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Convenience class for working with Gzip text files.

/ Published in: Java
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I wrote this for an enterprise level event logging cluster that has more traffic than Oprah. Has worked great for years of uptime... wish java had a decent bz2 implementation though.

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  1. import java.io.*;
  2. import java.util.zip.GZIPInputStream;
  3. import java.util.zip.GZIPOutputStream;
  4. import java.util.Random;
  5. import java.nio.channels.FileChannel;
  6. import java.nio.channels.FileLock;
  7. import java.nio.channels.OverlappingFileLockException;
  8. public class GZ implements Serializable {
  9.     private boolean makeDirectories(final String path){
  10.         boolean result;
  11.         try{
  12.             (new File(path).getParentFile()).mkdirs();
  13.             result=true;
  14.         }catch(Exception e){
  15.             result=false;
  16.             e.printStackTrace();
  17.         }
  18.         return result;
  19.     }
  20.     private String getParent(final String path){
  21.         StringBuilder result = new StringBuilder();
  22.         try{
  23.             result.append(new File(path).getParent());
  24.             if(!result.toString().endsWith("/")){result.append("/");}
  25.         }catch(Exception e){ e.printStackTrace(); }
  26.         return result.toString();
  27.     }
  28.     public StringBuilder readTextFile(final String filename){
  29.         StringBuilder sb = new StringBuilder();
  30.         FileInputStream fin = null;
  31.         GZIPInputStream gzis = null;
  32.         InputStreamReader xover = null;
  33.         BufferedReader is = null;
  34.         FileChannel channel = null;
  35.         try{
  36.             File file = new File(filename);
  37.             if(file.exists()){
  38.                 channel = new RandomAccessFile(file, "rw").getChannel();
  39.                 FileLock lock = null;
  40.                 int attempt = 0;
  41.                 while (lock==null && attempt < 5){
  42.                     if(attempt > 0 ){Thread.sleep(1000);}
  43.                     try{lock=channel.tryLock();}catch(OverlappingFileLockException ofe){}
  44.                     attempt++;
  45.                 }
  46.                 if(lock !=null){
  47.                     fin = new FileInputStream(file);
  48.                     gzis = new GZIPInputStream(fin);
  49.                     xover = new InputStreamReader(gzis);
  50.                     is = new BufferedReader(xover);
  51.                     String line;
  52.                     while ((line = is.readLine( )) != null)sb.append(line).append("\n");
  53.                     lock.release();
  54.                 }
  55.             }
  56.         }catch(EOFException e){
  57.             System.out.println(new StringBuilder("EOF: (probably minor) ").append(filename).toString());
  58.             e.printStackTrace();
  59.         }catch(Exception e){
  60.             System.out.println(new StringBuilder("Bug GZ.readTextFile(): ").append(filename).toString());
  61.             e.printStackTrace();
  62.         }finally{
  63.             if(channel!=null){try{channel.close();}catch(Exception e){}}
  64.             if(is!=null){try{is.close();}catch(Exception e){}}
  65.             if(xover!=null){try{xover.close();}catch(Exception e){}}
  66.             if(gzis!=null){try{gzis.close();}catch(Exception e){}}
  67.             if(fin!=null){try{fin.close();}catch(Exception e){}}
  68.         }
  69.         return sb;
  70.     }
  71.     public boolean writeTextFile(final String filename,final StringBuilder content){
  72.         boolean result=false;
  73.         FileChannel channel=null;
  74.         GZIPOutputStream out=null;
  75.         makeDirectories(filename);
  76.         try {channel=new RandomAccessFile(filename,"rw").getChannel();
  77.             FileLock lock = null;
  78.             int attempt = 0;
  79.             while (lock==null && attempt < 5){
  80.                 if(attempt > 0 ){Thread.sleep(1000);}
  81.                 try{lock=channel.tryLock();}catch(OverlappingFileLockException ofe){}
  82.                 attempt++;
  83.             }
  84.             if(lock !=null){
  85.                 out=new GZIPOutputStream(new FileOutputStream(filename));
  86.                 out.write(content.toString().getBytes());
  87.                 lock.release();
  88.                 result=true;
  89.             }
  90.         }catch(Exception e){
  91.             System.out.println(new StringBuilder("Bug GZ.writeTextFile(): ").append(filename).toString());
  92.             e.printStackTrace();
  93.         }finally{
  94.             try{if(channel!=null){channel.close();}}catch(Exception e){}
  95.             try{if(out!=null){out.close();}}catch(Exception e){}
  96.         }
  97.         return result;
  98.     }
  99.     public boolean appendTextfile(final String filename,final StringBuilder content){
  100.         boolean result=false;
  101.         FileInputStream readIn = null;
  102.         GZIPInputStream readGZ = null;
  103.         InputStreamReader readISR = null;
  104.         BufferedReader readBR = null;
  105.         FileChannel readChannel = null;
  106.         FileChannel tempChannel=null;
  107.         GZIPOutputStream tempGZ=null;
  108.         Random r = new Random();
  109.         FileLock readLock=null;
  110.         FileLock tempLock=null;
  111.         // USE TEMP FILE
  112.         makeDirectories(filename);
  113.         String tempname = new StringBuilder(getParent(filename)).append("temp_").append(r.nextInt(9999999)).toString();
  114.         File readFile=new File(filename);
  115.         File tempFile=new File(tempname);
  116.         try{
  117.             tempChannel=new RandomAccessFile(tempFile,"rw").getChannel();
  118.             int attempt=0;
  119.             while(tempLock==null&&attempt<5){if(attempt>0){Thread.sleep(1000);}try{tempLock=tempChannel.tryLock();}catch(OverlappingFileLockException ofe){attempt++;}}
  120.             if(tempLock!=null){tempGZ=new GZIPOutputStream(new FileOutputStream(tempFile));}
  121.             // COPY PREVIOUS RECORDS TO TEMP FILE
  122.             if(readFile.exists()){
  123.                 readChannel=new RandomAccessFile(readFile, "rw").getChannel();
  124.                 int attemptA=0;
  125.                 while(readLock==null&&attemptA<5){
  126.                     if(attemptA>0){Thread.sleep(1000);}
  127.                     try{readLock=readChannel.tryLock();}catch(OverlappingFileLockException ofe){}
  128.                     attemptA++;
  129.                 }
  130.                 if(readLock!=null){
  131.                     readIn=new FileInputStream(readFile);
  132.                     readGZ=new GZIPInputStream(readIn);
  133.                     readISR=new InputStreamReader(readGZ);
  134.                     readBR=new BufferedReader(readISR);
  135.                     String line;
  136.                     while((line=readBR.readLine())!=null){if(tempLock!=null)tempGZ.write(new StringBuilder(line.trim()).append("\n").toString().getBytes());}
  137.                 }
  138.             }
  139.             // WRITE NEW DATA TO TEMPFILE
  140.             if(tempLock!=null){
  141.                 if(content.charAt(content.length()-1)!='\n'){content.append("\n");}
  142.                 tempGZ.write(content.toString().getBytes());
  143.                 tempGZ.finish();
  144.                 tempGZ.close();
  145.             }
  146.             // RENAME THE TEMP FILE TO THE OLDFILE
  147.             boolean success = tempFile.renameTo(readFile);
  148.             if(success){tempFile.delete();result=true;}else{System.out.println("HUGE PROBLEM... could not rename file:" + readFile.getAbsolutePath());result=false;}
  149.             // RELEASE THE FILE LOCKS
  150.             if(tempLock!=null){tempLock.release();}
  151.             if(readLock!=null){readLock.release();}
  152.         }catch(EOFException e){System.out.println(new StringBuilder("EOF: (probably minor) ").append(filename).toString());e.printStackTrace();
  153.         }catch(Exception e){System.out.println(new StringBuilder("Bug GZ.appendTextFile(): ").append(filename).toString());e.printStackTrace();
  154.         }finally{
  155.             if(readChannel!=null){try{readChannel.close();}catch(Exception e){}}
  156.             if(readIn!=null){try{readIn.close();}catch(Exception e){}}
  157.             if(readISR!=null){try{readISR.close();}catch(Exception e){}}
  158.             if(readGZ!=null){try{readGZ.close();}catch(Exception e){}}
  159.             if(readBR!=null){try{readBR.close();}catch(Exception e){}}
  160.             if(tempChannel!=null){try{tempChannel.close();}catch(Exception e){}}
  161.             if(tempGZ!=null){try{tempGZ.close();}catch(Exception e){}}
  162.         }
  163.         return result;
  164.     }
  165.     public void renameFile(final String old_name,final String new_name){
  166.         File f = new File(old_name);
  167.         f.renameTo(new File(new_name));
  168.     }
  169.     public boolean prependTextFile(final String filename,final StringBuilder content){
  170.         boolean result=false;
  171.         StringBuilder previous = null;
  172.         try{ previous = readTextFile(filename);}catch(Exception e){/* Did not previously exist */}
  173.         FileChannel channel=null;
  174.         GZIPOutputStream out=null;
  175.         makeDirectories(filename);
  176.         try {channel=new RandomAccessFile(filename,"rw").getChannel();
  177.             FileLock lock = null;
  178.             int attempt = 0;
  179.             while (lock==null && attempt < 5){
  180.                 if(attempt > 0 ){Thread.sleep(1000);}
  181.                 try{lock=channel.tryLock();}catch(OverlappingFileLockException ofe){}
  182.                 attempt++;
  183.             }
  184.             if(lock !=null){
  185.                 out=new GZIPOutputStream(new FileOutputStream(filename));
  186.                 out.write(content.toString().getBytes());
  187.                 if(previous!=null){out.write(previous.toString().getBytes());}
  188.                 lock.release();
  189.                 result=true;
  190.             }
  191.         }catch(Exception e){
  192.             System.out.println(new StringBuilder("Bug GZ.prependTextFile(): ").append(filename).toString());
  193.             e.printStackTrace();
  194.         }
  195.         finally{
  196.             try{if(channel!=null){channel.close();}}catch(Exception e){}
  197.             try{if(out!=null){out.close();}}catch(Exception e){}
  198.         }
  199.         return result;
  200.     }
  201. }

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