mybatis关联关系映射

1.先用逆向生成工具生成t_hibernate_order、t_hibernate_order_item

这两张表对应的model与mapper

2.为了不破坏实体类原有的封装，新建立两个实体类进行对应关系的映射

OrderVo

package com.sjy.model.vo;

import com.sjy.model.Order;
import com.sjy.model.OrderItem;

import java.util.ArrayList;
import java.util.List;

public class OrderVo extends Order {
    private List orderItem=new ArrayList<>();

    @Override
    public String toString() {
        return "OrderVo{" +
                "orderItem=" + orderItem +
                '}';
    }

    public List getOrderItem() {
        return orderItem;
    }

    public void setOrderItem(List orderItem) {
        this.orderItem = orderItem;
    }
}

OrderItemVo

package com.sjy.model.vo;

import com.sjy.model.Order;
import com.sjy.model.OrderItem;

public class OrderItemVo extends OrderItem {
    private Order order;

    public Order getOrder() {
        return order;
    }

    public void setOrder(Order order) {
        this.order = order;
    }

    @Override
    public String toString() {
        return "OrderItemVo{" +
                "order=" + order +
                '}';
    }
}

3.在对应的mapper.xml中进行一对多的配置

orderMapper.xml

orderItemMapper.xml

 4.分别写入sql语句进行验证

orderItemMapper.xml

  
    select * from t_hibernate_order t1,t_hibernate_order_item t2
    where t1.order_id=t2.oid and t2.order_item_id=#{orderItemId}
   
orderMapper.xml
 
 
    select * from t_hibernate_order t1,t_hibernate_order_item t2 where t1.order_id=t2.oid and t1.order_id=#{orderId}
  

 5.建立一对多的service接口

package com.sjy.service;

import com.sjy.model.vo.OrderItemVo;
import com.sjy.model.vo.OrderVo;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface oneToManyService {

    List selectByOrderItemId(Integer orderItemId);
    List selectByOrderId(Integer orderId);
}

6.实现 接口

package com.sjy.service.impl;

import com.sjy.mapper.OrderItemMapper;
import com.sjy.mapper.OrderMapper;
import com.sjy.model.vo.OrderItemVo;
import com.sjy.model.vo.OrderVo;
import com.sjy.service.OneToManyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
@Service
public class oneToManyServiceImpl implements oneToManyService {
    @Autowired
    private OrderMapper orderMapper;

    @Autowired
    private OrderItemMapper orderItemMapper;

    @Override
    public List selectByOrderItemId(Integer orderItemId) {
        return orderItemMapper.selectByOrderItemId(orderItemId);
    }

    @Override
    public List selectByOrderId(Integer orderId) {
        return orderMapper.selectByOrderId(orderId);
    }
}

7.测试

package com.sjy.service.impl;

import com.sjy.SpringbaseTest;
import com.sjy.model.OrderItem;
import com.sjy.model.vo.OrderItemVo;
import com.sjy.model.vo.OrderVo;
import com.sjy.service.OneToManyService;
import junit.framework.TestCase;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.util.List;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"classpath:applicationContext.xml"})
public class oneToManyServiceImplTest extends SpringbaseTest {

@Autowired
private oneToManyService oneToManyService;

@Test
    public void testSelectByOrderItemId() {
        OrderItemVo orderItemVo = oneToManyService.selectByOrderItemId(36).get(0);
        System.out.println(orderItemVo);
        System.out.println(orderItemVo.getOrder());
    }

    @Test
    public void testSelectByOrderId() {
        List vo=oneToManyService.selectByOrderId(8);
        OrderVo orderVo=vo.get(0);
        System.out.println(orderVo);
        for (OrderItem orderItem : orderVo.getOrderItem()) {
            System.out.println(orderItem);
        }
    }
}

结果

1.先用逆向生成工具生成t_hibernate_book t_hibernate_category t_hibernate_book_category

三个表的mapper和mapper.xml文件

2.建立vo类 

HbookVo

package com.sjy.model.vo;

import com.sjy.model.Category;
import com.sjy.model.Hbook;

import java.util.ArrayList;
import java.util.List;


public class HbookVo extends Hbook {
    private List categories = new ArrayList<>();

    public List getCategories() {
        return categories;
    }

    public void setCategories(List categories) {
        this.categories = categories;
    }
}

 CategoryVo 

package com.sjy.model.vo;

import com.sjy.model.Category;
import com.sjy.model.Hbook;

import java.util.ArrayList;
import java.util.List;


 
public class CategoryVo extends Category {
    private List hbooks = new ArrayList<>();

    public List getHbooks() {
        return hbooks;
    }

    public void setHbooks(List hbooks) {
        this.hbooks = hbooks;
    }
}

3.在中间表t_hibernate_book_category的mapper.xml 文件中配置多对多映射关系

4.在 t_hibernate_book_category的mapper.xml 文件中添加sql语句

  
select * from t_hibernate_book b,t_hibernate_book_category bc,t_hibernate_category c
     where b.book_id = bc.bid and bc.cid = c.category_id and b.book_id = #{bookId}
 
   
select * from t_hibernate_book b,t_hibernate_book_category bc,t_hibernate_category c
     where b.book_id = bc.bid and bc.cid = c.category_id and c.category_id=#{cid}
   

5.HbookCategoryMapper.java

package com.sjy.mapper;

import com.sjy.model.HbookCategory;
import com.sjy.model.vo.CategoryVo;
import com.sjy.model.vo.HbookVo;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

@Repository
public interface HbookCategoryMapper {
    int deleteByPrimaryKey(Integer bcid);

    int insert(HbookCategory record);

    int insertSelective(HbookCategory record);

    HbookCategory selectByPrimaryKey(Integer bcid);

    int updateByPrimaryKeySelective(HbookCategory record);

    int updateByPrimaryKey(HbookCategory record);

    HbookVo queryByBookId(@Param("bookId") Integer bookId);

    CategoryVo queryByCid(@Param("cid") Integer cid);


}

6.多对多的接口 Many2ManyService

package com.sjy.service;

import com.sjy.model.vo.CategoryVo;
import com.sjy.model.vo.HbookVo;
import org.apache.ibatis.annotations.Param;


public interface Many2ManyService {
    HbookVo queryByBookId(Integer bookId);

    CategoryVo queryByCid(Integer cid);
}

7.实现接口Many2ManyServiceImpl 

package com.sjy.service.impl;

import com.sjy.mapper.HbookCategoryMapper;
import com.sjy.model.vo.CategoryVo;
import com.sjy.model.vo.HbookVo;
import com.sjy.service.Many2ManyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


@Service
public class Many2ManyServiceImpl implements Many2ManyService {
    @Autowired
    private HbookCategoryMapper hbookCategoryMapper;
    @Override
    public HbookVo queryByBookId(Integer bookId) {
        return hbookCategoryMapper.queryByBookId(bookId);
    }

    @Override
    public CategoryVo queryByCid(Integer cid) {
        return hbookCategoryMapper.queryByCid(cid);
    }
}

8.测试

package com.sjy.service.impl;

import com.sjy.SpringbaseTest;
import com.sjy.model.Category;
import com.sjy.model.Hbook;
import com.sjy.model.vo.CategoryVo;
import com.sjy.model.vo.HbookVo;
import com.sjy.service.Many2ManyService;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;

import static org.junit.Assert.*;


public class Many2ManyServiceImplTest extends SpringbaseTest {
    @Autowired
    private Many2ManyService many2ManyService;

    @Test
    public void queryByBookId() {
        HbookVo hbookVo = many2ManyService.queryByBookId(8);
        System.out.println(hbookVo);
        for (Category category : hbookVo.getCategories()) {
            System.out.println(category);
        }
    }

    @Test
    public void queryByCid() {
        CategoryVo categoryVo = many2ManyService.queryByCid(8);
        System.out.println(categoryVo);
        for (Hbook hbook : categoryVo.getHbooks()) {
            System.out.println(hbook);
        }

    }

}

 结果