junit.Assert.*;
19.  
     
20.  
    public class DemoTest {
21.  
    //获取对象
22.  
    private Book book;
23.  
    private IBookService iBookService;
24.  
    private SqlSession sqlSession;
25.  
     
26.  
    @Before
27.  
    public void setUp() throws Exception {
28.  
    book=new Book();
29.  
    sqlSession = MybatisSqlSessionFactory.getSqlsession();
30.  
    BookMapper mapper = sqlSession.getMapper(BookMapper.class);
31.  
    BookServiceImpl iml=new BookServiceImpl();
32.  
    iml.setBookMapper(mapper);
33.  
    iBookService= iml;
34.  
    }
35.  
     
36.  
    @After
37.  
    public void tearDown() throws Exception {
38.  
    sqlSession.commit();
39.  
    MybatisSqlSessionFactory.closeSqlsession();
40.  
    }
41.  
     
42.  
     
43.  
    @Test
44.  
    public void resultType2() {
45.  
    List<String> books = iBookService.resultType2();
46.  
    for (String b : books) {
47.  
    System.out.println(b);
48.  
    }
49.  
    }
50.  
     
51.  
    }

•  测试如下

 2. 使用resultType返回单个对象

• Mapper.xml 

1.  
   <select id="resultType3" resultType="com.jmh.mybatis.model.Book">
2.  
   select
3.  
   <include refid="Base_Column_List" />
4.  
   from tb_book where book_id=306
5.  
   </select>

•  service层

Book resultType3();

•  实现类

1.  
   //创建对象
2.  
   private BookMapper bookMapper;
3.  
    
4.  
    
5.  
   /**
6.  
   * 给bookMapper set,get方法
7.  
   * @return
8.  
   */
9.  
   public BookMapper getBookMapper() {
10.  
    return bookMapper;
11.  
    }
12.  
     
13.  
    public void setBookMapper(BookMapper bookMapper) {
14.  
    this.bookMapper = bookMapper;
15.  
    }
16.  
     
17.  
    @Override
18.  
    public Book resultType3() {
19.  
    return bookMapper.resultType3();
20.  
    }

•  使用junit测试

1.  
   package com.jmh.mybatis.service.impl;
2.  
    
3.  
   import com.jmh.mybatis.mapper.BookMapper;
4.  
   import com.jmh.mybatis.model.Book;
5.  
   import com.jmh.mybatis.model.BookVo;
6.  
   import com.jmh.mybatis.service.IBookService;
7.  
   import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
8.  
   import org.apache.ibatis.annotations.MapKey;
9.  
   import org.apache.ibatis.session.SqlSession;
10.  
    import org.junit.After;
11.  
    import org.junit.Before;
12.  
    import org.junit.Test;
13.  
     
14.  
    import java.util.List;
15.  
    import java.util.Map;
16.  
    import java.util.Set;
17.  
     
18.  
    import static org.junit.Assert.*;
19.  
     
20.  
    public class DemoTest {
21.  
    //获取对象
22.  
    private Book book;
23.  
    private IBookService iBookService;
24.  
    private SqlSession sqlSession;
25.  
     
26.  
    @Before
27.  
    public void setUp() throws Exception {
28.  
    book=new Book();
29.  
    sqlSession = MybatisSqlSessionFactory.getSqlsession();
30.  
    BookMapper mapper = sqlSession.getMapper(BookMapper.class);
31.  
    BookServiceImpl iml=new BookServiceImpl();
32.  
    iml.setBookMapper(mapper);
33.  
    iBookService= iml;
34.  
    }
35.  
     
36.  
    @After
37.  
    public void tearDown() throws Exception {
38.  
    sqlSession.commit();
39.  
    MybatisSqlSessionFactory.closeSqlsession();
40.  
    }
41.  
     
42.  
     
43.  
    @Test
44.  
    public void resultType3() {
45.  
    Book book = iBookService.resultType3();
46.  
    System.out.println(book);
47.  
    }
48.  
     
49.  
     
50.  
     
51.  
    }

3. 使用resultType返回List<Map>，适用于多表查询返回结果集 

• mapper接口 

    需要使用注解才能使用map其实这个主要功能也不大 将就着用吧

1.  
   @MapKey("id")
2.  
   List<Map<String,Object>> resultType4();

• mapper.xml 

1.  
   <select id="resultType4" resultType="java.util.Map">
2.  
   select book_id,price,book_name from tb_book
3.  
   </select>

•  service层

List<Map<String,Object>> resultType4();

•  实现类

1.  
   //创建对象
2.  
   private BookMapper bookMapper;
3.  
    
4.  
    
5.  
   /**
6.  
   * 给bookMapper set,get方法
7.  
   * @return
8.  
   */
9.  
   public BookMapper getBookMapper() {
10.  
    return bookMapper;
11.  
    }
12.  
     
13.  
    public void setBookMapper(BookMapper bookMapper) {
14.  
    this.bookMapper = bookMapper;
15.  
    }
16.  
    @Override
17.  
    public List<Map<String, Object>> resultType4() {
18.  
    return bookMapper.resultType4();
19.  
    }

•  使用junit测试

1.  
   package com.jmh.mybatis.service.impl;
2.  
    
3.  
   import com.jmh.mybatis.mapper.BookMapper;
4.  
   import com.jmh.mybatis.model.Book;
5.  
   import com.jmh.mybatis.model.BookVo;
6.  
   import com.jmh.mybatis.service.IBookService;
7.  
   import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
8.  
   import org.apache.ibatis.annotations.MapKey;
9.  
   import org.apache.ibatis.session.SqlSession;
10.  
    import org.junit.After;
11.  
    import org.junit.Before;
12.  
    import org.junit.Test;
13.  
     
14.  
    import java.util.List;
15.  
    import java.util.Map;
16.  
    import java.util.Set;
17.  
     
18.  
    import static org.junit.Assert.*;
19.  
     
20.  
    public class DemoTest {
21.  
    //获取对象
22.  
    private Book book;
23.  
    private IBookService iBookService;
24.  
    private SqlSession sqlSession;
25.  
     
26.  
    @Before
27.  
    public void setUp() throws Exception {
28.  
    book=new Book();
29.  
    sqlSession = MybatisSqlSessionFactory.getSqlsession();
30.  
    BookMapper mapper = sqlSession.getMapper(BookMapper.class);
31.  
    BookServiceImpl iml=new BookServiceImpl();
32.  
    iml.setBookMapper(mapper);
33.  
    iBookService= iml;
34.  
    }
35.  
     
36.  
    @After
37.  
    public void tearDown() throws Exception {
38.  
    sqlSession.commit();
39.  
    MybatisSqlSessionFactory.closeSqlsession();
40.  
    }
41.  
     
42.  
     
43.  
    @Test
44.  
    public void resultType4() {
45.  
    List<Map<String, Object>> maps = iBookService.resultType4();
46.  
    for (Map<String, Object> map : maps) {
47.  
    System.out.println(map);
48.  
    }
49.  
    }
50.  
     
51.  
    }

 4. 使用resultType返回Map<String,Object>，适用于多表查询返回单个结果集

•  mapper接口

1.  
   @MapKey("id")
2.  
   Map<String,Object> resultType5();

• mapper.xml 

1.  
   <select id="resultType5" resultType="java.util.Map">
2.  
   select book_id,price from tb_book
3.  
   </select>

•  service层

Map<String,Object> resultType5();

•  实现类

1.  
   //创建对象
2.  
   private BookMapper bookMapper;
3.  
    
4.  
    
5.  
   /**
6.  
   * 给bookMapper set,get方法
7.  
   * @return
8.  
   */
9.  
   public BookMapper getBookMapper() {
10.  
    return bookMapper;
11.  
    }
12.  
     
13.  
    public void setBookMapper(BookMapper bookMapper) {
14.  
    this.bookMapper = bookMapper;
15.  
    }
16.  
     
17.  
    @Override
18.  
    public Map<String, Object> resultType5() {
19.  
    return bookMapper.resultType5();
20.  
    }

•  使用junit测试

1.  
   package com.jmh.mybatis.service.impl;
2.  
    
3.  
   import com.jmh.mybatis.mapper.BookMapper;
4.  
   import com.jmh.mybatis.model.Book;
5.  
   import com.jmh.mybatis.model.BookVo;
6.  
   import com.jmh.mybatis.service.IBookService;
7.  
   import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
8.  
   import org.apache.ibatis.annotations.MapKey;
9.  
   import org.apache.ibatis.session.SqlSession;
10.  
    import org.junit.After;
11.  
    import org.junit.Before;
12.  
    import org.junit.Test;
13.  
     
14.  
    import java.util.List;
15.  
    import java.util.Map;
16.  
    import java.util.Set;
17.  
     
18.  
    import static org.junit.Assert.*;
19.  
     
20.  
    public class DemoTest {
21.  
    //获取对象
22.  
    private Book book;
23.  
    private IBookService iBookService;
24.  
    private SqlSession sqlSession;
25.  
     
26.  
    @Before
27.  
    public void setUp() throws Exception {
28.  
    book=new Book();
29.  
    sqlSession = MybatisSqlSessionFactory.getSqlsession();
30.  
    BookMapper mapper = sqlSession.getMapper(BookMapper.class);
31.  
    BookServiceImpl iml=new BookServiceImpl();
32.  
    iml.setBookMapper(mapper);
33.  
    iBookService= iml;
34.  
    }
35.  
     
36.  
    @After
37.  
    public void tearDown() throws Exception {
38.  
    sqlSession.commit();
39.  
    MybatisSqlSessionFactory.closeSqlsession();
40.  
    }
41.  
     
42.  
    @Test
43.  
    public void resultType5() {
44.  
    Map<String, Object> map = iBookService.resultType5();
45.  
    System.out.println(map);
46.  
    }
47.  
    }

---

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