Spring @PathVariable

last modified October 18, 2023

Spring @PathVariable tutorial shows how to read a URL template variable with @PathVariable annotation. We create a Spring RESTful application to demonstrate the annotation.

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

@PathVariable

@PathVariable is a Spring annotation which indicates that a method parameter should be bound to a URI template variable. If the method parameter is Map<String, String> then the map is populated with all path variable names and values.

It has the following optional elements:

• name - name of the path variable to bind to
• required - tells whether the path variable is required
• value - alias for name

Spring @PathVariable example

The following example creates a Spring web application which uses @PathVariable. The values of the variables are logged.

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

This is the project structure of the Spring application.

<?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>pathvariableex</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>
 </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 project dependencies. The @PathVariable comes from spring-webmvc package.

<?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.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[]{"/"};
 }
}

DispatcherServlet, which is a front controller for a Spring web application, is registered in MyWebInitializer.

@Override
protected Class<?>[] getServletConfigClasses() {
 return new Class[]{WebConfig.class};
}

The getServletConfigClasses returns a web configuration class.

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.

package com.zetcode.controller;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;
import java.util.Map;
@RestController
public class MyController {
 private static final Logger logger = LoggerFactory.getLogger(MyController.class);
 @ResponseStatus(value = HttpStatus.OK)
 @GetMapping(value = "/user/{name}")
 public void process(@PathVariable String name) {
 logger.info("User name: {}", name);
 }
 @ResponseStatus(value = HttpStatus.OK)
 @GetMapping(value = "/user/{name}/{email}")
 public void process2(@PathVariable String name, @PathVariable String email) {
 logger.info("User name: {} and email: {}", name, email);
 }
 @ResponseStatus(value = HttpStatus.OK)
 @GetMapping(value = "/book/{author}/{title}")
 public void process3(@PathVariable Map<String, String> vals) {
 logger.info("{}: {}", vals.get("author"), vals.get("title"));
 }
}

We have three mappings for GET requests.

@ResponseStatus(value = HttpStatus.OK)
@GetMapping(value = "/user/{name}")
public void process(@PathVariable String name) {
 logger.info("User name: {}", name);
}

In this code, a URI template variable is bound to the name method parameter.

@ResponseStatus(value = HttpStatus.OK)
@GetMapping(value = "/user/{name}/{email}")
public void process2(@PathVariable String name, @PathVariable String email) {
 logger.info("User name: {} and email: {}", name, email);
}

Multiple variables can be bound, too, by specifying multiple @PathVariable annotations.

@ResponseStatus(value = HttpStatus.OK)
@GetMapping(value = "/book/{author}/{title}")
public void process3(@PathVariable Map<String, String> vals) {
 logger.info("{}: {}", vals.get("author"), vals.get("title"));
}

Multiple variables can be bound also with Map<String, String>.

$ mvn jetty:run

We start the Jetty server.

$ curl localhost:8080/user/Peter/peter@gmail.com/

We issue a request with curl.

22:04:35.273 INFO com.zetcode.controller.MyController - User name: Peter and email: peter@gmail.com

The application logs this message.

In this article, we have created a RESTful web application with Spring framework. We have demonstrated the usage of @PathVariable.

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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