WinstoneResponseWriter.java

/*
 * Copyright 2003-2006 Rick Knowles <winstone-devel at lists sourceforge net>
 * Distributed under the terms of either:
 * - the common development and distribution license (CDDL), v1.0; or
 * - the GNU Lesser General Public License, v2.1 or later
 */
package winstone;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;

/**
 * A hacked print writer that allows us to trigger an automatic flush on
 * println operations that go over the content length or buffer size.
 *
 * This is only necessary because the spec authors seem intent of having
 * the print writer's flushing behaviour be half auto-flush and half not.
 * Damned if I know why - seems unnecessary and confusing to me.
 *
 * @author <a href="mailto:rick_knowles@hotmail.com">Rick Knowles</a>
 * @version $Id: WinstoneResponseWriter.java,v 1.3 2006/02/28 07:32:47 rickknowles Exp $
 */
public class WinstoneResponseWriter extends PrintWriter {

    private WinstoneOutputStream outputStream;
    private WinstoneResponse response;
    private int bytesBuffered;

    public WinstoneResponseWriter(WinstoneOutputStream out,
            WinstoneResponse response) throws UnsupportedEncodingException {
        super(new OutputStreamWriter(out, response.getCharacterEncoding()), false);
        this.outputStream = out;
        this.response = response;
        this.bytesBuffered = 0;
    }

    public void write(int c) {
        super.write(c);
        appendByteCount("" + ((char) c));
    }

    public void write(char[] buf, int off, int len) {
        super.write(buf, off, len);
        if (buf != null) {
            appendByteCount(new String(buf, off, len));
        }
    }

    public void write(String s, int off, int len) {
        super.write(s, off, len);
        if (s != null) {
            appendByteCount(s.substring(off, len));
        }
    }

    protected void appendByteCount(String input) {
        try {
            this.bytesBuffered += input.getBytes(response.getCharacterEncoding()).length;
        } catch (IOException err) {/* impossible */}

    }

    public void println() {
        super.println();
        simulateAutoFlush();
    }

    public void flush() {
        super.flush();
        this.bytesBuffered = 0;
    }

    protected void simulateAutoFlush() {
        String contentLengthHeader = response.getHeader(WinstoneResponse.CONTENT_LENGTH_HEADER);
        if ((contentLengthHeader != null) &&
                ((this.outputStream.getOutputStreamLength() + this.bytesBuffered) >=
                        Integer.parseInt(contentLengthHeader))) {
            Logger.log(Logger.FULL_DEBUG, Launcher.RESOURCES, "WinstoneResponseWriter.AutoFlush",
                    new String[] {contentLengthHeader,
                    (this.outputStream.getOutputStreamLength() + this.bytesBuffered) + ""});
            flush();
        }
    }
}