War vs. War Exploded: Which Deployment Mode Is Right for Your Java Web App?

Difference between war and war exploded

When deploying a Tomcat server from IntelliJ IDEA, you may encounter a choice between war and war exploded. The two modes differ as follows:

war mode: the web project is packaged as a WAR file and uploaded to the server. war exploded mode: the web project’s directory structure is uploaded directly to the server.

(1) war mode is a traditional deployment where the project is first built into a WAR archive before being deployed.

(2) war exploded mode copies the folder, JSP pages, classes, etc., directly into Tomcat’s deployment directory, enabling hot deployment, which is commonly used during development.

(3) For hot deployment, Tomcat must be configured so that changes to JSPs are reflected immediately.

Pitfalls when using war mode

1. Project structure

The project is an SSM (Spring‑MVC, Spring, MyBatis) application.

2. Tomcat location used for deployment

3. Code for obtaining the absolute path of the context

4. Experimental process and results for both modes

(1) Using war mode, the following code returns the project’s relative path:

The path obtained is:

where C:\Software\apache-tomcat-8.0.32 is the Tomcat installation directory. This shows that war mode resolves to the deployment location of the packaged WAR.

(2) Using war exploded mode with the same code yields a different result, pointing to the project’s target directory.

Thus the two deployment modes produce different paths when retrieving the project’s relative location.

5. Summary

Based on the experiments, the war and war exploded modes deploy the application differently, leading to distinct results when obtaining the project’s relative path.