http status 404 : the required resource is not found

问题

I creat a web application using eclipse and tomcat7 I had the following code in the html file and the java servlet class in the html file:

<form action="UserAccessServlet" method = "get">

in the servlet class I had

@WebServlet ("/UserAccessServlet")

then I just made some small changes (new println statements) but it shows no effect I changed the server name with the following peice of code

html file: <form action="SQA_Servlet" method = "get"> java class: @WebServlet ("/SQA_Servlet")

but it seems that no reload take place and I got the following error:

HTTP Status 404 - /SQA_Learning/SQA_Servlet

--------------------------------------------------------------------------------

type Status report

message /SQA_Learning/SQA_Servlet

description The requested resource (/SQA_Learning/SQA_Servlet) is not available.

I tried clean the module, refresh, close the reopen the project with the same result

I replaced @WebServlet ("/SQA_Servlet") with @WebServlet(urlPatterns={"/SQA_Servlet"})

and still have no effect.. any suggestion.

回答1:

The WebServlet name attribute cannot start with a /. Rather do,

@WebServlet("UserAccessServlet")

or leave it blank (if you want the WebServlet to use the name of your Servlet class name. Example:

@WebServlet
public class UserAccessServlet extends HttpServlet {


//Do stuff
}

I would recommend declaring your WebServlet annotations fully like in this example.

回答2:

I'm not sure when and in what for conditions you are receiving this error. But if you are deploying to tomcat, the following might occur:

Assuming your webapp is called "my.webapp" resulting in my.webapp.war assuming you have a Servlet "servlet1" which performs action1 => @WebServlet(urlPatterns = "/action1") (note the slash in front of action1)

Assuming you are calling this action with a html form: <form action="/action1" method="GET"> this might not work because of the slash in front of action1

When it's there tomcat will redirect to localhost:8080/action1?.. while it should redirect to localhost:8080/my.project/action1?..

Solution alter the html so the form looks like: <form action="action1" method="GET">, don't change the @WebServlet(urlPatterns = "/action1")

Hope this helps someone!

来源：https://stackoverflow.com/questions/5786857/http-status-404-the-required-resource-is-not-found

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java