Spring @PostMapping教程 · ZetCode 中文系列教程

# Spring `@PostMapping`教程 > 原文： [http://zetcode.com/spring/postmapping/](http://zetcode.com/spring/postmapping/) Spring `@PostMapping`教程显示了如何使用`@PostMapping`注解将 HTTP POST 请求映射到特定的处理器方法。 Spring 是用于创建企业应用的流行 Java 应用框架。 ## `@PostMapping` `@PostMapping`注解将 HTTP POST 请求映射到特定的处理器方法。它是一个组合的注解，用作`@RequestMapping(method = RequestMethod.POST)`的快捷方式。 ## Spring `@PostMapping`示例以下应用使用`@PostMapping`创建新资源。在此示例中，我们使用注解来设置 Spring Web 应用。 ```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 ``` 这是项目结构。 `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，我们具有项目依赖项。 `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 日志库的配置文件。 `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`注册 Spring `DispatcherServlet`，它是 Spring Web 应用的前端控制器。 ```java @Override protected Class<?>[] getServletConfigClasses() { return new Class[]{WebConfig.class}; } ``` `getServletConfigClasses()`返回 Web 配置类。 `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`通过`@EnableWebMvc`启用 Spring MVC 注解，并为`com.zetcode`包配置组件扫描。 `com/zetcode/controller/MyController.java` ```java package com.zetcode.controller; import com.zetcode.model.Post; import com.zetcode.service.PostService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.ResponseEntity; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.util.UriComponents; import org.springframework.web.util.UriComponentsBuilder; import javax.servlet.http.HttpServletRequest; import java.util.Set; import static org.springframework.http.ResponseEntity.ok; @Controller public class MyController { @Autowired private PostService postService; @GetMapping(value="/posts") public ResponseEntity<Set<Post>> all() { return ok().body(postService.all()); } @PostMapping(value = "/posts") public ResponseEntity<Post> createPost(HttpServletRequest request, UriComponentsBuilder uriComponentsBuilder) { var content = request.getParameter("content"); var post = new Post(); post.setContent(content); post = postService.save(post); UriComponents uriComponents = uriComponentsBuilder.path("/posts/{id}").buildAndExpand(post.getId()); var location = uriComponents.toUri(); return ResponseEntity.created(location).build(); } } ``` `MyController`提供请求路径和处理器方法之间的映射。 > **注意**：这是一个很好的做法，在响应头返回新创建资源的位置。 ```java @PostMapping(value = "/posts") public ResponseEntity<Post> createPost(HttpServletRequest request, UriComponentsBuilder uriComponentsBuilder) { ``` `@PostMapping`将`createPost()`方法映射到`/posts` URL。 ```java var content = request.getParameter("content"); ``` 我们获得 POST 请求的`content`参数。 ```java var post = new Post(); post.setContent(content); post = postService.save(post); ``` 创建一个新帖子，并将其保存在一个帖子服务中。 ```java UriComponents uriComponents = uriComponentsBuilder.path("/posts/{id}").buildAndExpand(post.getId()); var location = uriComponents.toUri(); ``` 使用`UriComponentsBuilder`构建位置 URI。 ```java return ResponseEntity.created(location).build(); ``` 返回带有位置 URI 的响应实体。 `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); } } ``` 这是一个简单的`Post` bean。它具有两个属性：`id`和`content`。 `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 { 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 Post save(Post p) { var post = new Post(counter.incrementAndGet(), p.getContent()); this.posts.add(post); return post; } public Set<Post> all() { return this.posts; } } ``` `PostService`具有保存帖子并返回所有帖子的方法。我们没有实现数据库层。相反，我们使用一个简单的内存集合。 ```java $ mvn jetty:run ``` 我们运行 Jetty 服务器。 ```java $ curl -i -d "content=Post five" -X POST http://localhost:8080/posts HTTP/1.1 201 Created Date: Tue, 30 Apr 2019 09:49:10 GMT Location: http://localhost:8080/posts/5 Content-Length: 0 Server: Jetty(9.4.14.v20181114) ``` 创建一个新帖子。注意位置标头。 ```java $ curl localhost:8080/posts [{"id":3,"content":"Post three"},{"id":4,"content":"Post four"}, {"id":1,"content":"Post one"},{"id":5,"content":"Post five"},{"id":2,"content":"Post two"}] ``` 我们得到所有帖子。在本教程中，我们介绍了`@PostMapping`注解。您可能也对这些相关教程感兴趣： [Spring `@GetMapping`教程](/spring/getmapping/)， [Spring `@RequestMapping`教程](/spring/requestmapping/)， [Spring `@MatrixVariable`教程](/spring/matrixvariable/)， [Java 教程](/lang/java/)，或列出[所有 Spring 教程](/all/#spring)。