Spring Web Flow With Spring Boot | Spring Web Flow

Introduction

Spring Web Flow is a powerful framework that provides a way to implement complex web applications with a clear flow of navigation and state. It allows developers to define the flow of pages using XML or Java configuration, making it easier to manage multi-step processes. In this tutorial, we will explore how to integrate Spring Web Flow with Spring Boot, enabling rapid development of web applications.

Prerequisites

Before we begin, ensure you have the following prerequisites installed on your system:

Java Development Kit (JDK) 8 or higher
Apache Maven
An IDE (like IntelliJ IDEA, Eclipse, or Spring Tool Suite)

Setting Up the Spring Boot Project

The first step is to create a new Spring Boot project. You can do this using Spring Initializr:

Navigate to Spring Initializr and configure your project settings:

Project: Maven Project
Language: Java
Spring Boot: 2.5.5 or higher
Packaging: Jar
Java: 11 or higher
Dependencies: Spring Web, Spring Web Flow, Thymeleaf

After configuring, click on the "Generate" button to download your project.

Project Structure

Once you have downloaded and extracted your project, you will see the following structure:

                ├── src
                │   ├── main
                │   │   ├── java
                │   │   │   └── com
                │   │   │       └── example
                │   │   │           └── demo
                │   │   │               └── DemoApplication.java
                │   │   └── resources
                │   │       ├── application.properties
                │   │       └── templates
                │   └── test
                └── pom.xml

Configuring Spring Web Flow

Next, we will configure Spring Web Flow. Create a new XML file named flow.xml in the src/main/resources directory. This file will define the flow of our web application.

Here is a simple example of a flow definition:

                    <?xml version="1.0" encoding="UTF-8"?>
                    <flow xmlns="http://www.springframework.org/schema/webflow"
                          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                          xsi:schemaLocation="http://www.springframework.org/schema/webflow
                          http://www.springframework.org/schema/webflow/spring-webflow-2.5.xsd">
                        <view-state id="start" view="start">
                            <transition on="next" to="nextStep"/>
                        </view-state>

                        <view-state id="nextStep" view="nextStep">
                            <transition on="finish" to="finish"/>
                        </view-state>

                        <end-state id="finish"/>
                    </flow>

This XML defines a simple flow with three states: start, nextStep, and finish.

Creating Views with Thymeleaf

Now, let's create the views for our flow. In the src/main/resources/templates directory, create two HTML files: start.html and nextStep.html.

Here’s an example of the start.html view:

                    <!DOCTYPE html>
                    <html xmlns:th="http://www.thymeleaf.org">
                    <head>
                        <title>Start Page</title>
                    </head>
                    <body>
                        <h1>Welcome to the Start Page</h1>
                        <a th:href="@{nextStep}" th:action="next">Go to Next Step</a>
                    </body>
                    </html>

And here is an example of the nextStep.html view:

                    <!DOCTYPE html>
                    <html xmlns:th="http://www.thymeleaf.org">
                    <head>
                        <title>Next Step Page</title>
                    </head>
                    <body>
                        <h1>You are in the Next Step Page</h1>
                        <a th:href="@{finish}" th:action="finish">Finish</a>
                    </body>
                    </html>

Creating the Controller

Next, we need to create a controller to handle the flow. Create a new Java class named WebFlowController.java in the src/main/java/com/example/demo directory.

Here is an example of the controller:

                    package com.example.demo;

                    import org.springframework.stereotype.Controller;
                    import org.springframework.web.bind.annotation.RequestMapping;

                    @Controller
                    public class WebFlowController {

                        @RequestMapping("/start")
                        public String start() {
                            return "flow"; // This will return the flow defined in flow.xml
                        }
                    }

Running the Application

You can now run your Spring Boot application. Open a terminal in your project root directory and execute:

mvn spring-boot:run

Once the application is running, open your web browser and navigate to http://localhost:8080/start. You should see the start page of your Spring Web Flow application.

Conclusion

In this tutorial, we have explored how to integrate Spring Web Flow with Spring Boot. You learned how to set up a Spring Boot project, configure Spring Web Flow, create views using Thymeleaf, and define a controller to manage the flow. Spring Web Flow provides a robust framework for building complex web applications with a clear navigation structure.

Spring Web Flow with Spring Boot Tutorial