Spring Data JPA 實現多表關聯查詢

Spring Data JPA 實現多表關聯查詢

多表查詢在spring data jpa中有兩種實現方式，第一種是利用hibernate的級聯查詢來實現，第二種是創建一個結果集的接口來接收連表查詢后的結果，這里介紹第二種方式。

一、一對一映射

實體 UserInfo ：用戶。

實體 Address：家庭住址。

這里通過外鍵的方式(一個實體通過外鍵關聯到另一個實體的主鍵)來實現一對一關聯。

實體類

1、實體類 UserInfo.java

package com.johnfnash.learn.domain;
import java.io.Serializable;
import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
 import javax.persistence.Table;
@Entity
 @Table(name="tb_user")
 public class UserInfo implements Serializable {
 private static final long serialVersionUID = 8283950216116626180L;
@Id
 @GeneratedValue(strategy=GenerationType.IDENTITY)
 private Long userId;
 private String name;
 private int age;
 private String sex;
 private String email;
// 與 Address 的關聯 
 private Long addressId;
public UserInfo() {
 super();
 }
public UserInfo(String name, int age, String sex, String email, Long addressId) {
 super();
 this.name = name;
 this.age = age;
 this.sex = sex;
 this.email = email;
 this.addressId = addressId;
 }
// getter, setter
@Override
 public String toString() {
 return String.format("UserInfo [userId=%d, name=%s, age=%s, sex=%s, email=%s]", userId, name, age, sex, email);
 }
}
    
    
    
            

   
   
   
           

2. 實體類 Address.java

package com.johnfnash.learn.domain;
import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
 import javax.persistence.Table;
@Entity
 @Table(name = "tb_address")
 public class Address {
@Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)
 private Long addressId;
 private String areaCode;
 private String country;
 private String province;
 private String city;
 private String area;
 private String detailAddress;
public Address() {
 super();
 }
public Address(String areaCode, String country, String province, String city, String area,
 String detailAddress) {
 super();
 this.areaCode = areaCode;
 this.country = country;
 this.province = province;
 this.city = city;
 this.area = area;
 this.detailAddress = detailAddress;
 }
// getter, setter
@Override
 public String toString() {
 return "Address [addressId=" + addressId + ", areaCode=" + areaCode + ", country=" + country + ", province="
 + province + ", city=" + city + ", area=" + area + ", detailAddress=" + detailAddress + "]";
 }
}

    
    
    
            

   
   
   
           

Dao 層

1、UserInfoRepository.java

package com.johnfnash.learn.repository;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
import com.johnfnash.learn.domain.UserInfo;
 import com.johnfnash.learn.domain.ViewInfo;
public interface UserInfoRepository extends JpaRepository<UserInfo, Long> {
@Query(value = "SELECT new com.johnfnash.learn.domain.ViewInfo(u, a) FROM UserInfo u, Address a WHERE u.addressId = a.addressId")
 public List<ViewInfo> findViewInfo();
}
    
    
    
            

   
   
   
           

注：這里的 ViewInfo 類用來一個用來接收多表查詢結果集的類（使用 new + 完整類名構造函數）
代碼如下：

package com.johnfnash.learn.domain;
import java.io.Serializable;
public class ViewInfo implements Serializable {
private static final long serialVersionUID = -6347911007178390219L;
private UserInfo userInfo;
 private Address address;
public ViewInfo() {
}
public ViewInfo(UserInfo userInfo) {
 Address address = new Address();
 this.userInfo = userInfo;
 this.address = address;
 }
public ViewInfo(Address address) {
 UserInfo userInfo = new UserInfo();
 this.userInfo = userInfo;
 this.address = address;
 }
public ViewInfo(UserInfo userInfo, Address address) {
 this.userInfo = userInfo;
 this.address = address;
 }
// getter, setter
}
    
    
    
            

   
   
   
           

2. AddressRepository.java

package com.johnfnash.learn.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import com.johnfnash.learn.domain.Address;
public interface AddressRepository extends JpaRepository<Address, Long> {
}

    
    
    
            

   
   
   
           

測試代碼

package com.johnfnash.learn;
import java.util.List;
import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.test.context.junit4.SpringRunner;
import com.johnfnash.learn.domain.Address;
 import com.johnfnash.learn.domain.UserInfo;
 import com.johnfnash.learn.domain.ViewInfo;
 import com.johnfnash.learn.repository.AddressRepository;
 import com.johnfnash.learn.repository.UserInfoRepository;
@RunWith(SpringRunner.class)
 @SpringBootTest
 public class UserInfoRepositoryTests {
@Autowired
 private UserInfoRepository userInfoRepository;
@Autowired
 private AddressRepository addressRepository;
@Before
 public void init() {
 Address addr1 = new Address("027","CN","HuBei", "WuHan","WuChang", "123 street");
 Address addr2 = new Address("023","CN","ChongQing", "ChongQing","YuBei", "123 road");
 addressRepository.save(addr1);
 addressRepository.save(addr2);
    UserInfo user1 = new UserInfo(<span class="hljs-string">"ZS"</span>, <span class="hljs-number">21</span>,<span class="hljs-string">"Male"</span>,<span class="hljs-string">"[e-mail]"</span>, addr1<span class="hljs-preprocessor">.getAddressId</span>())<span class="hljs-comment">;</span>
    UserInfo user2 = new UserInfo(<span class="hljs-string">"Ww"</span>, <span class="hljs-number">25</span>,<span class="hljs-string">"Male"</span>,<span class="hljs-string">"[e-mail]"</span>, addr2<span class="hljs-preprocessor">.getAddressId</span>())<span class="hljs-comment">;</span>
    userInfoRepository<span class="hljs-preprocessor">.save</span>(user1)<span class="hljs-comment">;</span>
    userInfoRepository<span class="hljs-preprocessor">.save</span>(user2)<span class="hljs-comment">;</span>
}

@After
 public void deleteAll() {
 userInfoRepository.deleteAll();
addressRepository<span class="hljs-preprocessor">.deleteAll</span>()<span class="hljs-comment">;</span>

}
@Test
 public void testQuery() {
 List<ViewInfo> viewInfos = userInfoRepository.findViewInfo();
 for (ViewInfo viewInfo : viewInfos) {
 System.out.println(viewInfo.getUserInfo());
 System.out.println(viewInfo.getAddress());
 }
 }
}
    
    
    
            

   
   
   
           

查詢相關的 sql 如下：

Hibernate: select userinfo0_.user_id as col_0_0_, address1_.address_id as col_1_0_ from tb_user userinfo0_ cross join tb_address address1_ where userinfo0_.address_id=address1_.address_id Hibernate: select userinfo0_.user_id as user_id1_4_0_, userinfo0_.address_id as address_2_4_0_, userinfo0_.age as age3_4_0_, userinfo0_.email as email4_4_0_, userinfo0_.name as name5_4_0_, userinfo0_.sex as sex6_4_0_ from tb_user userinfo0_ where userinfo0_.user_id=? Hibernate: select address0_.address_id as address_1_3_0_, address0_.area as area2_3_0_, address0_.area_code as area_cod3_3_0_, address0_.city as city4_3_0_, address0_.country as country5_3_0_, address0_.detail_address as detail_a6_3_0_, address0_.province as province7_3_0_ from tb_address address0_ where address0_.address_id=? Hibernate: select userinfo0_.user_id as user_id1_4_0_, userinfo0_.address_id as address_2_4_0_, userinfo0_.age as age3_4_0_, userinfo0_.email as email4_4_0_, userinfo0_.name as name5_4_0_, userinfo0_.sex as sex6_4_0_ from tb_user userinfo0_ where userinfo0_.user_id=? Hibernate: select address0_.address_id as address_1_3_0_, address0_.area as area2_3_0_, address0_.area_code as area_cod3_3_0_, address0_.city as city4_3_0_, address0_.country as country5_3_0_, address0_.detail_address as detail_a6_3_0_, address0_.province as province7_3_0_ from tb_address address0_ where address0_.address_id=? Hibernate: select userinfo0_.user_id as user_id1_4_, userinfo0_.address_id as address_2_4_, userinfo0_.age as age3_4_, userinfo0_.email as email4_4_, userinfo0_.name as name5_4_, userinfo0_.sex as sex6_4_ from tb_user userinfo0_ Hibernate: select address0_.address_id as address_1_3_, address0_.area as area2_3_, address0_.area_code as area_cod3_3_, address0_.city as city4_3_, address0_.country as country5_3_, address0_.detail_address as detail_a6_3_, address0_.province as province7_3_ from tb_address address0_
    
    
    
            

   
   
   
           

查詢結果如下：

UserInfo [userId=1, name=ZS, age=21, sex=Male, email=[e-mail]]
Address [addressId=1, areaCode=027, country=CN, province=HuBei, city=WuHan, area=WuChang, detailAddress=123 street]
UserInfo [userId=2, name=Ww, age=25, sex=Male, email=[e-mail]]
Address [addressId=2, areaCode=023, country=CN, province=ChongQing, city=ChongQing, area=YuBei, detailAddress=123 road]
    
    
    
            

   
   
   
           

二、多對多映射

實體 Author ：作者。

實體 Book ：書籍

這里通過關聯表的方式來實現多對多關聯。

實體類

實體類：Author.java

package com.johnfnash.learn.domain;
import java.io.Serializable;
import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
@Entity
 public class Author implements Serializable {
private static final long serialVersionUID = 1227555837798655046L;
@Id
 @GeneratedValue
 private Integer id;
<span class="hljs-keyword">private</span> String name;

public Author() {
 super();
 }
public Author(String name) {
 super();
 this.name = name;
 }
// getter, setter
@Override
 public String toString() {
 return String.format("Author [id=%s, name=%s]", id, name);
 }
}
    
    
    
            

   
   
   
           

Book.java 實體類

package com.johnfnash.learn.domain;
import java.io.Serializable;
import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
@Entity
 public class Book implements Serializable {
private static final long serialVersionUID = -2470510857424220408L;
@Id
 @GeneratedValue
 private Integer id;
<span class="hljs-keyword">private</span> String name;

<span class="hljs-keyword">public</span> <span class="hljs-title">Book</span>() {
    <span class="hljs-keyword">super</span>();
}

<span class="hljs-keyword">public</span> <span class="hljs-title">Book</span>(String name) {
    <span class="hljs-keyword">super</span>();
    <span class="hljs-keyword">this</span>.name = name;
}

//getter, setter
@Override
 public String toString() {
 return String.format("Book [id=%s, name=%s]", id, name);
 }
}
    
    
    
            

   
   
   
           

實體類BookAuthor.java

package com.johnfnash.learn.domain;
import javax.persistence.Entity;
 import javax.persistence.Id;
 import javax.persistence.IdClass;
 import javax.persistence.Table;
@Entity
 @IdClass(BookAuthorPK.class)
 @Table(name = "book_author")
 public class BookAuthor {
@Id
 private Integer bookId;
@Id
 private Integer authorId;
public BookAuthor() {
 super();
 }
public BookAuthor(Integer bookId, Integer authorId) {
 super();
 this.bookId = bookId;
 this.authorId = authorId;
 }
// getter, setter
}
    
    
    
            

   
   
   
           

注：這里使用 @IdClass 注解指定一個聯合主鍵類來映射實體類的多個屬性。這個聯合主鍵類的代碼如下：

package com.johnfnash.learn.domain;
import java.io.Serializable;
public class BookAuthorPK implements Serializable {
private static final long serialVersionUID = -1158141803682305656L;
private Integer bookId;
private Integer authorId;
public Integer getBookId() {
 return bookId;
 }
public void setBookId(Integer bookId) {
 this.bookId = bookId;
 }
public Integer getAuthorId() {
 return authorId;
 }
public void setAuthorId(Integer authorId) {
 this.authorId = authorId;
 }
}
    
    
    
            

   
   
   
           

Dao 層

BookRepository.java

package com.johnfnash.learn.repository;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
import com.johnfnash.learn.domain.Book;
public interface BookRepository extends JpaRepository<Book, Integer> {
@Query(nativeQuery = true, value = "SELECT b.id, b.name, GROUP_CONCAT(a.name) as authorName from book b, author a, book_author ba"
 + " where b.id = ba.book_id and a.id = ba.author_id and b.name like ?1 group by b.id, b.name")
 List<Object[]> findByNameContaining(String name);
}
    
    
    
            

   
   
   
           

注：
1）這里使用 nativeQuery = true 指定使用原生 SQL 進行查詢（個人覺得復雜的查詢使用原生SQL更好
2）這里使用了 mysql 的內置函數 GROUP_CONCAT 進行行轉列, HQL 無法直接識別。可能會出現 Caused by: org.hibernate.QueryException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 的錯誤

JpaRepository.java

package com.johnfnash.learn.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import com.johnfnash.learn.domain.Author;
public interface AuthorRepository extends JpaRepository<Author, Integer> {
}
    
    
    
            

   
   
   
           

BookAuthorRepository.java

package com.johnfnash.learn.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import com.johnfnash.learn.domain.BookAuthor;
public interface BookAuthorRepository extends JpaRepository<BookAuthor, Integer> {
}
    
    
    
            

   
   
   
           

測試代碼

package com.johnfnash.learn;
import static org.junit.Assert.assertEquals;
import java.util.List;
import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.test.context.junit4.SpringRunner;
import com.johnfnash.learn.domain.Author;
 import com.johnfnash.learn.domain.Book;
 import com.johnfnash.learn.domain.BookAuthor;
 import com.johnfnash.learn.repository.AuthorRepository;
 import com.johnfnash.learn.repository.BookAuthorRepository;
 import com.johnfnash.learn.repository.BookRepository;
@RunWith(SpringRunner.class)
 @SpringBootTest
 public class BookRepositoryTests {
@Autowired
 private BookRepository bookRepository;
@Autowired
 private AuthorRepository authorRepository;
@Autowired
 private BookAuthorRepository bookAuthorRepository;
@Before
 public void init() {
 Author lewis = new Author("Lewis");
 Author mark = new Author("Mark");
 Author peter = new Author("Peter");
 authorRepository.save(lewis);
 authorRepository.save(mark);
 authorRepository.save(peter);
  Book spring = new Book(<span class="hljs-string">"Spring in Action"</span>)<span class="hljs-comment">;</span>
  Book springboot = new Book(<span class="hljs-string">"Spring Boot in Action"</span>)<span class="hljs-comment">;</span>
  bookRepository<span class="hljs-preprocessor">.save</span>(spring)<span class="hljs-comment">;</span>
  bookRepository<span class="hljs-preprocessor">.save</span>(springboot)<span class="hljs-comment">;</span>

  bookAuthorRepository<span class="hljs-preprocessor">.save</span>(new BookAuthor(spring<span class="hljs-preprocessor">.getId</span>(), lewis<span class="hljs-preprocessor">.getId</span>()))<span class="hljs-comment">;</span>
  bookAuthorRepository<span class="hljs-preprocessor">.save</span>(new BookAuthor(spring<span class="hljs-preprocessor">.getId</span>(), mark<span class="hljs-preprocessor">.getId</span>()))<span class="hljs-comment">;</span>
  bookAuthorRepository<span class="hljs-preprocessor">.save</span>(new BookAuthor(springboot<span class="hljs-preprocessor">.getId</span>(), mark<span class="hljs-preprocessor">.getId</span>()))<span class="hljs-comment">;</span>
  bookAuthorRepository<span class="hljs-preprocessor">.save</span>(new BookAuthor(springboot<span class="hljs-preprocessor">.getId</span>(), peter<span class="hljs-preprocessor">.getId</span>()))<span class="hljs-comment">;</span>

}
@After
 public void deleteAll() {
 bookAuthorRepository.deleteAll();
 bookRepository.deleteAll();
 authorRepository.deleteAll();
 }
@Test
 public void findAll() {
 assertEquals(bookRepository.findAll().size(), 2);
 assertEquals(authorRepository.findAll().size(), 3);
List&lt;Object[]&gt; books = bookRepository<span class="hljs-preprocessor">.findByNameContaining</span>(<span class="hljs-string">"Spring%"</span>)<span class="hljs-comment">;</span>
for (Object[] book : books) {
  for (Object object : book) {
    System<span class="hljs-preprocessor">.out</span><span class="hljs-preprocessor">.print</span>(object + <span class="hljs-string">", "</span>)<span class="hljs-comment">;</span>
  }
  System<span class="hljs-preprocessor">.out</span><span class="hljs-preprocessor">.println</span>()<span class="hljs-comment">;</span>
}

}
}
    
    
    
            

   
   
   
           

執行 findAll 方法后，查詢的相關 SQL 如下：

Hibernate: SELECT b.id, b.name, GROUP_CONCAT(a.name) as authorName from book b, author a, book_author ba where b.id = ba.book_id and a.id = ba.author_id and b.name like ? group by b.id, b.name
    
    
    
            

   
   
   
           

輸出的結果如下：

3652, Spring in Action, Lewis,Mark, 
3653, Spring Boot in Action, Mark,Peter, 
    
    
    
            

   
   
   
           

參考

(1) Spring Data JPA 實現多表關聯查詢

(2) springboot(五): spring data jpa的使用

https://blog.csdn.net/johnf_nash/article/details/80587204