livelessons-web-transforms

Lesson 9: Developing Web Applications (Transforms)

Introduction

Builds on the templating example to show how you can use Spring’s resource resolvers and transformers to implement cache-busting.

Building and running the sample

Use the following commands to build run the application:

$ mvn clean package
$ java -jar target/livelessons-web-transforms-1.0.0-SNAPSHOT.jar

Understanding the code

The WebTransformsApplication class includes addition configuration to register special resource handlers that “fingerprint” URLs. When application.devmode is set to false in the application.properties two different version resolver strategies are used. All JavaScript resources are prefixed with an application ID, and any other resource is post-fixed with a SHA of its content.

To test the application open a browser to http://localhost:8080 and enable networking tools. Notice how URLs inside the page are rewritten (e.g. /css/page.css and all its @imports). If you hit return in the browser URL bar you’ll notice that only a single request is needed to re-render the page. If you turn set application.devmode to true and repeat the experiment you’ll notice that multiple request are made when the page is refreshed.