這裡通過一個完整的例子展示如何通過 JPA 對單表進行增刪改查操作。

前提

• JDK 8+
• Maven 3+

表結構

例子

建立 Maven 專案

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>4.0.0</modelVersion>

    <groupId>org.lewis.demos</groupId>
    <artifactId>jpa-singletable-springboot-h2</artifactId>
    <version>1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId
 
>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 

        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </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:true

src/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);
    }

}

建立實體

src/main/java/hello/domain/Book.java

package hello.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import java.io.Serializable;

@Entity
public class Book implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue
    private Integer id;

    private String name;

    public Book() {
        super();
    }

    public Book(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;
    }

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

}

建立 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<Book> findByNameContaining(String name);

}

單元測試

編寫單元測試

src/test/java/hello/BookRepositoryTests.java

package hello;

import hello.domain.Book;
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;

    @Before
    public void init() {
        Book bookA = new Book("Spring in Action");
        Book bookB = new Book("Spring Boot in Action");
        Book bookC = new Book("Spring Data in Action");
        bookRepository.save(Arrays.asList(bookA, bookB, bookC));
    }

    @After
    public void deleteAll() {
        bookRepository.deleteAll();
    }

    @Test
    public void findAll() {
        assertThat(bookRepository.findAll()).hasSize(3);
    }

    @Test
    public void findByName() {
        assertThat(bookRepository.findByName("Spring in Action")).isNotNull();
        assertThat(bookRepository.findByName("Spring in")).isNull();
    }

    @Test
    public void findByNameContaining() {
        assertThat(bookRepository.findByNameContaining("Spring")).hasSize(3);
    }

    @Test
    public void marge() {
        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 delete() {
        Book book = bookRepository.findByName("Spring in Action");
        assertThat(book).isNotNull();

        bookRepository.delete(book);

        assertThat(bookRepository.findAll()).hasSize(2);
        assertThat(bookRepository.findByName("Spring in Action")).isNull();
    }

}

執行測試用例

mvn clean test

資源