// Jay Summet, Georgia Tech
// CS 1316, Summer 2009
//
//Demonstrates writing to files using the GZIP stream and then
// reading GZIPed data back. It also illustrates using object 
// "chaining" where multiple stream handling objects pass data
// on to the next object to transform it multiple ways.



import java.io.*;
import java.util.zip.*;


public class GZIPdemo {
  
  
  private static final String ourString = 
    "The Romane without doubte, and I will tell the commoditie, and" +
"the discommoditie of the one, and the other. The Dutche footemen, are"+
"able to withstande, and overcome the horses: they bee moste speedie to"+
"marche, and to be set in araye, being not laden with armours: of the"+
"other part, they be subjecte to all blowes, both farre of, and at hande:"+
"because they be unarmed, they bee unprofitable unto the battaile on the"+
"lande, and to everye fighte, where is strong resistaunce. But the"+
"Romanes withstoode, and overcame the horses, as well as the Dutchemen,"+
"they were safe from blowes at hande, and farre of, being covered with"+
"armours: they were also better able to charge, and better able to"+
"sustaine charges, having Targaettes: they might more aptly in the preace"+
"fight with the swoorde, then these with the Pike, and though the"+
"Dutchemen have likewise swoordes, yet being without Targaets, they"+
"become in suche case unprofitable: The Romanes might safelye assaul't"+
"townes, having their bodies cleane covered with armour, and being better"+
"able to cover themselves with their Targaettes. So that they had no"+
"other incommoditie, then the waightynesse of their armours, and the pain"+
"to cary them: the whiche thinges thei overcame, with accustomyng the"+
"body to diseases, and with hardenyng it, to bee able to indure labour."+
"And you knowe, how that in thinges accustomed, men suffer no grief. And"+
"you have to understand this, that the footemen maie be constrained, to"+
"faight with footemen, and with horse, and alwaies those be unprofitable,"+
"whiche cannot either sustain the horses, or beyng able to sustain them,"+
"have notwithstandyng neede to feare the footemen, whiche be better"+
"armed, and better ordeined then thei. Now if you consider the Duchemen,"+
"and the Romaines, you shall finde in the Duchemen activitie (as we have"+
"said) to overcome the horses, but greate dissavauntage, when thei"+
"faighte with menne, ordeined as thei them selves are, and armed as the"+
"Romaines were: so that there shall be this advauntage more of the one,"+
"then of thother, that the Romaines could overcome the men, and the"+
"horses, the Duchemen onely the horses.";
  
  
  // Writes a string (Characters) to an outputStreamWriter, which converts
  // the characters to bytes that are written out the FileOutputStream.
  public void write(String filename) {
    try {
        // The file object.
        File f = new File(filename);
        
        // File output streams write to a file....
        FileOutputStream fos = new FileOutputStream(f);
        
        //OutputStreamWriter converts charactrs in strings to bytes.
        OutputStreamWriter osw = new OutputStreamWriter(fos);
        
        // write out a bit of text
        osw.write( ourString);
        osw.close();
        } catch (Exception e) {
      System.out.println("Exception happened! " + e.getMessage());
      
    }
  }
  
  // Writes a string (Characters) to an outputStreamWriter, which converts
  // the characters to bytes that are written out to the GZIPOutputStream
  // the compresses the string before sending it to the FileOutputStream.
  public  void GZIPwrite( String filename) {
    try {
      
      // Make a OutputWriterStream -> GZIPOutputStream -> FileOutputStream -> File  stream...
      File f = new File(filename);
      
      // Writes the bytes to the file.
      FileOutputStream fos = new FileOutputStream( f) ;
      
      // GZIP's the bytes as they come out of the Output Stream Writer
      GZIPOutputStream gos = new GZIPOutputStream( fos );
      
      // Converts characters to bytes
      OutputStreamWriter osw = new OutputStreamWriter( gos);
      
      
      // Write a bit of text...
      osw.write( ourString);
      osw.close();
    } catch (Exception e) {
      
      System.out.println("Exception happened! " + e.getMessage());
    }
    
    
  } // end write()
  
  
  public void GZIPread( String filename) {
     try {
      
      // Make File -> FileInputStream -> GZIPInputStream -> InputStreamReader -> BufferedReader
  
      File f = new File(filename);
      // Reads (compressed) bytes from the file.
      FileInputStream fis = new FileInputStream( f) ;
      
      // Uncompresses the compressed bytes
      GZIPInputStream gis = new GZIPInputStream( fis );
      
      // Converts the bytes to characters.
      InputStreamReader isr = new InputStreamReader( gis);
      
      // Buffers up a line at a time, allowing you to read a full line at once.
      BufferedReader reader = new BufferedReader(isr);
      
        
        String line = null;
      
      // Read in the text!
      while( (line = reader.readLine()) != null) {
        System.out.println(line + "\n");
      }
      
      reader.close();
    } catch (Exception e) {
      
      System.out.println("Exception happened! " + e.getMessage());
    }
    
  } // end read()
  
  public  static void main( String[] args) {
    
    GZIPdemo gzd = new GZIPdemo();
    
    gzd.write("output.txt");
    gzd.GZIPwrite( "output.gzip");
    // Just to prove we can read in the compressed text file:
    System.out.println("compressed file contents:\n");
    gzd.GZIPread( "output.gzip");
    
  }
  
}