CopyStrategyImpl.java

package net.java.dev.weblets.util;

import java.io.*;
import java.net.SocketException;

/**
 * @author werpu
 * @date: 22.09.2008
 */
public class CopyStrategyImpl implements CopyStrategy {
    public void copy(String webletName, String contentType, InputStream in, OutputStream out) throws IOException {
        boolean isText = isText(contentType);
        if (isText)
            copyText(webletName, new InputStreamReader(in), new OutputStreamWriter(out));
        else
            copyStream(in, out);
    }

    private boolean isText(String contentType) {
        return contentType != null && (contentType.startsWith("text/") || contentType.endsWith("xml") || contentType.equals("application/x-javascript"));
    }

    /**
     * wraps the input stream from our given request into another input stream
     *
     * @param webletName the name of the affected weblet
     * @param mimetype   the response mimetype
     * @param in         our given input steam
     * @return a wrapped input stream with our filterng cascade in place
     * @throws IOException in case of an error
     */
    public InputStream wrapInputStream(String webletName, String mimetype, InputStream in) throws IOException {
        if (isText(mimetype)) {
            BufferedReader bufIn = new BufferedReader(mapResponseReader(webletName, new InputStreamReader(in)));
            return new ReaderInputStream(bufIn);
        }
        return new BufferedInputStream(mapInputStream(in));
    }

    protected BufferedWriter mapResponseWriter(Writer out) {
        return new BufferedWriter(out);
    }

    protected BufferedReader mapResponseReader(String webletName, Reader in) {
        return new TextProcessingReader(in, webletName);
    }

    protected BufferedInputStream mapInputStream(InputStream in) {
        return new BufferedInputStream(in);
    }

    protected BufferedOutputStream mapOutputStream(OutputStream out) {
        return new BufferedOutputStream(out);
    }

    protected void copyText(String webletName, Reader in, Writer out) throws IOException {
        BufferedReader bufIn = mapResponseReader(webletName, in);
        BufferedWriter bufOut = mapResponseWriter(out);
        try {
            String line = null;
            try {
                while ((line = bufIn.readLine()) != null) {
                    bufOut.write(line);
                    bufOut.write("\n");
                }

            } catch(SocketException e) {
                // This happens sometimes with Microsft Internet Explorer. It would
                // appear (guess) that when javascript creates multiple dom nodes
                // referring to the same remote resource then IE stupidly opens
                // multiple sockets and requests that resource multiple times. But
                // when the first request completes, it then realises its stupidity
                // and forcibly closes all the other sockets. But here we are trying
                // to service those requests, and so get a "broken pipe" failure
                // on write. The only thing to do here is to silently ignore the issue,
                // ie suppress the exception. Note that it is also possible for the
                // above code to succeed (ie this exception clause is not run) but
                // for a later flush to get the "broken pipe"; this is either due
                // just to timing, or possibly IE is closing sockets after receiving
                // a complete file for some types (gif?) rather than waiting for the
                // server to close it.

                //Note we fix it here, because this is the central core of the processing
                //deepest level sort of
                //we do not need to touch our writers that way 

              
            }
        } finally {
            closeBuffers(bufIn, bufOut);
        }
    }

    protected void copyStream(InputStream in, OutputStream out) throws IOException {
        byte[] buffer = new byte[2048];
        BufferedInputStream bufIn = mapInputStream(in);
        BufferedOutputStream bufOut = mapOutputStream(out);
        int len = 0;
        int total = 0;
        try {
            try {
                while ((len = bufIn.read(buffer)) > 0) {
                    bufOut.write(buffer, 0, len);
                    total += len;
                }
            } catch(SocketException e) {
                // This happens sometimes with Microsft Internet Explorer. It would
                // appear (guess) that when javascript creates multiple dom nodes
                // referring to the same remote resource then IE stupidly opens
                // multiple sockets and requests that resource multiple times. But
                // when the first request completes, it then realises its stupidity
                // and forcibly closes all the other sockets. But here we are trying
                // to service those requests, and so get a "broken pipe" failure
                // on write. The only thing to do here is to silently ignore the issue,
                // ie suppress the exception. Note that it is also possible for the
                // above code to succeed (ie this exception clause is not run) but
                // for a later flush to get the "broken pipe"; this is either due
                // just to timing, or possibly IE is closing sockets after receiving
                // a complete file for some types (gif?) rather than waiting for the
                // server to close it.

                if(e.getMessage().toLowerCase().indexOf("broken pipe") != -1) {
                    return;
                }
                throw e;
            }
        } finally {
            closeBuffers(bufIn, bufOut);
		}
	}

    private void closeBuffers(Closeable bufIn, Closeable bufOut) {
        try {
            bufIn.close();
        } catch (Exception e) {
            //do nothing, there is a strange ie behavior which closes pipes upfront
        }
        try {
            bufOut.close();
        } catch (Exception e) {
            //do nothing, there is a strange ie behavior which closes pipes upfront
        }
    }
}