source: josm/src/org/openstreetmap/josm/io/ProgressReader.java@ 101

package org.openstreetmap.josm.io;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URLConnection;

import javax.swing.BoundedRangeModel;
import javax.swing.JLabel;

/**
 * Read from an other reader and increment an progress counter while on the way.
 * @author Imi
 */
public class ProgressReader extends Reader {

        private final Reader in;
        private final BoundedRangeModel progress;
        private final JLabel currentAction;
        private int readSoFar = 0;

        public ProgressReader(URLConnection con, BoundedRangeModel progress, JLabel currentAction) throws IOException {
                this.in = new InputStreamReader(con.getInputStream());
                this.progress = progress;
                this.currentAction = currentAction;
                int contentLength = con.getContentLength();
                if (contentLength > 0)
                        progress.setMaximum(contentLength);
                else
                        progress.setMaximum(0);
                progress.setValue(0);
    }

        @Override public void close() throws IOException {
                in.close();
        }

        @Override public int read(char[] cbuf, int off, int len) throws IOException {
                int read = in.read(cbuf, off, len);
                readSoFar += read;

                String progStr = " ("+readSoFar+"/";
                if (progress.getMaximum() == 0)
                        progStr += "???)";
                else
                        progStr += progress.getMaximum()+")";
                
                String cur = currentAction.getText();
                int i = cur.indexOf(' ');
                if (i != -1)
                        cur = cur.substring(0, i) + progStr;
                else
                        cur += progStr;
                currentAction.setText(cur);
                progress.setValue(readSoFar);
                return read;
        }

}