What does `ServletContext.getRealPath('/')` do, and what are better alternatives?

What does servletcontext.getRealPath("/") mean and when should I use it?

Introduction

The ServletContext#getRealPath() converts a web application path into an absolute file system path. This absolute file system path represents the location of the web application's resources on the server's disk.

For example, "/" in the getRealPath() method represents the root of the web application. Therefore, context.getRealPath("/") would return the absolute file system path of the web application's root directory.

Usage of getRealPath()

You can use getRealPath() to perform various tasks, including:

• Access files in the web application's directory.


• Create or modify files in the web application's directory.


• Obtain a list of the files in the web application's directory.


• Get the URL of a file in the web application's directory.

Caution When Using getRealPath()

It's important to note that getRealPath() should be used with caution. If you make changes to files using getRealPath(), these changes will be lost when the web application is redeployed. This is because the changes are not saved in the original WAR file.

Additionally, getRealPath() may not always return the expected result. For example, if the server is configured to expand the WAR file into memory, getRealPath() will return null or an unexpected path.

Alternative Approaches to Accessing Files

Due to the limitations of getRealPath(), it's recommended to use the following alternative methods to access files in a web application:

• Use ServletContext#getResourceAsStream() to obtain an InputStream for a file.


• Use ServletContext#getResourcePaths() to get a list of resource paths.


• Use ServletContext#getResource() to get the URL of a file.

These methods are more portable and reliable than getRealPath().

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