Spring @DeleteMapping教程 · ZetCode 中文系列教程

# Spring `@DeleteMapping`教程 > 原文： [http://zetcode.com/spring/deletemapping/](http://zetcode.com/spring/deletemapping/) Spring `@DeleteMapping`教程展示了如何使用`@DeleteMapping`注解將 HTTP DELETE 請求映射到特定的處理器方法。 Spring 是用于創建企業應用的流行 Java 應用框架。 ## `@DeleteMapping` `@DeleteMapping`注解將 HTTP DELETE 請求映射到特定的處理器方法。它是一個組合的注解，用作`@RequestMapping(method = RequestMethod.DELETE)`的快捷方式。 ## Spring `@DeleteMapping`示例以下應用使用`@DeleteMapping`刪除資源。我們使用注解來設置 Spring Web 應用。 ```java pom.xml src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ ├───config │ │ │ MyWebInitializer.java │ │ │ WebConfig.java │ │ ├───controller │ │ │ MyController.java │ │ ├───model │ │ │ Post.java │ │ └───service │ │ PostService.java │ └───resources │ logback.xml └───test └───java ``` 這是項目結構。 `pom.xml` ```java <?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>com.zetcode</groupId> <artifactId>postmappingex</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> <spring-version>5.1.3.RELEASE</spring-version> </properties> <dependencies> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.1.3.RELEASE</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.8</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>3.2.2</version> </plugin> <plugin> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-maven-plugin</artifactId> <version>9.4.14.v20181114</version> </plugin> </plugins> </build> </project> ``` 在`pom.xml`文件中，我們具有項目依賴項。 `resources/logback.xml` ```java <?xml version="1.0" encoding="UTF-8"?> <configuration> <logger name="org.springframework" level="ERROR"/> <logger name="com.zetcode" level="INFO"/> <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender"> <encoder> <Pattern>%d{HH:mm:ss.SSS} %blue(%-5level) %magenta(%logger{36}) - %msg %n </Pattern> </encoder> </appender> <root> <level value="INFO" /> <appender-ref ref="consoleAppender" /> </root> </configuration> ``` `logback.xml`是 Logback 日志庫的配置文件。 `com/zetcode/config/MyWebInitializer.java` ```java package com.zetcode.config; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer; @Configuration public class MyWebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { @Override protected Class<?>[] getRootConfigClasses() { return null; } @Override protected Class<?>[] getServletConfigClasses() { return new Class[]{WebConfig.class}; } @Override protected String[] getServletMappings() { return new String[]{"/"}; } } ``` `MyWebInitializer`注冊 Spring `DispatcherServlet`，它是 Spring Web 應用的前端控制器。 ```java @Override protected Class<?>[] getServletConfigClasses() { return new Class[]{WebConfig.class}; } ``` `getServletConfigClasses()`返回 Web 配置類。 `com/zetcode/config/WebConfig.java` ```java package com.zetcode.config; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.config.annotation.EnableWebMvc; @Configuration @EnableWebMvc @ComponentScan(basePackages = {"com.zetcode"}) public class WebConfig { } ``` `WebConfig`通過`@EnableWebMvc`啟用 Spring MVC 注解，并為`com.zetcode`包配置組件掃描。 `com/zetcode/controller/MyController.java` ```java package com.zetcode.controller; import com.zetcode.model.Post; import com.zetcode.service.IPostService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.DeleteMapping; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import java.util.Set; import static org.springframework.http.ResponseEntity.ok; @Controller public class MyController { @Autowired private IPostService postService; @GetMapping(value="/posts") public ResponseEntity<Set<Post>> all() { return ok().body(postService.all()); } @DeleteMapping(value = "/posts/{id}") public ResponseEntity<Long> deletePost(@PathVariable Long id) { var isRemoved = postService.delete(id); if (!isRemoved) { return new ResponseEntity<>(HttpStatus.NOT_FOUND); } return new ResponseEntity<>(id, HttpStatus.OK); } } ``` `MyController`提供請求路徑和處理器方法之間的映射。我們有兩種映射：一種用于 GET 請求，另一種用于 DELETE 請求。 ```java @GetMapping(value="/posts") public ResponseEntity<Set<Post>> all() { return ok().body(postService.all()); } ``` 用`@GetMapping`注解的方法返回所有帖子。 ```java @DeleteMapping(value = "/posts/{id}") public ResponseEntity<Long> deletePost(@PathVariable Long id) { var isRemoved = postService.delete(id); if (!isRemoved) { return new ResponseEntity<>(HttpStatus.NOT_FOUND); } return new ResponseEntity<>(id, HttpStatus.OK); } ``` `deletePost()`帶有`@DeleteMapping`注解。該方法的工作是嘗試使用`IPostService`刪除帖子。根據結果??返回適當的`ResponseEntity`。 `com/zetcode/model/Post.java` ```java package com.zetcode.model; import java.util.Objects; public class Post { private Long id; private String content; public Post() { } public Post(Long id, String content) { this.id = id; this.content = content; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Post post = (Post) o; return Objects.equals(id, post.id) && Objects.equals(content, post.content); } @Override public int hashCode() { return Objects.hash(id, content); } } ``` 這是一個簡單的`Post` bean。它具有兩個屬性：`id`和`content`。 `com/zetcode/service/IPostService.java` ```java package com.zetcode.service; import com.zetcode.model.Post; import java.util.Set; public interface IPostService { boolean delete(Long id); Set<Post> all(); } ``` `IPostService`包含兩種簽約方法：`delete()`和`all()`。 `com/zetcode/service/PostService.java` ```java package com.zetcode.service; import com.zetcode.model.Post; import org.springframework.stereotype.Service; import java.util.HashSet; import java.util.Set; import java.util.concurrent.atomic.AtomicLong; @Service public class PostService implements IPostService { private final AtomicLong counter = new AtomicLong(); private final Set<Post> posts = new HashSet<>(Set.of(new Post(counter.incrementAndGet(), "Post one"), new Post(counter.incrementAndGet(), "Post two"), new Post(counter.incrementAndGet(), "Post three"), new Post(counter.incrementAndGet(), "Post four"))); public boolean delete(Long id) { var isRemoved = this.posts.removeIf(post -> post.getId().equals(id)); return isRemoved; } public Set<Post> all() { return this.posts; } } ``` `PostService`具有刪除帖子并返回所有帖子的方法。我們沒有實現數據庫層。相反，我們使用一個簡單的內存集合。 > **注意**：在實際應用中，我們還將實現存儲庫層。 ```java $ mvn jetty:run ``` 我們運行 Jetty 服務器。 ```java $ curl localhost:8080/posts [{"id":3,"content":"Post three"},{"id":4,"content":"Post four"}, {"id":1,"content":"Post one"},{"id":2,"content":"Post two"}] ``` 使用`curl`工具，我們可以檢索所有帖子。 ```java $ curl -i -X DELETE localhost:8080/posts/1/ HTTP/1.1 200 OK Date: Wed, 01 May 2019 12:59:07 GMT Content-Type: application/json;charset=utf-8 Transfer-Encoding: chunked Server: Jetty(9.4.14.v20181114) 1 ``` 我們刪除 ID 為 1 的信息。 ```java $ curl localhost:8080/posts [{"id":3,"content":"Post three"},{"id":4,"content":"Post four"},{"id":2,"content":"Post two"}] ``` 我們又收到了所有帖子。編號為 1 的帖子已刪除。在本教程中，我們介紹了`@DeleteMapping`注解。您可能也對這些相關教程感興趣： [Spring `@GetMapping`教程](/spring/getmapping/)， [Spring `@PostMapping`教程](/spring/postmapping/)， [Spring `@RequestMapping`教程](/spring/requestmapping/)， [Spring `@MatrixVariable`教程](/spring/matrixvariable/) 或 [Java 教程](/lang/java/)或列出[所有 Spring 教程](/all/#spring)。