将请求从一个 servlet 转发到另一场战争中的 servlet

Question

I have an EAR1. This EAR1 has a WAR1 inside it, with a context of '/war1'. This war1 has a servlet with url-mapping of '/servlet1' inside it.

On the same instance of WebSphere, I have an EAR2. This EAR2 has a WAR2 inside it, with a context of '/war2'. This war2 has a servlet url-mapping of '/servlet2' inside it.

EAR1---- WAR 1 --- Servlet1
EAR2---- WAR 2 --- Servlet2

Now, I need to forward request from servlet1 to servlet 2...So, Inside servlet1, I am trying to forwrd the request this way..

getServletContext().getRequestDispatcher("/war2/servlet2").forward(request, response);

but it is failing..

how do I forward request to servlet2 that is in war2 that is in EAR2.

Thanks in advance

Answer 1

I suspect that since the RequestDispatcher lives on the ServletContext, you won't be able to forward to a different servlet. What error do you get?

It says here:

http://java.boot.by/wcd-guide/ch03s05.html

"The ServletContext.getRequestDispatcher method takes a String argument describing a path within the scope of the ServletContext."

See this post for more information:

ServletContext.getRequestDispatcher() vs ServletRequest.getRequestDispatcher()

Answer 2

As per your description,you have two war files( war1 ,and war2 ),so it means you are having two context in same server.

In order to access the resource in different context you can do below.

ServletContext ctx = request.getServletContext().getContext("/war2");
RequestDispatcher dispatcher = ctx.getRequestDispatcher("/servlet2");
dispatcher.forward(request, response);

Answer 3

I do it with HttpUrlConnection as below:

// variable methodType is GET or POST in method call below

private void sendToAnotherServletInDifferentWar(HttpServletRequest request, HttpServletResponse response, String methodType) throws IOException
    {
        HttpURLConnection conn = null;
       
        // replace/modify the path as per the path you want to hit.

        String pathToAnotherServlet = "http://localhost:8080/<war2-context>/<servlet-path>/<path-Info>";
        final URL url = new URL(pathToAnotherServlet);

        try
        {
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod(methodType);

            final Enumeration<String> headers = request.getHeaderNames();
            while (headers.hasMoreElements())
            {
                final String header = headers.nextElement();
                final Enumeration<String> values = request.getHeaders(header);
                while (values.hasMoreElements())
                {
                    final String value = values.nextElement();
                    System.out.println("header-> " + header + ": value-> " + value);
                    conn.addRequestProperty(header, value);
                }
            }

            conn.setUseCaches(false);
            conn.setDoInput(true);
            conn.setDoOutput(false);
            conn.connect();

            final byte[] buffer = new byte[16*1024];

            response.setStatus(conn.getResponseCode());
            System.out.println("HTTP Response Code obtained from service " + conn.getResponseCode());
            if(conn.getResponseCode() == HttpServletResponse.SC_OK)
            {
                for (int i = 0; ; ++i)
                {
                    final String header = conn.getHeaderFieldKey(i);
                    if (header == null)
                        break;
                    final String value = conn.getHeaderField(i);
                    response.setHeader(header, value);
                }

                while (true)
                {
                    final int read = conn.getInputStream().read(buffer);
                    if (read <= 0)
                        break;
                    response.getOutputStream().write(buffer, 0, read);
                }
            }
            else {
                response.sendError(conn.getResponseCode(), conn.getResponseMessage());
            }
        }
        catch (IOException e)
        {
            logger.error("Calling service Failed with cause ", e);
            if(conn != null)
                response.sendError(conn.getResponseCode(), e.getMessage());
            else
                response.sendError(HttpServletResponse.SC_BAD_REQUEST, e.getMessage());
        }
    }