Spring @PostMapping

last modified October 18, 2023

Spring @PostMapping tutorial shows how to use @PostMapping annotation to map HTTP POST requests onto specific handler methods.

Spring is a popular Java application framework for creating enterprise applications.

@PostMapping

@PostMapping annotation maps HTTP POST requests onto specific handler methods. It is a composed annotation that acts as a shortcut for @RequestMapping(method = RequestMethod.POST).

Spring @PostMapping example

The following application uses @PostMapping to create a new resource. In this example, we use annotations to set up a Spring web application.

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

This is the project structure.

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>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
    <spring-version>5.3.23</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>${spring-version}</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.13.4</version>
    </dependency>

</dependencies>

<build>
    <plugins>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>3.3.2</version>
        </plugin>

        <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <version>9.4.49.v20220914</version>
        </plugin>

    </plugins>
</build>

</project>

In the pom.xml file we have the project dependencies.

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>

The logback.xml is a configuration file for the Logback logging library.

com/zetcode/config/MyWebInitializer.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 registers the Spring DispatcherServlet, which is a front controller for a Spring web application.

@Override protected Class<?>[] getServletConfigClasses() {

return new Class[]{WebConfig.class};

}

The getServletConfigClasses returns a web configuration class.

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 {

}

The WebConfig enables Spring MVC annotations with @EnableWebMvc and configures component scanning for the com.zetcode package.

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;

@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 provides mappings between request paths and handler methods.

Note: it is a good practice to return the location of the newly created resource in the response header.

@PostMapping(value = “/posts”) public ResponseEntity<Post> createPost(HttpServletRequest request, UriComponentsBuilder uriComponentsBuilder) {

The @PostMapping maps the createPost method to the /posts URL.

var content = request.getParameter(“content”);

We get the content parameter of the POST request.

var post = new Post(); post.setContent(content);

post = postService.save(post);

A new post is created and saved with a post service.

UriComponents uriComponents = uriComponentsBuilder.path("/posts/{id}”).buildAndExpand(post.getId()); var location = uriComponents.toUri();

With UriComponentsBuilder we build the location URI.

return ResponseEntity.created(location).build();

A response entity with the location URI is returned.

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);
}

}

This is a simple Post bean. It has two attributes: id and 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;

@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;
}

}

A PostService has methods to save a post and return all posts. We do not implement a database layer; instead we use a simple in-memory collection.

$ mvn jetty:run

We run the Jetty server.

$ curl -i -d “content=Post five” -X POST http://localhost:8080/posts HTTP/1.1 201 Created Date: Thu, 22 Sep 2022 09:10:11 GMT Location: http://localhost:8080/posts/5 Content-Length: 0 Server: Jetty(9.4.49.v20220914)

A new post is created. Notice the location header.

$ 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”}]

We get all posts.

In this article we have presented the @PostMapping annotation.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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