使用AppLoader实现java应用程序更新。JAVA

Question

我有一个java swing应用程序，希望使用AppLoader进行自动更新。我在网上找到的java类

**https://reportmill.wordpress.com/2014/12/04/automatically-update-your-javapackager-applications/ **

有人有过这门课的经验吗。我似乎无法用我的应用程序实现该类，并且出现错误： JAVA木卫一。FileNotFoundException:C:\Users\home\Documents\NetBeansProjects\test\U update\build\classes（访问被拒绝）

及

爪哇。lang.RuntimeException:找不到主Jar

Answer 1

是的，代码似乎不起作用。我对代码做了一些修改以使其正常工作。请按以下步骤进行：

1. 通过http://reportmill.com/snap1/SnapCode1.jar.pack.gz下载文件
2. 将此文件复制到C:\Users\home\Documents\NetBeansProjects\test\u update\build\classes

3. 复制并粘贴下面的代码，然后运行它

   导入java。伊奥； 导入java。朗，反思一下。方法 导入java。网； 导入java。短信； 导入java。util。罐子； 导入javax。摇摆。*； 导入java。util。拉链GZIPInputStream

   /**
    * This app
    */
   
   public class AppLoader {
   
   // Constants
   static final String AppDirName = "SnapCode";
   static final String JarName = "SnapCode1.jar";
   static final String JarURL = "http://reportmill.com/snap1/SnapCode1.jar.pack.gz";
   static final String MainClass = "snap.app.App";
   
   /**
    * Main method - reinvokes main1() on Swing thread in exception handler.
    */
   public static void main(final String args[]) {
       // Invoke real main with exception handler
       try {
           main1(args);
       } catch (Throwable e) {
           JOptionPane.showMessageDialog(null, e.toString());
           e.printStackTrace();
       }
   }
   
   /**
    * Main method: - Gets main Jar file from default, if missing - Updates main
    * Jar file from local update file, if previously loaded - Load main Jar
    * into URLClassLoader, load main class and invoke main method - Check for
    * update from remove site in background
    */
   public static void main1(final String args[]) throws Exception {
       // Make sure default jar is in place
       try {
           copyDefaultMainJar();
       } catch (Exception e) {
           JOptionPane.showMessageDialog(null, e.toString());
           e.printStackTrace();
       }
   
       // If Update Jar exists, copy it into place
       File jar = getAppFile(JarName);
       File updateJar = getAppFile(JarName + ".update");
       if (updateJar.exists()) {
           copyFile(updateJar, jar);
           jar.setLastModified(updateJar.lastModified());
           updateJar.delete();
       }
   
       // If jar doesn't exist complain bitterly
       if (!jar.exists() || !jar.canRead())
           throw new RuntimeException("Main Jar not found!");
   
       // Check for updates in background thread
       if (args.length == 0 || !args[0].equals("-snap"))
           new Thread(new Runnable() {
               public void run() {
                   checkForUpdatesSilent();
               }
           }).start();
   
       // Create URLClassLoader for main jar file, get App class and invoke
       // main
   //      URLClassLoader ucl = new URLClassLoader(
   //              new URL[] { jar.toURI().toURL() });
   //      Class cls = ucl.loadClass(MainClass); // ucl.close();
   //      Method meth = cls.getMethod("main", new Class[] { String[].class });
   //      meth.invoke(null, new Object[] { args });
   //      if (cls == Object.class)
   //          ((Closeable) ucl).close(); // Getting rid of warning message for ucl
   }
   
   /**
    * Copies the default main jar into place for initial run.
    */
   private static void copyDefaultMainJar() throws IOException, ParseException {
       // Get main jar from app package and get location of working jar file
       URL url = AppLoader.class.getProtectionDomain().getCodeSource()
               .getLocation();
       String path0 = url.getPath();
       path0 = URLDecoder.decode(path0, "UTF-8");
   
       path0 = path0 + "SnapCode1.jar.pack.gz" ;
       File jar0 = getAppFile(JarName);
       File jar1 = new File(path0);
   
       // If app package main jar is newer, copy it into place and set time
       if (jar0.exists() && jar0.lastModified() >= jar1.lastModified())
           return;
       copyFile(jar1, jar0);
   }
   
   /**
    * Check for updates.
    */
   private static void checkForUpdatesSilent() {
       try {
           checkForUpdates();
       } catch (Exception e) {
           e.printStackTrace();
       }
   }
   
   /**
    * Check for updates.
    */
   private static void checkForUpdates() throws IOException,
           MalformedURLException {
       // Get URL connection and lastModified time
       File jarFile = getAppFile(JarName);
       URL url = new URL(JarURL);
       URLConnection connection = url.openConnection();
       long mod0 = jarFile.lastModified(), mod1 = connection.getLastModified();
       if (mod0 >= mod1) {
           System.out.println("No update available at " + JarURL + '(' + mod0
                   + '>' + mod1 + ')');
           return;
       }
   
       // Get update file and write to JarName.update
       System.out.println("Loading update from " + JarURL);
       byte bytes[] = getBytes(connection);
       System.out.println("Update loaded");
       File updatePacked = getAppFile(JarName + ".pack.gz"), updateFile = getAppFile(JarName
               + ".update");
       writeBytes(updatePacked, bytes);
       System.out.println("Update saved: " + updatePacked);
       unpack(updatePacked, updateFile);
       System.out.println("Update unpacked: " + updateFile);
       updateFile.setLastModified(mod1);
       updatePacked.delete();
   
       // Let the user know
       SwingUtilities.invokeLater(new Runnable() {
           public void run() {
               JOptionPane
                       .showMessageDialog(null,
                               "A new update is available. Restart application to apply");
           }
       });
   }
   
   /**
    * Returns the Main jar file.
    */
   private static File getAppFile(String aName) {
       return new File(getAppDir(), aName);
   }
   
   /**
    * Returns the Main jar file.
    */
   private static File getAppDir() {
       return getAppDataDir(AppDirName, true);
   }
   
   /**
    * 
    * Utility Methods for AppLoader.
    * 
    */
   
   /**
    * Copies a file from one location to another.
    */
   public static File copyFile(File aSource, File aDest) throws IOException {
       // Get input stream, output file and output stream
       FileInputStream fis = new FileInputStream(aSource);
       File out = aDest.isDirectory() ? new File(aDest, aSource.getName())
               : aDest;
       FileOutputStream fos = new FileOutputStream(out);
   
       // Iterate over read/write until all bytes written
       byte[] buf = new byte[8192];
       for (int i = fis.read(buf); i != -1; i = fis.read(buf))
           fos.write(buf, 0, i);
   
       // Close in/out streams and return out file
       fis.close();
       fos.close();
       return out;
   }
   
   /**
    * Writes the given bytes (within the specified range) to the given file.
    */
   public static void writeBytes(File aFile, byte theBytes[])
           throws IOException {
       if (theBytes == null) {
           aFile.delete();
           return;
       }
       FileOutputStream fileStream = new FileOutputStream(aFile);
       fileStream.write(theBytes);
       fileStream.close();
   }
   
   /**
    * Unpacks the given file into the destination file.
    */
   public static File unpack(File aFile, File aDestFile) throws IOException {
       // Get dest file - if already unpacked, return
       File destFile = getUnpackDestination(aFile, aDestFile);
       if (destFile.exists() && destFile.lastModified() > aFile.lastModified())
           return destFile;
   
       // Create streams: FileInputStream -> GZIPInputStream -> JarOutputStream
       // -> FileOutputStream
       FileInputStream fileInput = new FileInputStream(aFile);
       GZIPInputStream gzipInput = new GZIPInputStream(fileInput);
       FileOutputStream fileOut = new FileOutputStream(destFile);
       JarOutputStream jarOut = new JarOutputStream(fileOut);
   
       // Unpack file
       Pack200.newUnpacker().unpack(gzipInput, jarOut);
   
       // Close streams
       fileInput.close();
       gzipInput.close();
       jarOut.close();
       fileOut.close();
   
       // Return destination file
       return destFile;
   }
   
   /**
    * Returns the file that given packed file would be saved to using the
    * unpack method.
    */
   public static File getUnpackDestination(File aFile, File aDestFile) {
       // Get dest file - if null, create from packed file minus .pack.gz
       File destFile = aDestFile;
       if (destFile == null)
           destFile = new File(aFile.getPath().replace(".pack.gz", ""));
   
       // If dest file is directory, change to file inside with packed file
       // minus .pack.gz
       else if (destFile.isDirectory())
           destFile = new File(destFile, aFile.getName().replace(".pack.gz",
                   ""));
   
       // Return destination file
       return destFile;
   }
   
   /**
    * Returns the AppData or Application Support directory file.
    */
   public static File getAppDataDir(String aName, boolean doCreate) {
       // Get user home + AppDataDir (platform specific) + name (if provided)
       String dir = System.getProperty("user.home");
       if (isWindows)
           dir += File.separator + "AppData" + File.separator + "Local";
       else if (isMac)
           dir += File.separator + "Library" + File.separator
                   + "Application Support";
       if (aName != null)
           dir += File.separator + aName;
   
       // Create file, actual directory (if requested) and return
       File dfile = new File(dir);
       if (doCreate && aName != null)
           dfile.mkdirs();
       return dfile;
   }
   
   /**
    * Returns bytes for connection.
    */
   public static byte[] getBytes(URLConnection aConnection) throws IOException {
       InputStream stream = aConnection.getInputStream(); // Get stream for
                                                           // connection
       byte bytes[] = getBytes(stream); // Get bytes for stream
       stream.close(); // Close stream
       return bytes; // Return bytes
   }
   
   /**
    * Returns bytes for an input stream.
    */
   public static byte[] getBytes(InputStream aStream) throws IOException {
       ByteArrayOutputStream bs = new ByteArrayOutputStream();
       byte chunk[] = new byte[8192];
       for (int len = aStream.read(chunk, 0, 8192); len > 0; len = aStream
               .read(chunk, 0, 8192))
           bs.write(chunk, 0, len);
       return bs.toByteArray();
   }
   
   // Whether Windows/Mac
   static boolean isWindows = (System.getProperty("os.name")
           .indexOf("Windows") >= 0);
   static boolean isMac = (System.getProperty("os.name").indexOf("Mac OS X") >= 0);
   

   }

您的问题是，在copyFile方法中，FileInputStream获取了错误的文件对象