从Java应用程序调用Servlet时出现服务器错误

Question

Here is my Java Class by which I am calling simple servlet and passing the data, I am
using URL and HttpURlConnection class.What should be path of url for the servlet

public class TestJava
{
    public static void main(String[] args) 
{
        try 
    {
     URL url=new URL("http://localhost:9865/TestingServlet/PushServlet");

    HttpURLConnection http_url =(HttpURLConnection)   
                                            url.openConnection();
     http_url.setRequestMethod("POST");
     http_url.setDoOutput(true); 
     http_url.setDoInput(true);
     InputStream response = http_url.getInputStream();
     System.out.println(" " +response);
     ObjectOutputStream objOut = new    
             ObjectOutputStream(http_url.getOutputStream());
     objOut.writeObject("hello");
     objOut.flush();
     objOut.close();

    } 

            catch (IOException e) {

        e.printStackTrace();
    }
       }
   }

Here is the servlet code, I am receiving the object from the java code and displaying
it on the console.

  public class PushServlet extends HttpServlet 
   {
        public void doPost(HttpServletRequest request, HttpServletResponse response) 
          throws  ServletException, IOException
         {

          try 
               {

                    System.out.println("HELLO This is servlet");
                ObjectInputStream objIn = new 
                    ObjectInputStream(request.getInputStream());
                TestJava p = null;
                p = (TestJava) objIn.readObject();
                System.out.println("Servlet received p: "+p);       
              } 
                 catch (Throwable e) 
                 {
                    e.printStackTrace(System.out);
             }
    }

My web.xml is like this

 <welcome-file-list>
 <welcome-file>
 Customer_Servlet
  </welcome-file>
  </welcome-file-list>
    <servlet>
    <servlet-name>PushServlet</servlet-name>
    <servlet-class>com.servlet.PushServlet</servlet-class>
   </servlet>
    <servlet-mapping>
     <servlet-name>PushServlet</servlet-name>
     <url-pattern>/PushServlet</url-pattern>
     </servlet-mapping>
     <session-config>
      <session-timeout>50</session-timeout>
      </session-config>
      </web-app>

When im trying to run the java code on server ie Apache server, I'm getting
error HTTP Status 404 i am not able to find why i am getting this server error My code is all about invoking the servlet from java application

 please help me guys .

Answer 1

So to answer your question : "What should be path of url for the servlet?" I think you should know the following :

The URL should be something like :

http://localhost:portNumber/nameOfTheContext/MappingOfTheServlet WHERE

portNumber = the port number of the server ( Apache has it by default to 80 but Apache Tomcat has it to 8080, so it's not 9865 unless you changed it from configuration file)
nameOfTheContext = the name of the folder/archive( with .WAR or .EAR extension) which you deployed to the server
MappingOfTheServlet = the mapping of the servlet which you put in web.xml. So if you have <url-pattern>/PushServlet</url-pattern> then the mapping is PushServlet.

So having that said the URL for you should be :

http://localhost:8080/NameOfTheContext/PushServlet

If it's unclear where you can find the NameOfTheContext tell us how did you deployed the servlet , so we may help you.

Later Edit : the name of the context should be : JavaToServlet because that's the name of your .WAR archive . So your URL should be : http://localhost:9865/JavaToServlet/PushServlet

Answer 2

From the reference on web for 404 Error WiKi

The web site hosting server will typically generate a "404 Not Found" web page when a user attempts to follow a broken or dead link;

You can more about 404 error from below link
404 Not Found Error (What It Is and How To Fix It) .