downloader.java

Java游戏高级编程！！很不错的！！！Java游戏高级编程！！很不错的

     package com.croftsoft.core.net;

     import java.io.*;
     import java.net.*;
     import java.util.*;

     import com.croftsoft.core.lang.StringLib;

     /*********************************************************************
     * Downloads the content of a URL to a local File.
     * 
     * <p />
     *
     * @version
     *   2003-11-06
     * @since
     *   1998-11-30
     * @author
     *   <a href="http://www.croftsoft.com/">David Wallace Croft</a>
     *********************************************************************/

     public final class  Downloader
     //////////////////////////////////////////////////////////////////////
     //////////////////////////////////////////////////////////////////////
     {

     /*********************************************************************
     * Downloads files.
     *
     * <pre>
     * if ( args.length < 4 )
     * {
     *   validate ( args [ 0 ], args [ 1 ], true, true );
     * }
     * else
     * {
     *   download ( args [ 0 ], args [ 1 ],
     *     Integer.parseInt ( args [ 2 ] ),
     *     Integer.parseInt ( args [ 3 ] ) );
     * }
     * </pre>
     *********************************************************************/
     public static void  main ( String [ ]  args )
       throws Exception
     //////////////////////////////////////////////////////////////////////
     {
       if ( args.length < 4 )
       {
         validate ( args [ 0 ], args [ 1 ], true, true );
       }
       else
       {
         download ( args [ 0 ], args [ 1 ],
           Integer.parseInt ( args [ 2 ] ),
           Integer.parseInt ( args [ 3 ] ) );
       }
     }

     //////////////////////////////////////////////////////////////////////
     //////////////////////////////////////////////////////////////////////

     /*********************************************************************
     * Downloads a sequence of files ending in a number.
     *********************************************************************/
     public static void  download (
       String  urlPrefix,
       String  filenamePrefix,
       int     start,
       int     stop )
       throws IOException
     //////////////////////////////////////////////////////////////////////
     {
       for ( int  index = start; index <= stop; index++ )
       {
         String  url = urlPrefix + index;

         String  filename = filenamePrefix + index;

         System.out.println (
           "Downloading " + url + " to " + filename + "..." );

         download ( url, filename );
       }       
     }

     public static void  download (
       String  urlString,
       String  filename )
       throws IOException, MalformedURLException
     //////////////////////////////////////////////////////////////////////
     {
       download ( new URL ( urlString ), new File ( filename ) );
     }

     /*********************************************************************
     * Downloads the content at a URL to a local destination File.
     *********************************************************************/
     public static void  download ( URL  url, File  dest )
       throws IOException
     //////////////////////////////////////////////////////////////////////
     {
       download ( url.openStream ( ), dest );
     }

     public static void  download (
       InputStream  unbufferedInputStream,
       File         destinationFile )
       throws IOException
     //////////////////////////////////////////////////////////////////////
     {
       BufferedInputStream   in  = null;

       BufferedOutputStream  out = null;

       try
       {
         in  = new BufferedInputStream ( unbufferedInputStream );

         out = new BufferedOutputStream (
           new FileOutputStream ( destinationFile ) );

         int  i;

         while ( ( i = in.read ( ) ) > -1 )
         {
           out.write ( ( byte ) i );
         }
       }
       finally
       {
         if ( out != null )
         {
           out.close ( );
         }

         if ( in != null )
         {
           in.close ( );
         }
       }
     }

     public static boolean  downloadResourceToDir (
       URL  codebaseURL, String  name, File  destDir )
     //////////////////////////////////////////////////////////////////////
     {
       if ( ( codebaseURL == null )
         || ( name        == null )
         || ( destDir     == null ) )
//       || !destDir.exists ( )
//       || !destDir.isDirectory ( ) )
         return false;

       InputStream           inputStream = null;
       BufferedInputStream   in          = null;
       BufferedOutputStream  out         = null;

       try
       {
         // We create the file twice to make sure the path is resolved.
//System.out.println ( "destDir:  " + destDir.getCanonicalPath ( ) );
//System.out.println ( "name:  " + name );
         File  cacheFile = new File ( destDir, name );
//System.out.println ( "cacheFile1:  " + cacheFile.getCanonicalPath ( ) );
         cacheFile = new File ( cacheFile.getCanonicalPath ( ) );
//System.out.println ( "cacheFile2:  " + cacheFile.getCanonicalPath ( ) );

         File  parentFile = new File ( cacheFile.getParent ( ) );
//System.out.println ( "parentFile:  " + parentFile.getCanonicalPath ( ) );
//System.out.println ( "mkdirs:  " + parentFile.mkdirs ( ) );
         parentFile.mkdirs ( );

         inputStream = downloadResource ( codebaseURL, name );
         if ( inputStream == null )
         {
           System.out.println ( "  Download of \"" + name + "\" from\n"
             + "    \"" + codebaseURL + "\" failed." );
           return false;
         }

         in  = new BufferedInputStream ( inputStream );
         out = new BufferedOutputStream (
           new FileOutputStream ( cacheFile ) );

         int  i;
         while ( ( i = in.read ( ) ) > -1 ) out.write ( ( byte ) i );

System.out.println ( "  Successfully downloaded and saved." );

         return true;
       }
       catch ( Exception  ex )
       {
         ex.printStackTrace ( );
       }
       finally
       {
         try { out.close          ( ); } catch ( Exception  ex1 ) { }
         try { in.close           ( ); } catch ( Exception  ex1 ) { }
         try { inputStream.close  ( ); } catch ( Exception  ex1 ) { }
       }

       return false;
     }

     /*********************************************************************
     * Returns null if the codebaseURL is null.
     * Returns null upon failure.
     *********************************************************************/
     public static InputStream  downloadResource (
       URL  codebaseURL, String  name )
     //////////////////////////////////////////////////////////////////////
     {
       if ( codebaseURL == null ) return null;

       InputStream  inputStream = null;
       
       try
       {
         String  urlName
           = replaceSpaces ( replaceSeparators ( name ) );

         URL  url = new URL ( codebaseURL, urlName );
System.out.println ( "Downloading \"" + name + "\" from\n  \"" + url + "\"" );

         URLConnection  urlConnection = url.openConnection ( );

         inputStream = urlConnection.getInputStream ( );

         return inputStream;
       }
       catch ( IOException  ex )
       {
         try { inputStream.close ( ); } catch ( Exception  ex1 ) { }
         return null;
       }
     }

     /*********************************************************************
     * Determines if the local file is valid.
     *
     * <p>
     * If both <i>compareContentLength</i> and <i>compareLastModified</i>
     * are false, this methods simply checks for the existence of the
     * local file.
     * </p>
     *********************************************************************/
     public static boolean  isValid (
       URL      sourceURL,
       File     localFile,
       boolean  compareContentLength,
       boolean  compareLastModified )
       throws IOException, ProtocolException
     //////////////////////////////////////////////////////////////////////
     {
       if ( !localFile.exists ( ) )
       {
         return false;
       }

       if ( !compareContentLength && !compareLastModified )
       {
         return true;
       }

       URLConnection  urlConnection = sourceURL.openConnection ( );

       if ( compareContentLength )
       {
         long  localLength = localFile.length ( );

//       System.out.println ( "localLength:  " + localLength );

// What if this is greater than Integer.MAX_VALUE?

         int  sourceLength = urlConnection.getContentLength ( );

//       System.out.println ( "sourceLength:  " + sourceLength );

         if ( localLength != sourceLength )
         {
           return false;
         }
       }

       if ( compareLastModified )
       {
         long  localLastModified = localFile.lastModified ( );

         //System.out.println (
         //  "localLastModified:  " + new Date ( localLastModified ) );

         long  sourceLastModified = urlConnection.getLastModified ( );

         //System.out.println (
         //  "sourceLastModified:  " + new Date ( sourceLastModified ) );

         if ( localLastModified != sourceLastModified )
         {
           return false;
         }
       }

       return true;
     }

     /*********************************************************************
     * Determines if the local file is valid.
     *
     * <p>
     * If both <i>compareContentLength</i> and <i>compareLastModified</i>
     * are false, this methods simply checks for the existence of the
     * local file.
     * </p>
     *
     * @param  sourceURLName
     *
     *   An HTTP URL.
     *********************************************************************/
     public static boolean  isValid (
       String   sourceURLName,
       String   localFilename,
       boolean  compareContentLength,
       boolean  compareLastModified )
       throws IOException, ProtocolException
     //////////////////////////////////////////////////////////////////////
     {
       return isValid (
         new URL  ( sourceURLName ),
         new File ( localFilename ),
         compareContentLength,
         compareLastModified );
     }

     /*********************************************************************
     * Replaces every instance of File.separator with a forward slash
     * character.  This is used for converting a local path name to
     * a URL path name.
     *********************************************************************/
     public static String  replaceSeparators ( String  localPath )
     //////////////////////////////////////////////////////////////////////
     {
       return StringLib.replace ( localPath, File.separator, "/" );
     }

     /*********************************************************************
     * Replaces every instance of space (" ") with the
     * x-www-form-urlencoded equivalent ("%20").
     * This is used for converting a remote filename with spaces so that
     * it can be downloaded via a HTTP request.
     *********************************************************************/
     public static String  replaceSpaces ( String  remoteFilename )
     //////////////////////////////////////////////////////////////////////
     {
       return StringLib.replace ( remoteFilename, " ", "%20" );
     }

     /*********************************************************************
     * Downloads a file if the local copy is missing or outdated.
     *
     * @return
     *
     *   True if a new copy needed to be downloaded.
     *********************************************************************/
     public static boolean  validate (
       String   sourceURLName,
       String   localFilename,
       boolean  checkContentLength,
       boolean  checkLastModified )
       throws IOException, MalformedURLException
     //////////////////////////////////////////////////////////////////////
     {
       return validate (
         new URL  ( sourceURLName ),
         new File ( localFilename ),
         checkContentLength,
         checkLastModified );
     }

     /*********************************************************************
     * Downloads a file if the local copy is missing or outdated.
     *
     * @return
     *
     *   True if a new copy needed to be downloaded.
     *********************************************************************/
     public static boolean  validate (
       URL      sourceURL,
       File     localFile,
       boolean  checkContentLength,
       boolean  checkLastModified )
       throws IOException
     //////////////////////////////////////////////////////////////////////
     {
       if ( !localFile.exists ( ) )
       {
         Downloader.download ( sourceURL, localFile );

         return true;
       }
       else if ( checkContentLength || checkLastModified )
       {
         long  localLength = localFile.length ( );

         //System.out.println ( "localLength:  " + localLength );

         long  localLastModified = localFile.lastModified ( );

         //System.out.println (
         //  "localLastModified:  " + new Date ( localLastModified ) );

         URLConnection  urlConnection = sourceURL.openConnection ( );

         int  sourceLength = urlConnection.getContentLength ( );

         //System.out.println ( "sourceLength:  " + sourceLength );

         long  sourceLastModified = urlConnection.getLastModified ( );

         //System.out.println ( "sourceLastModified:  "
         //  + new Date ( sourceLastModified ) );

         InputStream  inputStream = null;

         try
         {
           inputStream = urlConnection.getInputStream ( );

           if ( checkContentLength
                  && ( sourceLength != localLength )
             || checkLastModified
                  && ( sourceLastModified > localLastModified ) )
           {
             //System.out.println ( "Downloading \"" + sourceURL
             //  + "\" to \"" + localFile + "\"..." );

             download ( inputStream, localFile );

             return true;
           }
         }
         finally
         {
           if ( inputStream != null )
           {
             inputStream.close ( );
           }
         }
       }

       return false;
     }
     
     //////////////////////////////////////////////////////////////////////
     //////////////////////////////////////////////////////////////////////

     private  Downloader ( ) { }

     //////////////////////////////////////////////////////////////////////
     //////////////////////////////////////////////////////////////////////
     }