Spring @RequestBody

last modified October 18, 2023

Spring @RequestBody tutorial shows how to bind method parameters to request body with @RequestBody annotation.

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

Spring @RequestBody

@RequestBody annotation binds request body to method parameters. The process of serialization/deserialization is performed by HttpMessageConverter. In addition, automatic validation can be applied by annotating the argument with @Valid.

Spring @RequestBody example

The application binds request body parameters of a form POST and JSON post request to mapped method arguments.

pom.xml
src
├───main
│ ├───java
│ │ └───com
│ │ └───zetcode
│ │ ├───bean
│ │ │ User.java
│ │ ├───config
│ │ │ MyWebInitializer.java
│ │ │ WebConfig.java
│ │ └───controller
│ │ MyController.java
│ └───resources
│ logback.xml
└───test
 └───java

This is the project structure.

<?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>springrequestbodyex</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>ch.qos.logback</groupId>
 <artifactId>logback-classic</artifactId>
 <version>1.4.1</version>
 </dependency>
 <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>

We declare the necessary dependencies. The jackson-databind is needed for serialization in HttpMessageConverter. The application runs on embedded Jetty; therefore, we declare jetty-maven-plugin.

<?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.

package com.zetcode.bean;
import java.util.Objects;
public class User {
 private String name;
 private String occupation;
 public User() {
 }
 public User(String name, String occupation) {
 this.name = name;
 this.occupation = occupation;
 }
 public String getName() {
 return name;
 }
 public void setName(String name) {
 this.name = name;
 }
 public String getOccupation() {
 return occupation;
 }
 public void setOccupation(String occupation) {
 this.occupation = occupation;
 }
 @Override
 public boolean equals(Object o) {
 if (this == o) return true;
 if (o == null || getClass() != o.getClass()) return false;
 User user = (User) o;
 return Objects.equals(name, user.name) && Objects.equals(occupation, user.occupation);
 }
 @Override
 public int hashCode() {
 return Objects.hash(name, occupation);
 }
 @Override
 public String toString() {
 final StringBuilder sb = new StringBuilder("User{");
 sb.append("name='").append(name).append('\'');
 sb.append(", occupation='").append(occupation).append('\'');
 sb.append('}');
 return sb.toString();
 }
}

In the example, we have User bean which has name and occupation properties.

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.

package com.zetcode.config;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
@EnableWebMvc
@ComponentScan(basePackages = {"com.zetcode"})
public class WebConfig implements WebMvcConfigurer {
}

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

package com.zetcode.controller;
import com.zetcode.bean.User;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class MyController {
 private static final Logger logger = LoggerFactory.getLogger(MyController.class);
 @ResponseStatus(value = HttpStatus.OK)
 @PostMapping(value="/vals")
 public void process(@RequestBody MultiValueMap values) {
 logger.info("Values:{}", values);
 }
 @ResponseStatus(value = HttpStatus.OK)
 @PostMapping(value="/user", consumes = MediaType.APPLICATION_JSON_VALUE)
 public void process2(@RequestBody User user) {
 logger.info("User: {}", user);
 }
}

In MyContoller, we have two POST mappings. We use @RequestBody to bind request parameters to MultiValueMap and User bean. The bound values are shown in logs.

$ mvn jetty:run

We start the server.

$ curl -i -d "par1=val1&par2=val2" -X POST http://localhost:8080/vals

With the curl tool, we create a reqest to the first mapping. This creates a form POST data request (content-type is application/x-www-form-urlencoded).

11:57:39.049 INFO com.zetcode.controller.MyController - Values:{par1=[val1], par2=[val2]}

We get this log.

$ curl -i -H "Content-Type: application/json" -d "{\"name\":\"John Doe\",\"occupation\":\"gardener\"}" -X POST "http://localhost:8080/user"

We invoke the second mapping. Here we create a request with JSON data. Note that on Windows we need to escape the double quotes.

12:02:33.817 INFO com.zetcode.controller.MyController - User: User{name='John Doe', occupation='gardener'}

This is the output in the log.

In this article, we have used the @RequestBody annotation to bind request attributes to method parameters.

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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