downloadmanager.java

MyDownloader 是一款使用 http 协议(RFC 1867)用于下载一个或多个文件到本地的简单易用的收费 Java 程序.使用托拽操作,你可以在一个页面内下载多个文件.在下载文件的过程当中

/*
 * Copyright 2007 JavaAtWork All rights reserved.
 * Use is subject to license terms.
 */
package com.javaatwork.mydownloader.listeners;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Vector;

import com.javaatwork.mydownloader.DownloadFile;
import com.javaatwork.mydownloader.MyDownloader;
import com.javaatwork.mydownloader.dialog.ConfirmationDialog;
import com.javaatwork.mydownloader.dialog.ProgressDialog;
import com.javaatwork.mydownloader.dialog.TimeOutOptionPane;
import com.javaatwork.mydownloader.utils.LocaleManager;
import com.javaatwork.mydownloader.utils.Logger;
import com.javaatwork.mydownloader.utils.Parameters;
import com.javaatwork.mydownloader.utils.SwingWorker;
import com.javaatwork.mydownloader.utils.TempDirectoryManager;
import com.javaatwork.mydownloader.utils.Version;

/**
 * Class who is responsible for downloading the files.
 * 
 * @author Johannes Postma
 */
public class DownloadManager implements DestroyListener {

	private boolean finished = false;
	private String status = "";
	private String fileInProgress = null;
	private int numberOfFiles = 0;
	private int fileInRow = 0;
	private long totalBytesDownloaded = 0; // total bytes read of all files
	private long bytesDownloaded = 0; // bytes read of one file
	private long bytes = 0; // total byes of one file
	private Vector localFiles = new Vector();
	private long begin = 0L;
	private boolean cancel = false;
	private FileOutputStream out = null;
	private InputStream in = null;
	private ProgressDialog progressDialog = null;
	private MyDownloader applet = null;
	private HttpURLConnection conn = null;

	// this boolean is necessary to view the correct message if an error
	// if the file is already downloaded and is opened by e.g. Word
	// the downloaded file cannot be written to the filesystem again.
	private boolean fileExist = false;

	/**
	 * Downloads the files from the server and stores the files in the temp
	 * directory (System property java.io.tmpdir).
	 * 
	 * @param applet MyDownloader.
	 * @return The downloaded files stored in the temp (java.io.tmpdir)
	 *         directory.
	 */
	public File[] downloadFiles(final MyDownloader applet) {
		return downloadFiles(applet, null);
	}

	/**
	 * Downloads the files from the server and stores the files in a specific 
	 * directory. If the directory is null the files will be stored in the temp
	 * (java.io.tmpdir) directory.
	 * 
	 * @param applet MyDownloader.
	 * @param directory The directory where the files will be stored.
	 * @return The downloaded files.
	 */
	public File[] downloadFiles(final MyDownloader applet, File directory) {
		this.applet = applet;
		

		if (Version.FREE_EDITION) {
			if (showFreeDialog()) {
				return null;
			}
		}
		
		final File downloadLocation = directory == null ? TempDirectoryManager.getTempDirectory() : directory;
		final DownloadFile[] files = applet.getFilesToDownload();

		if (files == null || files.length == 0) {
			return null;
		}

		// check if files must be overwritten
		if (directory != null) {
			if (!overwrite(directory, files)) {
				return null;
			}
		}
		
		this.numberOfFiles = files.length;

		begin = System.currentTimeMillis();

		SwingWorker worker = new SwingWorker() {

			public Object construct() {

				// create a new array for the files to be download
				int counter = 0;
				
				for (int i = 0; i < files.length && !cancel; i++) {
					if (files[i].isOverwrite()) {
						counter++;
					}
				}
				
				DownloadFile [] downFiles = new DownloadFile[counter];
				counter = 0;
				
				for (int i = 0; i < files.length && !cancel; i++) {
					if (files[i].isOverwrite()) {
						downFiles[counter] = files[i];
						counter++;
					}
				}
				
				numberOfFiles = downFiles.length;
				
				for (int i = 0; i < downFiles.length && !cancel; i++) {
					downloadFile(downloadLocation, downFiles[i].getUrl(), downFiles[i].getFileName(), applet.getCodeBase());
				}

				finished = true;

				return null;
			}
		};

		progressDialog = new ProgressDialog(applet, this);

		worker.start();
		progressDialog.start();

		
		return (File[]) localFiles.toArray(new File[localFiles.size()]);
		
	}
	
	/**
	 * Determines if the files needs to be overwritten. 
	 * 
	 * @param directory The directory where the files will be stored.
	 * @param files The files to download.
	 * @return false if no file may be overwritten
	 */
	public boolean overwrite(File directory, DownloadFile[] files) {
		
		for (int i = 0; i < files.length; i++) {
			File existingFile = new File(directory, files[i].getFileName());
			
			if (existingFile.exists()) {
				
				int returnValue = 0;
				
				if (files.length > 1) {
					returnValue = applet.handleExistingFile(files[i], existingFile, true);
				} else {
					returnValue = applet.handleExistingFile(files[i], existingFile, false);
				}
				
				if (returnValue == ConfirmationDialog.CANCEL_OPTION) {
					return false;
				} else if (returnValue == ConfirmationDialog.NO_OPTION) {
					files[i].setOverwrite(false);
				} else if (returnValue == ConfirmationDialog.YES_TO_ALL_OPTION) {
					break;
				}
			}
		}
		
		return true;
		
	}
	
	/**
	 * Downloads a file.
	 * 
	 * @param directory The directory where the file will be stored.
	 * @param url The url of the file to be downloaded.
	 * @param fileName The name how the file will be stored.
	 * @param codebase The codebase of the applet.
	 */
	public void downloadFile(File directory, URL url, String fileName, URL codebase) {

		applet.addDestroyListener(this);
		File file = null;

		try {
			status = LocaleManager.getInstance().getString("downloading") + " ...";

			fileInRow++;

			// sets the file in progress
			fileInProgress = fileName;

			fileExist = false;

			// create the file with the local path
			file = new File(directory, fileName);

			if (file.exists()) {
				fileExist = true;
			}

			// retrieve the remote file
			conn = (HttpURLConnection) url.openConnection();
			conn.setRequestMethod("GET");
			
			// retrieve the cookies
			// cookies will be retrieve by the use of the java plugin
			// unfortunately this doesn't work in Opera.
			// For Opera the Javascript solution will work.
			String cookieHandler = null;
			
			if (System.getProperty("java.specification.version").equalsIgnoreCase("1.4")) {
				cookieHandler = "sun.plugin.net.cookie.PluginCookieManager";
			} else {
				cookieHandler = "com.sun.deploy.net.cookie.DeployCookieManager";
			}
			
			String cookie = null;
			
			try {
				Class clss = Class.forName(cookieHandler);
				Class[] parameterTypes = new Class[] {URL.class};
				Method meth = clss.getMethod("getCookieInfo", parameterTypes);	
				Object[] arguments = new Object[] {codebase};
				cookie = (String)meth.invoke(clss.newInstance(), arguments);
			} catch (Exception ex) {
				// do nothing
				// in Opera the classes cannot be found an exception will be thrown.
			}
			
			if (cookie != null && !cookie.trim().equalsIgnoreCase("")) {
				Logger.log("DownloadManager", "downloadFile()", "CookieInfo: " + cookie);
				conn.setRequestProperty("Cookie", cookie);
			}
			
			// cookies cannot be retrieve by the use of the java plugin 
			else {
				cookie = Parameters.getParameter(Parameters.COOKIE, null);
				
				if (cookie != null) {
					Logger.log("DownloadManager", "downloadFile()", "CookieInfo: " + cookie);
					conn.setRequestProperty("Cookie", cookie);					
				}
			}

			int responseCode = conn.getResponseCode();

			if (responseCode != 200) {

				if (responseCode == 404) {
					String message = LocaleManager.getInstance().getString("file_not_found");
					message = message.replaceAll("<filename>", file.getName());
					message += " cannot be found [response code: " + responseCode + "].";
					progressDialog.showMessage(message);
				} else {
					String message = LocaleManager.getInstance().getString("error_occurred_during_download");
					message = message.replaceAll("<filename>", file.getName());
					message += " [response code: " + responseCode + "].";
					progressDialog.showMessage(message);
				}

				return;

			} else {

				// log the responseCode
				Logger.log("DownloadManager", "downloadFile", "File: " + fileName + " " + "[Response code: " + String.valueOf(responseCode) + "]");
			}

			// set the bytes downloaded for a the specific file to 0
			bytesDownloaded = 0;

			in = conn.getInputStream();
			out = new FileOutputStream(file);

			String contentLength = conn.getHeaderField("Content-Length");

			// download based on the header contentlength
			if (contentLength != null) {
				bytes = Long.parseLong(contentLength);

				int size = Integer.parseInt(contentLength);

				int read = 0;
				byte[] b = new byte[1024];

				while ((read = in.read(b)) != -1) {

					totalBytesDownloaded += read;
					bytesDownloaded += read;

					size = size - read;

					if (size < 0) {
						out.write(b, 0, read - size);
					} else {
						out.write(b, 0, read);
					}
				}

				// download based on end -1
			} else {

				int read = 0;
				byte[] b = new byte[1024];

				while ((read = in.read(b)) != -1) {

					totalBytesDownloaded += read;
					bytesDownloaded += read;
					out.write(b, 0, read);
				}
			}

			out.flush();
			in.close();
			
			localFiles.add(file);

		} catch (Exception ex) {

			if (!cancel) {

				if (fileExist) {
					String message = LocaleManager.getInstance().getString("permission");
					message = message.replaceAll("<filename>", file.getName());
					progressDialog.showMessage(message);
				} else {
					String message = LocaleManager.getInstance().getString("error_occurred");
					message = message.replaceAll("<filename>", file.getName());
					progressDialog.showMessage(message);
				}

				Logger.log("DownloadManager", "downloadFile", "Error occurred with file: " + file.getName());
			}
			
		} finally {
			
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					// do nothing
				}
			}
			
			
			if (out != null) {
				try {
					out.close();
				} catch (IOException e) {
					// do nothing
				}
			}
			
			if (conn != null) {
				conn.disconnect();
			}
			
			applet.removeDestroyListener(this);
		}
	}
	
	/**
	 * Returns the elapsed time in ms.
	 * 
	 * @return The elapsed time ms.
	 */
	public synchronized int getElapsedTime() {

		return (int) (System.currentTimeMillis() - begin);
	}

	/**
	 * Cancels the download.
	 */
	public void cancel() {

		try {
			cancel = true;
			out.close();
		} catch (IOException ioe) {
			// do nothing
		}

	}

	/**
	 * Returns the percent completed.
	 * 
	 * @return The percent completed.
	 */
	public int getPercentCompleted() {

		return (int) (((double) bytesDownloaded / (double) bytes) * 100);
	}

	/**
	 * Returns the total bytes downloaded.
	 * 
	 * @return The total bytes downloaded.
	 */
	public synchronized long getTotalBytesDownloaded() {
		return totalBytesDownloaded;
	}

	/**
	 * Returns the number of file in the row of files to be downloaded.
	 * 
	 * @return The number.
	 */
	public synchronized int getFileInRow() {
		return fileInRow;
	}

	/**
	 * Returns the total number of files to be downloaded.
	 * 
	 * @return The total number of files to be downloaded.
	 */
	public synchronized int getNumberOfFiles() {
		return numberOfFiles;
	}

	/**
	 * Returns true if the download is finished.
	 * 
	 * @return True if the download is finished.
	 */
	public synchronized boolean isFinished() {
		return finished;
	}

	/**
	 * Returns the status.
	 * 
	 * @return The status.
	 */
	public synchronized String getStatus() {
		return status;
	}

	/**
	 * Returns the filename in progress.
	 * 
	 * @return The filename in progress.
	 */
	public synchronized String getFileInProgress() {
		return fileInProgress;
	}

	/**
	 * Shows the JavaAtWork dialog.
	 * 
	 * @return boolean True if the user wants to visit www.javaatwork.com
	 */
	private boolean showFreeDialog() {
		int returnValue = TimeOutOptionPane.showTimeoutDialog(applet);

		if (returnValue == TimeOutOptionPane.JAVAATWORK_OPTION) {

			try {

				applet.getAppletContext().showDocument(new URL("http://www.javaatwork.com"), "_blank");

				return true;
			} catch (MalformedURLException mue) {
				Logger.log("UploadActionListener", "actionPerformed", mue.toString());
			}
		}

		return false;
	}


	/**
	 * Closes the connections in case that the applet is destroyed.
	 */
	public void destroy() {
		
		if (in != null) {
			try {
				in.close();
			} catch (IOException e) {
				// do nothing
			}
		}
		
		
		if (out != null) {
			try {
				out.close();
			} catch (IOException e) {
				// do nothing
			}
		}
		
		if (conn != null) {
			conn.disconnect();
		}		
	}

}