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程序方法。
Spring 是用于创建企业应用的流行 Java 应用框架。
@PostMapping
@PostMapping注释将 HTTP POST 请求映射到特定的处理程序方法。 它是一个组合的注释，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。
pom.xmlsrc├───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
<?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
<?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
package com.zetcode.config;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;@Configurationpublic 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。
@Overrideprotected Class<?>[] getServletConfigClasses() { return new Class[]{WebConfig.class};}getServletConfigClasses()返回 Web 配置类。
com/zetcode/config/WebConfig.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软件包配置组件扫描。
com/zetcode/controller/MyController.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;@Controllerpublic 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程序方法之间的映射。
注：这是一个很好的做法，在响应头返回新创建资源的位置。
@PostMapping(value = "/posts")public ResponseEntity<Post> createPost(HttpServletRequest request, UriComponentsBuilder uriComponentsBuilder) {@PostMapping将createPost()方法映射到/posts URL。
var content = request.getParameter("content");我们获得 POST 请求的content参数。
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。
UriComponents uriComponents = uriComponentsBuilder.path("/posts/{id}").buildAndExpand(post.getId());var location = uriComponents.toUri();使用UriComponentsBuilder构建位置 URI。
return ResponseEntity.created(location).build();
返回带有位置 URI 的响应实体。
com/zetcode/model/Post.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
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;@Servicepublic 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。
$ mvn jetty:run
我们运行 Jetty 服务器。
$ curl -i -d "content=Post five" -X POST http://localhost:8080/postsHTTP/1.1 201 CreatedDate: Tue, 30 Apr 2019 09:49:10 GMTLocation: http://localhost:8080/posts/5Content-Length: 0Server: Jetty(9.4.14.v20181114)
创建一个新帖子。 注意位置标头。
$ 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。
