Spring forward tutorial
Spring forward tutorial shows how to forward a request in a Spring web application.
Spring forward tutorial
last modified October 18, 2023
Spring forward tutorial shows how to forward a request in a Spring web application.
Spring is a popular Java application framework for creating enterprise applications.
Forward
The special forward: prefix in a view name performs a forward to different URL. Forwarding a URL transfers the request internally within the same server without involving the client browser. Forwards are performed less often than redirects.
Redirect vs Forward
A request can be basically processed in three ways: a) resolved by Spring in a controller action, b) forwarded to a different controller action, c) redirected to client to fetch another URL.
Forward:
- performed internally by Spring
- the browser is completely unaware of forward, so its original URL remains intact
- a browser reload of the resulting page repeats the original request, with the original URL
- data sent in the request is available to the forwarded action
Redirect:
- is a two step process
- Spring instructs the browser to fetch a second URL, which differs from the original
- a browser reload of the second URL will not repeat the original request, but will rather fetch the second URL
- data sent in the original request scope is not available to the second request
Spring Forward example
The following application uses forwards to a different URL after a form submission. It performs a forward with the forward: prefix.
pom.xml src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ ├───config │ │ │ MyWebInitializer.java │ │ │ WebConfig.java │ │ └───controller │ │ MyController.java │ └───resources │ │ logback.xml │ │ │ └───templates │ show.ftl └───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>springforwardex</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>5.3.23</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>5.3.23</version>
</dependency>
<dependency>
<groupId>org.freemarker</groupId>
<artifactId>freemarker</artifactId>
<version>2.3.28</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 necessary 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>
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[]{"/"};
}
}
MyWebInitializer registers the Spring DispatcherServlet, which is a front controller for a Spring web application.
@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.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.config.annotation.EnableWebMvc; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer; import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer; import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver;
@Configuration @EnableWebMvc @ComponentScan(basePackages = {“com.zetcode”}) public class WebConfig implements WebMvcConfigurer {
@Bean
public FreeMarkerViewResolver freemarkerViewResolver() {
var resolver = new FreeMarkerViewResolver();
resolver.setCache(true);
resolver.setSuffix(".ftl");
return resolver;
}
@Bean
public FreeMarkerConfigurer freemarkerConfig() {
var freeMarkerConfigurer = new FreeMarkerConfigurer();
freeMarkerConfigurer.setTemplateLoaderPath("classpath:/templates/");
return freeMarkerConfigurer;
}
}
WebConfig configures Freemarker. We set the template files location to templates directory on the classpath. (The resources is on the classpath.)
com/zetcode/controller/MyController.java
package com.zetcode.controller;
import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestParam;
@Controller public class MyController {
private static final Logger logger = LoggerFactory.getLogger(MyController.class);
@GetMapping(value = "/sendname")
public String send(@RequestParam(defaultValue = "guest") String name, Model model) {
logger.info("sendname called");
model.addAttribute("name", name);
return "forward:/newpage";
}
@GetMapping(value = "/newpage")
public String newpage() {
logger.info("newpage called");
return "show";
}
}
MyController provides two GET mappings.
@GetMapping(value = “/sendname”) public String send(@RequestParam(defaultValue = “guest”) String name, Model model) {
logger.info("send name called");
model.addAttribute("name", name);
return "forward:/newpage";
}
A request sent to /sendname is processed by send action. A request parameter is read and added to the model. In the end, it is forwarded to a new controller action.
@GetMapping(value = “/newpage”) public String newpage() {
logger.info("newpage called");
return "show";
}
The newpage action resolves the request to a show view.
resources/templates/show.ftl
<!DOCTYPE html> <html lang=“en”> <head> <meta charset=“UTF-8”> <title>Show</title> <meta name=“viewport” content=“width=device-width, initial-scale=1”> </head> <body>
<p> User name: ${name} </p>
</body> </html>
The show.ftl display the user name.
$ mvn jetty:run
We run the server and locate to localhost:8080/sendname?name=Peter.
09:52:11.636 INFO com.zetcode.controller.MyController - sendname called 09:52:11.653 INFO com.zetcode.controller.MyController - newpage called
The server log contains these lines.
In this article we have performed a forward in a Spring controller.
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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