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Spring forward tutorial

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:

Redirect:

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>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <spring-version>5.1.3.RELEASE</spring-version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</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>5.1.3.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.1.3.RELEASE</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>3.2.2</version>
            </plugin>

            <plugin>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-maven-plugin</artifactId>
                <version>9.4.14.v20181114</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 tutorial, we have performed a forward in a Spring controller.

You might also be interested in these related tutorials: Spring Redirect tutorial, Java tutorial, or list all Spring tutorials.