Spring @RequestMapping
Spring @RequestMapping shows how to use @RequestMapping annotation in a Spring web application. The annotation is used for mapping web requests onto handler methods in request-handling classes.
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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