您好,登錄后才能下訂單哦!
這篇文章主要介紹了SpringBoot Data JPA關(guān)聯(lián)表查詢的示例分析,具有一定借鑒價(jià)值,感興趣的朋友可以參考下,希望大家閱讀完這篇文章之后大有收獲,下面讓小編帶著大家一起了解一下。
SpringBoot Data JPA實(shí)現(xiàn) 一對(duì)多、多對(duì)一關(guān)聯(lián)表查詢
開發(fā)環(huán)境
IDEA 2017.1
Java1.8
SpringBoot 2.0
MySQL 5.X
功能需求
通過關(guān)聯(lián)關(guān)系查詢商店Store中所有的商品Shop,商店對(duì)商品一對(duì)多,商品對(duì)商店多對(duì)一,外鍵 store_id存在于多的一方。使用數(shù)據(jù)庫(kù)的內(nèi)連接語(yǔ)句。
表結(jié)構(gòu)
tb_shop
tb_store
實(shí)體類,通過注解實(shí)現(xiàn)
1.商店類Store.java
package com.gaolei.Entity; import javax.persistence.*; import java.util.HashSet; import java.util.Set; /** * Created by GaoLei on 2018/6/25. */ @Entity @Table(name = "tb_store") public class Store { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer id;//商鋪號(hào) private String name;//商鋪姓名 private String address;//商鋪地址 private int tel ;//商鋪聯(lián)系 private String info;//商鋪信息 @OneToMany(cascade = CascadeType.ALL,mappedBy = "store") private Set<Shop> shops = new HashSet<Shop>(); // 省略set()和get()方法; }
商品類Shop.java
package com.gaolei.Entity; import javax.persistence.*; import java.util.HashSet; import java.util.Set; /** * Created by GaoLei on 2018/6/25. */ @Entity @Table(name = "tb_shop") public class Shop { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer id ; //商品id private String name;//商品名 private int price;// 商品價(jià)格 private int num;//商品數(shù)量 private String info;//商品信息 @ManyToOne @JoinColumn(name = "store_id")//外鍵 private Store store; // 省略set()和get()方法; }
StoreDao.java
CrudRepository 接口繼承于 Repository 接口,并新增了簡(jiǎn)單的增、刪、查等方法。其中封裝好了很多的方法,這里不再概述,自行百度,這里通過自定義HQL語(yǔ)句完成復(fù)雜的操作。
package com.gaolei.Dao; import com.gaolei.Entity.Store; import org.springframework.data.jpa.repository.Query; import org.springframework.data.repository.CrudRepository; import org.springframework.stereotype.Repository; import java.util.List; /** * Created by GaoLei on 2018/6/25. */ @Repository public interface StoreDao extends CrudRepository<Store,Integer> { //此方法通過內(nèi)連接查詢店鋪id=?中的所有商品 @Query("select distinct s from Store s inner join s.shops where s.id = ?1") List<Store> findByShopList(Integer id); }
StoreService.java
通過@Autowired注入StoreDao來(lái)實(shí)現(xiàn)方法
package com.gaolei.Service; import com.gaolei.Dao.StoreDao; import com.gaolei.Entity.Shop; import com.gaolei.Entity.Store; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.transaction.annotation.Transactional; import java.util.List; /** * Created by GaoLei on 2018/6/25. */ @Controller @Transactional public class StoreService { @Autowired private StoreDao storeDao; /** * 展示商店商品 * */ public List<Store> findByShopList(Integer id){ return storeDao.findByShopList(id); } }
StoreAction.java
實(shí)現(xiàn)具體數(shù)據(jù)操作操作
package com.gaolei.Action; import com.gaolei.Entity.Shop; import com.gaolei.Entity.Store; import com.gaolei.Service.ShopService; import com.gaolei.Service.StoreService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.util.ArrayList; import java.util.List; /** * Created by GaoLei on 2018/6/26. */ @Controller @RequestMapping("/store") public class StoreAction { @Autowired private StoreService storeService; /** * Store_shop_menu展示店鋪商品 * */ @RequestMapping("showShop") public String showShop(HttpServletResponse response ,HttpServletRequest request,Model model){ String id = request.getParameter("store_id"); //通過HQL語(yǔ)句拿到id=?的商鋪,并拿到該店鋪下所有的商品 List<Store> list = storeService.findByShopList(Integer.valueOf(id)); //返回的為一個(gè)Store集合,Store類和Shop類為一對(duì)多,Store下的shops為L(zhǎng)ist<Shop>。 List<Shop> shopList = new ArrayList<Shop>(); //循環(huán)遍歷拿到每一個(gè)shop,添加到一個(gè)新的List<Shop>中,用于將數(shù)據(jù)在前臺(tái)展示。 for (Store store:list){ System.out.println(store.getName()); for (Shop shop: store.getShops()) { System.out.println(shop.getName()); shopList.add(shop); } } model.addAttribute("list",shopList); return "admin/showShop"; } }
前臺(tái)頁(yè)面跳轉(zhuǎn)
查看的店鋪
店鋪商品
省略前端代碼,主要的是@Query("****************")中語(yǔ)句使用,配合數(shù)據(jù)庫(kù)的各種連接能實(shí)現(xiàn)復(fù)雜的操作。
感謝你能夠認(rèn)真閱讀完這篇文章,希望小編分享的“SpringBoot Data JPA關(guān)聯(lián)表查詢的示例分析”這篇文章對(duì)大家有幫助,同時(shí)也希望大家多多支持億速云,關(guān)注億速云行業(yè)資訊頻道,更多相關(guān)知識(shí)等著你來(lái)學(xué)習(xí)!
免責(zé)聲明:本站發(fā)布的內(nèi)容(圖片、視頻和文字)以原創(chuàng)、轉(zhuǎn)載和分享為主,文章觀點(diǎn)不代表本網(wǎng)站立場(chǎng),如果涉及侵權(quán)請(qǐng)聯(lián)系站長(zhǎng)郵箱:is@yisu.com進(jìn)行舉報(bào),并提供相關(guān)證據(jù),一經(jīng)查實(shí),將立刻刪除涉嫌侵權(quán)內(nèi)容。