httpposter.java

J2ME MIDP_Example_Applications

// Copyright 2003 Nokia Corporation.
//
// THIS SOURCE CODE IS PROVIDED 'AS IS', WITH NO WARRANTIES WHATSOEVER,
// EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS
// FOR ANY PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE
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// RIGHTS GRANTED HEREUNDER DOES NOT INFRINGE OR MAY NOT CAUSE INFRINGEMENT
// OF ANY PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OWNED OR CONTROLLED
// BY THIRD PARTIES
//
// Furthermore, information provided in this source code is preliminary,
// and may be changed substantially prior to final release. Nokia Corporation
// retains the right to make changes to this source code at
// any time, without notice. This source code is provided for informational
// purposes only.
//
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// Corporation.
// Java and all Java-based marks are trademarks or registered trademarks of
// Sun Microsystems, Inc.
// Other product and company names mentioned herein may be trademarks or
// trade names of their respective owners.
//
// A non-exclusive, non-transferable, worldwide, limited license is hereby
// granted to the Licensee to download, print, reproduce and modify the
// source code. The licensee has the right to market, sell, distribute and
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// intellectual property rights is granted herein.
package whiteboard;

import java.io.*;
import java.util.*;
import javax.microedition.io.*;
import javax.microedition.lcdui.*;

/**
 *  This class accepts and queues POST and GET requests for a particular URL,
 *  and services them in first-in-first-out order. Using the queue allows it to
 *  be thread-safe without forcing its clients ever to block. It also accept
 *  alternative MIME-types
 */
class HttpPoster
     implements Runnable
{
    protected String url;
    protected volatile boolean aborting = false;
    protected Vector requestQueue = new Vector();


    HttpPoster(String url)
    {
        this.url = url;
        Thread thread = new Thread(this);
        thread.start();
    }


    // sends a request with default MIME-type
    void sendRequest(String type, String request, HttpPosterListener listener)
        throws IOException
    {
        sendRequest(type, null, request, listener);
    }


    // sends a request with a given MIME-type
    synchronized void sendRequest(String type, String mimeType,
                                  String request, HttpPosterListener listener)
        throws IOException
    {
        // Create a new request and add it to the queue
        HttpRequest newRequest = new HttpRequest();
        newRequest.type = type;
        newRequest.request = request;
        newRequest.listener = listener;
        newRequest.mimeType = mimeType;
        requestQueue.addElement(newRequest);
        // wake up sending thread
        notify();
    }


    public void run()
    {
        running :
        while (!aborting)
        {
            HttpRequest request = null;

            synchronized (this)
            {
                while (requestQueue.size() == 0)
                {
                    try
                    {
                        // releases lock
                        wait();
                    }
                    catch (InterruptedException e)
                    {
                        // Ignore this thread is not interrupted in MIDP
                    }

                    if (aborting)
                    {
                        break running;
                    }
                }

                request = (HttpRequest) (requestQueue.elementAt(0));
                requestQueue.removeElementAt(0);
            }

            // sendRequest must have notified us
            doSend(request.type, request.mimeType, request.request, request.listener);
        }
    }



    private void doSend(String type, String mimeType,
                        String requestStr, HttpPosterListener listener)
    {
        HttpConnection conn = null;
        InputStream in = null;
        String responseStr = null;
        String errorStr = null;
        boolean wasError = false;

        try
        {
            int responseCode;
            conn = (HttpConnection) Connector.open(url);

            // Set the request method and headers
            conn.setRequestMethod(type);
            // write request
            writeRequest(conn, requestStr, mimeType);

            // read response
            responseStr = readResponse(conn);

            responseCode = conn.getResponseCode();
            if (responseCode != HttpConnection.HTTP_OK)
            {
                wasError = true;
                errorStr = "Unsupported response code: " + responseCode;
            }

            // support URL rewriting for session handling
            String rewrittenUrl = conn.getHeaderField("X-RewrittenURL");
            if (rewrittenUrl != null)
            {
                // use this new one in future
                url = rewrittenUrl;
            }
        }
        catch (IOException e)
        {
            wasError = true;
            errorStr = e.getMessage();
        }
        catch (SecurityException e)
        {
            wasError = true;
            errorStr = e.getMessage();
        }
        finally
        {
            if (conn != null)
            {
                try
                {
                    conn.close();
                }
                catch (IOException e)
                {
                    // already closing, just ignore
                }
            }
        }

        if (wasError)
        {
            listener.handleHttpError(errorStr);
        }
        else
        {
            listener.receiveHttpResponse(responseStr);
        }
    }


    private void writeRequest(HttpConnection conn, String request, String mimeType)
        throws IOException
    {
        OutputStream out = null;
        try
        {
            // sets the MIME-type if available
            if (mimeType != null)
            {
                conn.setRequestProperty("Content-Type", mimeType);
            }

            conn.setRequestProperty("Content-Length",
                                    Integer.toString(request.length()));

            // Getting the output stream may flush the headers
            out = conn.openOutputStream();
            int requestLength = request.length();
            for (int i = 0; i < requestLength; ++i)
            {
                out.write(request.charAt(i));
            }
        }
        finally
        {
            if (out != null)
            {
                try
                {
                    out.close();
                }
                catch (IOException e)
                {
                    // already closing, just ignore
                }
            }
        }
    }


    private String readResponse(HttpConnection conn)
        throws IOException
    {
        InputStream in = null;
        String responseStr = null;
        try
        {
            // Opening the InputStream will open the connection
            // and read the HTTP headers. They are stored until
            // requested.
            in = conn.openInputStream();

            // Get the length and process the data
            StringBuffer responseBuf;
            long length = conn.getLength();
            if (length > 0)
            {
                responseBuf = new StringBuffer((int) length);
            }
            else
            {
                // default length
                responseBuf = new StringBuffer();
            }

            int ch;
            while ((ch = in.read()) != -1)
            {
                responseBuf.append((char) ch);
            }
            responseStr = responseBuf.toString();
        }
        finally
        {
            if (in != null)
            {
                try
                {
                    in.close();
                }
                catch (IOException e)
                {
                    // already closing, just ignore
                }
            }
        }
        return responseStr;
    }


    // This is just for tidying up - the instance is useless after it has
    // been called
    void abort()
    {
        aborting = true;
        synchronized (this)
        {
            // wake up our posting thread and kill it
            notify();
        }
    }


    // Internal data structure to keep track of the requests
    private class HttpRequest
    {
        String type;
        String mimeType;
        String request;
        HttpPosterListener listener;
    }
}