JavaZip Inflater.needsDictionary() 方法

package com.codingdict;



import java.io.UnsupportedEncodingException;

import java.util.zip.DataFormatException;

import java.util.zip.Deflater;

import java.util.zip.Inflater;



public class InflaterDemo {

   public static void main(String[] args) 

      throws DataFormatException, UnsupportedEncodingException {

      String message = "Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;"

         +"Welcome to codingdict.com;";

      String dictionary = "Welcome";



      System.out.println("Original Message length : " + message.length());

      byte[] input = message.getBytes("UTF-8");



      // Compress the bytes

      byte[] output = new byte[1024];

      Deflater deflater = new Deflater();

 deflater.setDictionary(dictionary.getBytes("UTF-8"));

      deflater.setInput(input);



      deflater.finish();

      int compressedDataLength = deflater.deflate(output,0 , output.length, Deflater.NO_FLUSH);

      System.out.println("Total uncompressed bytes output :" + deflater.getTotalOut());

      System.out.println("Compressed Message Checksum :" + deflater.getAdler());     

      deflater.finished();



      System.out.println("Compressed Message length : " + compressedDataLength);



      // Decompress the bytes

      Inflater inflater = new Inflater();

      inflater.setInput(output, 0, compressedDataLength);

      byte[] result = new byte[1024];

      int resultLength = inflater.inflate(result);

      if(inflater.needsDictionary()){



         inflater.setDictionary(dictionary.getBytes("UTF-8"));



         resultLength = inflater.inflate(result);

      }

      inflater.finished();



      // Decode the bytes into a String

      message = new String(result, 0, resultLength, "UTF-8");

      System.out.println("UnCompressed Message Checksum :" + inflater.getAdler());  

      System.out.println("UnCompressed Message length : " + message.length());

   }

}