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Spring @RequestMapping

last modified October 18, 2023

In this article we show how to use @RequestMapping annotation in a classic Spring web application. The annotation is used for mapping web requests onto handler methods in request-handling classes.

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

@RequestMapping

@RequestMapping is used for mapping web requests onto handler methods in request-handling classes. The process of mapping web requests to handler methods is also called routing.

@RequestMapping has the following specializations:

@GetMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping

The annotation can be used both at the class and at the method level. If used on both levels, the request paths are combined.

Spring @RequestMapping example

In the following example, we demonstrate the usage of the @RequestMapping annotation.

pom.xml
src
├───main
│ ├───java
│ │ └───com
│ │ └───zetcode
│ │ ├───config
│ │ │ MyWebInitializer.java
│ │ │ WebConfig.java
│ │ └───controller
│ │ MyController.java
│ │ TestController.java
│ └───resources
│ index.html
│ 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>RequestMappingEx</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>1.4.0</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>
 </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 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>

This is the logback.xml configuration

resources/index.html

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>Home page</title>
</head>
<body>
<p>
 This is home page.
</p>
</body>
</html>

This is a home page.

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 initializes the Spring web application. It contains one configuration class: WebConfig.

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.DefaultServletHandlerConfigurer;
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 {
 @Override
 public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
 configurer.enable();
 }
}

The WebConfig configures the Spring web application.

com/zetcode/controller/MyController.java

package com.zetcode.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import java.time.LocalTime;
@RestController
public class MyController {
 @RequestMapping(value = "/")
 public String home() {
 return "This is Home page";
 }
 @RequestMapping(value = "/about", method = RequestMethod.POST)
 public String about() {
 return "This is About page; POST request";
 }
 @RequestMapping(value = "/fresh", method = {RequestMethod.POST, RequestMethod.GET})
 public String fresh() {
 return "This is Fresh page; GET/POST request";
 }
 @RequestMapping(value = "/todo", consumes = "text/plain")
 public String todo() {
 return "This is Todo page; text/plain content type";
 }
 @RequestMapping(value = "/time", params = { "info=time" })
 public String showTime() {
 var now = LocalTime.now();
 return String.format("%s", now.toString());
 }
}

MyController various route definitions with @RequestMapping.

@RequestMapping(value = "/")
public String home() {
 return "This is Home page";
}

With value option, we map the / request path to the home handler method. If not expplicitly specified, the default request method is GET. The value is an alias to the path option.

@RequestMapping(value = "/about", method = RequestMethod.POST)
public String about() {
 return "This is About page; POST request";
}

With the method option, we can narrow the handler mapping to POST requests having the /about path.

@RequestMapping(value = "/fresh", method = {RequestMethod.POST, RequestMethod.GET})
public String fresh() {
 return "This is Fresh page; GET/POST request";
}

This method can accept both GET and POST requests.

@RequestMapping(value = "/todo", consumes = "text/plain")
public String todo() {
 return "This is Todo page; text/plain content type";
}

With the consumes option we can narrow down the mapping to the requests with defined content type.

@RequestMapping(value = "/time", params = { "info=time" })
public String showTime() {
 var now = LocalTime.now();
 return String.format("%s", now.toString());
}

With the params option we narrow down the mapping to the GET requests with /time path and info=time request parameter.

com/zetcode/controller/TestController.java

package com.zetcode.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping(value="/test")
public class TestController {
 @RequestMapping(value = "/info")
 public String info() {
 return "This is info page";
 }
 @RequestMapping(path="*.do")
 public String somePage() {
 return "This is some page";
 }
}

TestController has additional two mappings.

@RestController
@RequestMapping(value="/test")
public class TestController {

We can place @RequestMapping on class, too. The path is then combined with the method paths.

@RequestMapping(value = "/info")
public String info() {
 return "This is info page";
}

This handler is mapped to the /test/info path.

@RequestMapping(path="*.do")
public String somePage() {
 return "This is some page";
}

The path option is equivalent to the value. It can accept Ant-style URL mappings.

$ mvn jetty:run

We run the Jetty server.

$ curl localhost:8080
This is Home page

We generate a GET request to the home page with curl tool.

$ curl -X POST localhost:8080/about
This is About page; POST request

This is a POST request to the /about path.

$ curl -X POST localhost:8080/fresh
This is Fresh page; GET/POST request
$ curl -X GET localhost:8080/fresh
This is Fresh page; GET/POST request

The /fresh page accepts both GET and POST requests.

$ curl -d "info=time" localhost:8080/time
13:24:29.934670700

We send a request with a parameter to the /time page.

$ curl localhost:8080/test/info
This is info page

The class-level and method-level annotations are combined into the /test/info path.

$ curl localhost:8080/test/produce.do
This is some page

Finally, the ant-style mapping.

In this article we have created created various routes with @RequestMapping 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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