Spring Data JPA 系列 —— 两张表（多对多关联）
这里通过一个完整的例子展示如何通过 JPA 对两张表（多对多关联）进行增删改查操作。
前提
- JDK 8+
- Maven 3+
表结构
例子
创建 Maven 项目
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0modelVersion>
<groupId>org.lewis.demosgroupId>
<artifactId>jpa-manytomany-springboot-h2artifactId>
<version>1.0version>
<parent>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-parentartifactId>
<version>1.5.2.RELEASEversion>
<relativePath/>
parent>
<properties>
<project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8project.reporting.outputEncoding>
<java.version>1.8java.version>
properties>
<dependencies>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-data-jpaartifactId>
dependency>
<dependency>
<groupId>com.h2databasegroupId>
<artifactId>h2artifactId>
<scope>runtimescope>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-maven-pluginartifactId>
plugin>
plugins>
build>
project>src/main/resources/application.properties
## DATASOURCE Settings
#spring.datasource.driver-class-name:org.h2.Driver
#spring.datasource.password:demo
#spring.datasource.url:jdbc:h2:tcp://127.0.0.1/~/jpa-h2
#spring.datasource.username:demo
## JPA Settings
spring.jpa.generate-ddl:true
spring.jpa.hibernate.ddl-auto:update
#spring.jpa.hibernate.dialect:org.hibernate.dialect.H2Dialect
spring.jpa.properties.hibernate.format_sql:false
spring.jpa.show-sql:truesrc/main/java/hello/Application.java
package hello;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}创建实体
src/main/java/hello/domain/Book.java
package hello.domain;
import javax.persistence.*;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
@Entity
public class Book implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private Integer id;
private String name;
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "BOOK_AUTHOR", joinColumns = {
@JoinColumn(name = "BOOK_ID", referencedColumnName = "ID")}, inverseJoinColumns = {
@JoinColumn(name = "AUTHOR_ID", referencedColumnName = "ID")})
private Set authors;
public Book() {
super();
}
public Book(String name) {
super();
this.name = name;
this.authors = new HashSet<>();
}
public Book(String name, Set authors) {
super();
this.name = name;
this.authors = authors;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set getAuthors() {
return authors;
}
public void setAuthors(Set authors) {
this.authors = authors;
}
@Override
public String toString() {
return String.format("Book [id=%s, name=%s, authors=%s]", id, name, authors);
}
} src/main/java/hello/domain/Author.java
package hello.domain;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import java.io.Serializable;
import java.util.Set;
@Entity
public class Author implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private Integer id;
private String name;
@ManyToMany(mappedBy = "authors")
private Set books;
public Author() {
super();
}
public Author(String name) {
super();
this.name = name;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set getBooks() {
return books;
}
public void setBooks(Set books) {
this.books = books;
}
@Override
public String toString() {
return String.format("Author [id=%s, name=%s, books=%s]", id, name, books);
}
} 创建 Repository
src/main/java/hello/repository/BookRepository.java
package hello.repository;
import hello.domain.Book;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.List;
public interface BookRepository extends JpaRepository<Book, Integer> {
Book findByName(String name);
List findByNameContaining(String name);
} src/main/java/hello/repository/AuthorRepository.java
package hello.repository;
import hello.domain.Author;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.List;
public interface AuthorRepository extends JpaRepository<Author, Integer> {
Author findByName(String name);
List findByNameContaining(String name);
} 单元测试
编写单元测试
src/test/java/hello/BookRepositoryTests.java
package hello;
import hello.domain.Author;
import hello.domain.Book;
import hello.repository.AuthorRepository;
import hello.repository.BookRepository;
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.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.Arrays;
import static org.assertj.core.api.Assertions.assertThat;
@RunWith(SpringRunner.class)
@DataJpaTest
public class BookRepositoryTests {
@Autowired
private BookRepository bookRepository;
@Autowired
private AuthorRepository authorRepository;
@Before
public void init() {
Author lewis = new Author("Lewis");
Author mark = new Author("Mark");
Author peter = new Author("Peter");
Book spring = new Book("Spring in Action");
spring.getAuthors().addAll(Arrays.asList(lewis, mark));
Book springboot = new Book("Spring Boot in Action");
springboot.getAuthors().addAll(Arrays.asList(lewis, peter));
bookRepository.save(Arrays.asList(spring, springboot));
}
@After
public void deleteAll() {
// 删除所有书籍，级联删除关联的作者，但是没有与书籍关联的作者不会被删掉
bookRepository.deleteAll();
// 删除所有作者，只能删除没有与书籍关联的作者，与书籍有关联的作者无法被删除
authorRepository.deleteAll();
}
@Test
public void findAll() {
assertThat(bookRepository.findAll()).hasSize(2);
assertThat(authorRepository.findAll()).hasSize(3);
}
@Test
public void findByName() {
assertThat(bookRepository.findByName("Spring in Action")).isNotNull();
assertThat(authorRepository.findByName("Lewis")).isNotNull();
}
@Test
public void findByNameContaining() {
assertThat(bookRepository.findByNameContaining("Spring")).hasSize(2);
assertThat(authorRepository.findByNameContaining("e")).hasSize(2);
}
@Test
public void margeBook() {
Book book = bookRepository.findByName("Spring in Action");
assertThat(book).isNotNull();
book.setName("Spring in Action (4th Edition)");
bookRepository.save(book);
assertThat(bookRepository.findByName("Spring in Action")).isNull();
assertThat(bookRepository.findByName("Spring in Action (4th Edition)")).isNotNull();
}
@Test
public void deleteBook() {
Book book = bookRepository.findByName("Spring Boot in Action");
assertThat(book).isNotNull();
bookRepository.delete(book);
assertThat(bookRepository.findAll()).hasSize(1);
assertThat(bookRepository.findByName("Spring Boot in Action")).isNull();
assertThat(authorRepository.findAll()).hasSize(2);
assertThat(authorRepository.findByName("Peter")).isNull();
}
@Test
public void plusAuthor() {
Book book = bookRepository.findByName("Spring in Action");
assertThat(book).isNotNull();
Author author = authorRepository.findByName("Jacob");
assertThat(author).isNull();
book.getAuthors().add(new Author("Jacob"));
bookRepository.save(book);
assertThat(bookRepository.findByName("Spring in Action").getAuthors()).hasSize(3);
assertThat(authorRepository.findAll()).hasSize(4);
assertThat(authorRepository.findByName("Jacob")).isNotNull();
}
@Test
public void clearAuthor() {
Book book = bookRepository.findByName("Spring in Action");
assertThat(book).isNotNull();
book.getAuthors().clear();
bookRepository.save(book);
assertThat(bookRepository.findAll()).hasSize(2);
assertThat(bookRepository.findByName("Spring in Action").getAuthors()).isEmpty();
assertThat(authorRepository.findAll()).hasSize(3);
}
@Test
public void removeAuthor() {
Book book = bookRepository.findByName("Spring Boot in Action");
assertThat(book).isNotNull();
Author author = authorRepository.findByName("Peter");
assertThat(author).isNotNull();
book.getAuthors().remove(author);
bookRepository.save(book);
assertThat(bookRepository.findAll()).hasSize(2);
assertThat(bookRepository.findByName("Spring Boot in Action").getAuthors()).hasSize(1);
assertThat(authorRepository.findAll()).hasSize(3);
assertThat(authorRepository.findByName("Peter")).isNotNull();
}
@Test
public void removeAllautors() {
Book book = bookRepository.findByName("Spring in Action");
assertThat(book).isNotNull();
book.getAuthors().removeAll(book.getAuthors());
bookRepository.save(book);
assertThat(bookRepository.findAll()).hasSize(2);
assertThat(bookRepository.findByName("Spring in Action").getAuthors()).isEmpty();
assertThat(authorRepository.findAll()).hasSize(3);
}
@Test
public void deleteAuthor() {
Author author = authorRepository.findByName("Peter");
assertThat(author).isNotNull();
authorRepository.delete(author);
assertThat(bookRepository.findAll()).hasSize(2);
assertThat(bookRepository.findByName("Spring in Action").getAuthors()).hasSize(2);
assertThat(bookRepository.findByName("Spring Boot in Action").getAuthors()).hasSize(2);
assertThat(authorRepository.findAll()).hasSize(3);
assertThat(authorRepository.findByName("Peter")).isNotNull();
}
@Test
public void deleteAllAuthors() {
authorRepository.deleteAll();
assertThat(bookRepository.findAll()).hasSize(2);
assertThat(bookRepository.findByName("Spring in Action").getAuthors()).hasSize(2);
assertThat(bookRepository.findByName("Spring Boot in Action").getAuthors()).hasSize(2);
assertThat(authorRepository.findAll()).hasSize(3);
}
}执行测试用例
mvn clean test资源
- 源码地址： https://github.com/lewis007/jpa-manytomany-springboot-h2.git
- 博客地址： http://blog.csdn.net/lewis_007/article/details/53006602
- 参考网址： http://www.cnblogs.com/luxh/archive/2012/05/30/2527123.html