Spring @PathVariable
Spring @PathVariable tutorial shows how to read a URL variable with @PathVariable annotation.
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.
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>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.
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/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[]{"/"};
}
}
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.
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;
@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.
com/zetcode/controller/MyController.java
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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