Mybatis ResultType如何處理返回類型

更新時(shí)間：2024年01月22日 17:07:51 作者：JoneClassMate

這篇文章主要介紹了Mybatis ResultType如何處理返回類型方式,具有很好的參考價(jià)值,希望對(duì)大家有所幫助,如有錯(cuò)誤或未考慮完全的地方,望不吝賜教

1. 使用resultType返回List<T>

Mapper.xml

<select id="resultType2" resultType="String">
    select
    book_name
    from tb_book
  </select>

service層

List<String> resultType2();

實(shí)現(xiàn)類

    //創(chuàng)建對(duì)象
    private BookMapper bookMapper;
 
 
    /**
     * 給bookMapper set,get方法
     * @return
     */
    public BookMapper getBookMapper() {
        return bookMapper;
    }
 
    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }
 
    @Override
    public List<String> resultType2() {
        return bookMapper.resultType2();
    }

使用junit測(cè)試

package com.jmh.mybatis.service.impl;
 
import com.jmh.mybatis.mapper.BookMapper;
import com.jmh.mybatis.model.Book;
import com.jmh.mybatis.model.BookVo;
import com.jmh.mybatis.service.IBookService;
import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
 
import java.util.List;
import java.util.Map;
import java.util.Set;
 
import static org.junit.Assert.*;
 
public class DemoTest {
    //獲取對(duì)象
    private Book book;
    private IBookService iBookService;
    private SqlSession sqlSession;
 
    @Before
    public void setUp() throws Exception {
        book=new Book();
        sqlSession = MybatisSqlSessionFactory.getSqlsession();
        BookMapper mapper = sqlSession.getMapper(BookMapper.class);
        BookServiceImpl iml=new BookServiceImpl();
        iml.setBookMapper(mapper);
        iBookService= iml;
    }
 
    @After
    public void tearDown() throws Exception {
        sqlSession.commit();
        MybatisSqlSessionFactory.closeSqlsession();
    }
 
 
    @Test
    public void resultType2() {
        List<String> books = iBookService.resultType2();
        for (String b : books) {
            System.out.println(b);
        }
    }
 
}

測(cè)試如下

2. 使用resultType返回單個(gè)對(duì)象

Mapper.xml

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

service層

Book resultType3();

實(shí)現(xiàn)類

    //創(chuàng)建對(duì)象
    private BookMapper bookMapper;
 
 
    /**
     * 給bookMapper set,get方法
     * @return
     */
    public BookMapper getBookMapper() {
        return bookMapper;
    }
 
    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }
 
    @Override
    public Book resultType3() {
        return bookMapper.resultType3();
    }

使用junit測(cè)試

    package com.jmh.mybatis.service.impl;
 
import com.jmh.mybatis.mapper.BookMapper;
import com.jmh.mybatis.model.Book;
import com.jmh.mybatis.model.BookVo;
import com.jmh.mybatis.service.IBookService;
import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
 
import java.util.List;
import java.util.Map;
import java.util.Set;
 
import static org.junit.Assert.*;
 
public class DemoTest {
    //獲取對(duì)象
    private Book book;
    private IBookService iBookService;
    private SqlSession sqlSession;
 
    @Before
    public void setUp() throws Exception {
        book=new Book();
        sqlSession = MybatisSqlSessionFactory.getSqlsession();
        BookMapper mapper = sqlSession.getMapper(BookMapper.class);
        BookServiceImpl iml=new BookServiceImpl();
        iml.setBookMapper(mapper);
        iBookService= iml;
    }
 
    @After
    public void tearDown() throws Exception {
        sqlSession.commit();
        MybatisSqlSessionFactory.closeSqlsession();
    }
 
 
    @Test
    public void resultType3() {
        Book book = iBookService.resultType3();
        System.out.println(book);
    }
 
 
 
}

3. 使用resultType返回List<Map>，適用于多表查詢返回結(jié)果集

mapper接口

需要使用注解才能使用map其實(shí)這個(gè)主要功能也不大將就著用吧

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

mapper.xml

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

service層

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

實(shí)現(xiàn)類

    //創(chuàng)建對(duì)象
    private BookMapper bookMapper;
 
 
    /**
     * 給bookMapper set,get方法
     * @return
     */
    public BookMapper getBookMapper() {
        return bookMapper;
    }
 
    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }
    @Override
    public List<Map<String, Object>> resultType4() {
        return bookMapper.resultType4();
    }

使用junit測(cè)試

package com.jmh.mybatis.service.impl;
 
import com.jmh.mybatis.mapper.BookMapper;
import com.jmh.mybatis.model.Book;
import com.jmh.mybatis.model.BookVo;
import com.jmh.mybatis.service.IBookService;
import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
 
import java.util.List;
import java.util.Map;
import java.util.Set;
 
import static org.junit.Assert.*;
 
public class DemoTest {
    //獲取對(duì)象
    private Book book;
    private IBookService iBookService;
    private SqlSession sqlSession;
 
    @Before
    public void setUp() throws Exception {
        book=new Book();
        sqlSession = MybatisSqlSessionFactory.getSqlsession();
        BookMapper mapper = sqlSession.getMapper(BookMapper.class);
        BookServiceImpl iml=new BookServiceImpl();
        iml.setBookMapper(mapper);
        iBookService= iml;
    }
 
    @After
    public void tearDown() throws Exception {
        sqlSession.commit();
        MybatisSqlSessionFactory.closeSqlsession();
    }
 
 
    @Test
    public void resultType4() {
        List<Map<String, Object>> maps = iBookService.resultType4();
        for (Map<String, Object> map : maps) {
            System.out.println(map);
        }
    }
 
}

4. 使用resultType返回Map<String,Object>，適用于多表查詢返回單個(gè)結(jié)果集

mapper接口

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

mapper.xml

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

service層

Map<String,Object> resultType5();

實(shí)現(xiàn)類

    //創(chuàng)建對(duì)象
    private BookMapper bookMapper;
 
 
    /**
     * 給bookMapper set,get方法
     * @return
     */
    public BookMapper getBookMapper() {
        return bookMapper;
    }
 
    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }
 
    @Override
    public Map<String, Object> resultType5() {
        return bookMapper.resultType5();
    }

使用junit測(cè)試

package com.jmh.mybatis.service.impl;
 
import com.jmh.mybatis.mapper.BookMapper;
import com.jmh.mybatis.model.Book;
import com.jmh.mybatis.model.BookVo;
import com.jmh.mybatis.service.IBookService;
import com.jmh.mybatis.utils.MybatisSqlSessionFactory;
import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
 
import java.util.List;
import java.util.Map;
import java.util.Set;
 
import static org.junit.Assert.*;
 
public class DemoTest {
    //獲取對(duì)象
    private Book book;
    private IBookService iBookService;
    private SqlSession sqlSession;
 
    @Before
    public void setUp() throws Exception {
        book=new Book();
        sqlSession = MybatisSqlSessionFactory.getSqlsession();
        BookMapper mapper = sqlSession.getMapper(BookMapper.class);
        BookServiceImpl iml=new BookServiceImpl();
        iml.setBookMapper(mapper);
        iBookService= iml;
    }
 
    @After
    public void tearDown() throws Exception {
        sqlSession.commit();
        MybatisSqlSessionFactory.closeSqlsession();
}
 
    @Test
    public void resultType5() {
        Map<String, Object> map = iBookService.resultType5();
        System.out.println(map);
    }
}