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.

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>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.

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/bean/User.java

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.

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.

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; 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.

com/zetcode/controller/MyController.java

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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