Note: Use the clean command on the project in eclipse: mandatory check and redeploy the project;

Problem description : Sometimes, the program clearly has no problem, but it will prompt a 404 error when visiting.

Obviously there is no problem with the url address, but the resource cannot be accessed; (as follows, inaccessible/management is defined in a Servlet class, when the parameter method=show_create, it will be redirected to a jsp;)

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Solution: Use the clean function

 

In this way, the project will only be restarted afterwards, and you can access it normally.

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The role of clean:

The first part: quoted from: How to clean the project in Eclipse and the role of clean this blog;

The second part: quoted from: the role of project clean in eclipse this blog;