使用 JPA 配置的 Spring REST CRUD 示例 · HowToDoInJava 中文系列教程

# 使用 JPA 配置的 Spring REST CRUD 示例 > 原文： [https://howtodoinjava.com/spring-restful/spring-rest-crud-jpa-example/](https://howtodoinjava.com/spring-restful/spring-rest-crud-jpa-example/) 学习**使用 **Spring REST 和 JPA** 配置（以 H2 数据库为后端）**创建 [REST API](https://restfulapi.net) 以进行分类操作**，而无需 [Spring boot](https://howtodoinjava.com/spring-boot-tutorials/)** 自动配置功能。 ## 1\. Maven 依赖在此示例中，我们使用以下模块及其依赖项。 * `spring-webmvc` – 用于处理请求 * `spring-data-jpa` – 为接口提供了支持针对后端数据存储读取，更新，删除和创建记录的方法。 * `persistence-api` – JPA 规范 * `javax.persistence` -JPA 实现 * **Hibernate 实体管理器** – 作为实体供体商 * **Jackson** – 用于 JSON 支持 * **H2** – 作为数据库 `pom.xml` ```java <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>com.howtodoinjava.rest</groupId> <artifactId>SpringRestExample</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>SpringRestExample</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <spring.version>5.1.6.RELEASE</spring.version> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> </properties> <dependencies>  <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency>  <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-jpa</artifactId> <version>2.1.6.RELEASE</version> </dependency>  <dependency> <groupId>javax.persistence</groupId> <artifactId>persistence-api</artifactId> <version>1.0.2</version> </dependency>  <dependency> <groupId>org.eclipse.persistence</groupId> <artifactId>javax.persistence</artifactId> <version>2.1.0</version> </dependency>  <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>5.4.2.Final</version> </dependency>  <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <version>1.4.199</version> </dependency>  <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.8</version> </dependency> </dependencies> </project> ``` ## 2\. `DispatcherServlet`声明我们已经在`web.xml`文件中配置了[`DispatcherServlet`](https://howtodoinjava.com/spring5/webmvc/spring-dispatcherservlet-tutorial/)，该文件会将传入的请求路由到适当的控制器方法。 `web.xml` ```java <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>Employee Management REST APIs</display-name> <servlet> <servlet-name>rest</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>rest</servlet-name> <url-pattern>/api/rest/*</url-pattern> </servlet-mapping> </web-app> ``` ## 3\. Spring 和 JPA 配置在`rest-servlet.xml`文件中，我们已经配置了[组件扫描和基于注解的配置](https://howtodoinjava.com/spring5/core/spring-bean-container-java-configuration-example/)支持。随之，我们配置了实体管理器和数据源配置。 `rest-servlet.xml` ```java <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <context:component-scan base-package="com.howtodoinjava.demo" /> <mvc:annotation-driven /> <jpa:repositories base-package="com.howtodoinjava.demo.repository" entity-manager-factory-ref="emf"/> <bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="packagesToScan" value="com.howtodoinjava.demo.model" /> <property name="dataSource" ref="dataSource" /> <property name="jpaProperties"> <props> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.hbm2ddl.auto">create</prop> <prop key="hibernate.dialect">org.hibernate.dialect.H2Dialect</prop> </props> </property> <property name="persistenceProvider"> <bean class="org.hibernate.jpa.HibernatePersistenceProvider"></bean> </property> </bean> <bean class="org.springframework.jdbc.datasource.SimpleDriverDataSource" id="dataSource"> <property name="driverClass" value="org.h2.Driver" /> <property name="url" value="jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;TRACE_LEVEL_SYSTEM_OUT=2" /> </bean> <tx:annotation-driven transaction-manager="transactionManager" /> <bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager"> <property name="dataSource" ref="dataSource" /> </bean> </beans> ``` ## 4\. 实体类我们只有一个实体类，它将保留在数据库中，并将作为 REST API 的响应返回。 * `@Entity` – JPA 注解，以使对象准备好存储在基于 JPA 的数据存储区中。 * `@Table` – 数据存储中将存储此实体的表的名称。 > 阅读更多： [JPA 2 持久性注解](https://howtodoinjava.com/hibernate/hibernate-jpa-2-persistence-annotations-tutorial/) `Employee.java` ```java 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 = "tbl_employee") public class Employee implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String firstName; private String lastName; private String email; public Employee() { } //Getters and setters @Override public String toString() { return "EmployeeVO [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]"; } } ``` ## 5\. 存储库我们已将`JpaRepository`实现创建为`EmployeeRepository`，它提供了用于对员工实体执行搜索，获取，更新和删除操作的所有默认操作。 `EmployeeRepository.java` ```java import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.stereotype.Repository; import com.howtodoinjava.demo.model.Employee; @Repository public interface EmployeeRepository extends JpaRepository<Employee, Long> { } ``` ## 6\. REST 控制器 REST 控制器定义了可以调用以对员工资源执行操作的所有 CRUD 方法。在给定的控制器中，`@RestController`注解指示方法返回的数据将直接写入响应主体中，而不呈现模板。其他注解（`@GetMapping`，`@PostMapping`，`@PutMapping`和`@DeleteMapping`）将 HTTP 请求映射到相应的方法。 `EmployeeRESTController.java` ```java import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.MediaType; import org.springframework.web.bind.annotation.DeleteMapping; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.PutMapping; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import com.howtodoinjava.demo.model.Employee; import com.howtodoinjava.demo.repository.EmployeeRepository; @RestController @RequestMapping(value = "/employee-management", produces = { MediaType.APPLICATION_JSON_VALUE }) public class EmployeeRESTController { @Autowired private EmployeeRepository repository; public EmployeeRepository getRepository() { return repository; } public void setRepository(EmployeeRepository repository) { this.repository = repository; } @GetMapping(value = "/employees") public List<Employee> getAllEmployees() { return repository.findAll(); } @PostMapping("/employees") Employee createOrSaveEmployee(@RequestBody Employee newEmployee) { return repository.save(newEmployee); } @GetMapping("/employees/{id}") Employee getEmployeeById(@PathVariable Long id) { return repository.findById(id).get(); } @PutMapping("/employees/{id}") Employee updateEmployee(@RequestBody Employee newEmployee, @PathVariable Long id) { return repository.findById(id).map(employee -> { employee.setFirstName(newEmployee.getFirstName()); employee.setLastName(newEmployee.getLastName()); employee.setEmail(newEmployee.getEmail()); return repository.save(employee); }).orElseGet(() -> { newEmployee.setId(id); return repository.save(newEmployee); }); } @DeleteMapping("/employees/{id}") void deleteEmployee(@PathVariable Long id) { repository.deleteById(id); } } ``` ## 7\. Spring REST CRUD 操作演示让我们测试一下 API 操作，以验证它们是否有效。 #### 7.1. 创建员工 `API Request` ```java HTTP POST : http://localhost:8080/SpringRestExample/api/rest/employee-management/employees { "firstName": "lokesh", "lastName": "gupta", "email": "abc@gmail.com" } ``` `API Response` ```java HTTP Response code : 200 { "id": 1, "firstName": "lokesh", "lastName": "gupta", "email": "abc@gmail.com" } ``` 创建更多的员工进行测试。 #### 7.2. 获取员工集合 `API Request` ```java HTTP GET : http://localhost:8080/SpringRestExample/api/rest/employee-management/employees ``` `API Response` ```java HTTP Response code : 200 [ { "id": 1, "firstName": "lokesh", "lastName": "gupta", "email": "abc@gmail.com" }, { "id": 2, "firstName": "Amit", "lastName": "Sharma", "email": "xyz@gmail.com" } ] ``` #### 7.3. 按编号获取员工 `API Request` ```java HTTP GET : http://localhost:8080/SpringRestExample/api/rest/employee-management/employees/1 ``` `API Response` ```java HTTP Response code : 200 { "id": 1, "firstName": "lokesh", "lastName": "gupta", "email": "abc@gmail.com" } ``` #### 7.4. 更新员工 `API Request` ```java HTTP PUT : http://localhost:8080/SpringRestExample/api/rest/employee-management/employees/1 { "firstName": "Lucky", "lastName": "Gupta", "email": "abc@gmail.com" } ``` `API Response` ```java HTTP Response code : 200 { "id": 1, "firstName": "Lucky", "lastName": "Gupta", "email": "abc@gmail.com" } ``` #### 7.5. 删除员工 `API Request` ```java HTTP DELETE : http://localhost:8080/SpringRestExample/api/rest/employee-management/employees/1 ``` `API Response` ```java HTTP Response code : 200 ``` 学习愉快！ [下载源码](https://howtodoinjava.com/wp-content/downloads/SpringRestExample.zip)