last modified October 18, 2023
Spring @MatrixVariable tutorial shows how to parse URL parameters with @MatrixVariable.
Spring is a popular Java application framework for creating enterprise applications.
@MatrixVariable is used to parse name-value pairs within a path segment
and bind them to method parameters. Multiple pairs are separated with semicolon.
Matrix variables must be enabled first.
The following application parses name-value pairs from the URL path segments.
pom.xml src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ ├───config │ │ │ MyWebInitializer.java │ │ │ WebConfig.java │ │ └───controller │ │ MyController.java │ ├───resources │ └───webapp │ index.html └───test └───java
This is the project structure.
<?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>matrixvariableex</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>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 file, we have the project dependencies.
package com.zetcode.config;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;
import org.springframework.web.servlet.FrameworkServlet;
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.
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.PathMatchConfigurer;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.util.UrlPathHelper;
@Configuration
@EnableWebMvc
@ComponentScan(basePackages = {"com.zetcode"})
public class WebConfig implements WebMvcConfigurer {
@Override
public void configurePathMatch(PathMatchConfigurer configurer) {
var urlPathHelper = new UrlPathHelper();
urlPathHelper.setRemoveSemicolonContent(false);
configurer.setUrlPathHelper(urlPathHelper);
}
@Override
public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
configurer.enable();
}
}
The WebConfig configures the Spring web application.
@Override
public void configurePathMatch(PathMatchConfigurer configurer) {
var urlPathHelper = new UrlPathHelper();
urlPathHelper.setRemoveSemicolonContent(false);
configurer.setUrlPathHelper(urlPathHelper);
}
Here we enable matrix variables.
package com.zetcode.controller;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.MatrixVariable;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import java.util.Map;
@RestController
public class MyController {
@GetMapping(value = "/user/{first}/{last}",
produces = MediaType.TEXT_PLAIN_VALUE)
public String handler1(@MatrixVariable("first") String first,
@MatrixVariable("last") String last) {
return String.format("Hello %s %s", first, last);
}
@GetMapping(value = "/data/{user:.*}",
produces = MediaType.TEXT_PLAIN_VALUE)
public String handler2(@MatrixVariable Map<String, String> data) {
return String.format("Id: %s\nFirst name: %s\nLast Name: %s\nEmail: %s\n",
data.get("id"), data.get("first"), data.get("last"), data.get("email"));
}
@GetMapping(value = "/geo/{continent}",
produces = MediaType.TEXT_PLAIN_VALUE)
public String handler3(@PathVariable("continent") String continent,
@MatrixVariable("country") String country,
@MatrixVariable("capital") String capital) {
return String.format("Continent: %s\nCountry: %s\nCapital: %s\n",
continent, country, capital);
}
}
MyController contains mappings of request paths to handler methods.
@GetMapping(value = "/user/{first}/{last}",
produces = MediaType.TEXT_PLAIN_VALUE)
public String handler1(@MatrixVariable("first") String first,
@MatrixVariable("last") String last) {
return String.format("Hello %s %s", first, last);
}
Here we bind multiple matrix variables to method parameters with @MatrixVariable.
@GetMapping(value = "/data/{user:.*}",
produces = MediaType.TEXT_PLAIN_VALUE)
public String handler2(@MatrixVariable Map<String, String> data) {
return String.format("Id: %s\nFirst name: %s\nLast Name: %s\nEmail: %s\n",
data.get("id"), data.get("first"), data.get("last"), data.get("email"));
}
Here we map multiple name-value pairs into a map.
@GetMapping(value = "/geo/{continent}",
produces = MediaType.TEXT_PLAIN_VALUE)
public String handler3(@PathVariable("continent") String continent,
@MatrixVariable("country") String country,
@MatrixVariable("capital") String capital) {
return String.format("Continent: %s\nCountry: %s\nCapital: %s\n",
continent, country, capital);
}
In the third case, we combine @MatrixVariable with @PathVariable.
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Home page</title> </head> <body> <p> <a href="http://localhost:8080/user/first=John/last=Doe">Greet user</a> </p> <p> <a href="http://localhost:8080/data/id=1;first=John;last=Doe;email=johndoe@gmail.com">Show user data</a> </p> <p> <a href="http://localhost:8080/geo/Europe;country=Slovakia;capital=Bratislava">Show country info</a> </p> </body> </html>
This is the home page. We have three links that contain name-value pairs which are parsed with
@MatrixVariable annotations.
In this article we have used @MatrixVariable to parse name-value pairs on the
path segments and bind them to method parameters.
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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