tomcat requested resource () is not available [dup

2020-07-06 02:32发布

问题:

i know its a very common question as i find many questions relating to this in several forums, including SO. but i have not found a solution yet my web.xml (located in WEB-INF)

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>SMSProjectNew</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>ReceiveMessagesServlet</display-name>
    <servlet-name>ReceiveMessagesServlet</servlet-name>
    <servlet-class>com.sendreceive.ReceiveMessagesServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ReceiveMessagesServlet</servlet-name>
    <url-pattern>/ReceiveMessagesServlet</url-pattern>
  </servlet-mapping>
</web-app>

the html page index.html, located in WebContent folder

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
The application started successfully version 1:27
<form action="/ReceiveMessagesServlet" method="post">
<input type="text" name="number"/>
<input type="text" name="message"/>
<input type="submit" name="submit"/>
</form> 
</body>
</html>

finally the servlet, ReceiveMessagesServlet, located in src\com.sendreceive package com.sendreceive;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

   public class ReceiveMessagesServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ReceiveMessagesServlet() {
        super();
        // TODO Auto-generated constructor stub
    }


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }

    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response) {
        String responseMessage = request.getParameter("message");
        String responseNumber = request.getParameter("number");
        System.out.println(responseMessage+responseNumber);
    }

}

i have installed the tomcat plugin in eclipse. when i right click on the project and then click on run the project on server. tomcat server starts in eclipse and the index.html page is shown..but when i enter some values in the fields and click submit..it gives the 404 error..i have been struggling from past 2 hours..kindly help..also..fyi, i am using this tutorial http://www.ibm.com/developerworks/opensource/library/os-eclipse-tomcat/index.html

回答1:

You are getting 404 error because of the action="/ReceiveMessagesServlet", please remove the slash. Try with action="ReceiveMessagesServlet".

When you add a slash to URL pattern then the container will look for a web application deployed with name 'ReceiveMessagesServlet'.Since this not there you will receive 404 error.



回答2:

When you deploy your application into servlet container, your URLs may be prefixed by the context path identifying your application among other applications in that container (i.e. /ReceiveMessagesServlet becomes /MyApp/ReceiveMessagesServlet).

Therefore you should take that possibility into account and modify your URLs accordingly, for example, with JSTL's <c:url>:

<form action="<c:url = value = '/ReceiveMessagesServlet' />" method="post"> 

Alternatively, without JSTL:

<form action="${pageContext.request.contextPath}/ReceiveMessagesServlet" method="post"> 


回答3:

Errors in your servlet may cause Tomcat to mark it as unavailable as I got in my server log:

06/02/2013 13:32:43 org.apache.catalina.core.ApplicationContext log INFO: Marking servlet Imager as unavailable 06/02/2013 13:32:43 org.apache.catalina.core.StandardWrapperValve invoke SEVERE: Allocate exception for servlet Imager java.lang.ClassNotFoundException com.project.test.ImageThumber

You should look the log for reasons. In my case a missing jar with some test classes.