Java example source code file (ProgressSource.java)

This example Java source code file (ProgressSource.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

clonenotsupportedexception, connected, delete, net, network, new, object, progressmonitor, progresssource, state, string, update, url

The ProgressSource.java Java example source code

/*
 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package sun.net;

import java.net.URL;

/**
 * ProgressSource represents the source of progress changes.
 *
 * @author Stanley Man-Kit Ho
 */
public class ProgressSource
{
    public enum State { NEW, CONNECTED, UPDATE, DELETE };

    // URL
    private URL url;
    // URL method
    private String method;
    // Content type
    private String contentType;
    // bytes read
    private long progress = 0;
    // last bytes read
    private long lastProgress = 0;
    //bytes expected
    private long expected = -1;
    // the last thing to happen with this source
    private State state;
    // connect flag
    private boolean connected = false;
    // threshold for notification
    private int threshold = 8192;
    // progress monitor
    private ProgressMonitor progressMonitor;

    /**
     * Construct progress source object.
     */
    public ProgressSource(URL url, String method) {
        this(url, method, -1);
    }

    /**
     * Construct progress source object.
     */
    public ProgressSource(URL url, String method, long expected)  {
        this.url = url;
        this.method = method;
        this.contentType = "content/unknown";
        this.progress = 0;
        this.lastProgress = 0;
        this.expected = expected;
        this.state = State.NEW;
        this.progressMonitor = ProgressMonitor.getDefault();
        this.threshold = progressMonitor.getProgressUpdateThreshold();
    }

    public boolean connected() {
        if (!connected) {
            connected = true;
            state = State.CONNECTED;
            return false;
        }
        return true;
    }

    /**
     * Close progress source.
     */
    public void close() {
        state = State.DELETE;
    }

    /**
     * Return URL of progress source.
     */
    public URL getURL() {
        return url;
    }

    /**
     * Return method of URL.
     */
    public String getMethod()  {
        return method;
    }

    /**
     * Return content type of URL.
     */
    public String getContentType()  {
        return contentType;
    }

    // Change content type
    public void setContentType(String ct)  {
        contentType = ct;
    }

    /**
     * Return current progress.
     */
    public long getProgress()  {
        return progress;
    }

    /**
     * Return expected maximum progress; -1 if expected is unknown.
     */
    public long getExpected() {
        return expected;
    }

    /**
     * Return state.
     */
    public State getState() {
        return state;
    }

    /**
     * Begin progress tracking.
     */
    public void beginTracking() {
        progressMonitor.registerSource(this);
    }

    /**
     * Finish progress tracking.
     */
    public void finishTracking() {
        progressMonitor.unregisterSource(this);
    }

    /**
     * Update progress.
     */
    public void updateProgress(long latestProgress, long expectedProgress) {
        lastProgress = progress;
        progress = latestProgress;
        expected = expectedProgress;

        if (connected() == false)
            state = State.CONNECTED;
        else
            state = State.UPDATE;

        // The threshold effectively divides the progress into
        // different set of ranges:
        //
        //      Range 0: 0..threshold-1,
        //      Range 1: threshold .. 2*threshold-1
        //      ....
        //      Range n: n*threshold .. (n+1)*threshold-1
        //
        // To determine which range the progress belongs to, it
        // would be calculated as follow:
        //
        //      range number = progress / threshold
        //
        // Notification should only be triggered when the current
        // progress and the last progress are in different ranges,
        // i.e. they have different range numbers.
        //
        // Using this range scheme, notification will be generated
        // only once when the progress reaches each range.
        //
        if (lastProgress / threshold != progress / threshold)   {
            progressMonitor.updateProgress(this);
        }

        // Detect read overrun
        if (expected != -1) {
            if (progress >= expected && progress != 0)
                close();
        }
    }

    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    public String toString()    {
        return getClass().getName() + "[url=" + url + ", method=" + method + ", state=" + state
            + ", content-type=" + contentType + ", progress=" + progress + ", expected=" + expected + "]";
    }
}