CompressionTools.java

package com.vanco.abplayer.util;

import java.util.zip.Deflater;
import java.util.zip.Inflater;
import java.util.zip.DataFormatException;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

public class CompressionTools {

  // Export only static methods
  private CompressionTools() {}

  public static byte[] compress(byte[] value, int offset, int length, int compressionLevel) {  
    ByteArrayOutputStream bos = new ByteArrayOutputStream(length);

    Deflater compressor = new Deflater();

    try {
      compressor.setLevel(compressionLevel);  //将当前压缩级别设置为指定值。
      compressor.setInput(value, offset, length);
      compressor.finish(); //调用时，指示压缩应当以输入缓冲区的当前内容结尾。

      // Compress the data
      final byte[] buf = new byte[1024];
      while (!compressor.finished()) { 
    //如果已到达压缩数据输出流的结尾，则返回 true。
        int count = compressor.deflate(buf);
         // 使用压缩数据填充指定缓冲区。
        bos.write(buf, 0, count);
      }
    } finally {
      compressor.end(); //关闭解压缩器并放弃所有未处理的输入。
    }

    return bos.toByteArray();
  }
  
  public static byte[] compress(byte[] value, int offset, int length) {
    return compress(value, offset, length, Deflater.BEST_COMPRESSION);
  // 最佳压缩的压缩级别
  }
  
   public static byte[] compress(byte[] value) {
    return compress(value, 0, value.length, Deflater.BEST_COMPRESSION);
  }

   public static byte[] decompress(byte[] value) throws DataFormatException {
    ByteArrayOutputStream bos = new ByteArrayOutputStream(value.length);

    Inflater decompressor = new Inflater();

    try {
      decompressor.setInput(value);
   
      final byte[] buf = new byte[1024];
      while (!decompressor.finished()) {
        int count = decompressor.inflate(buf);
        bos.write(buf, 0, count);
      }
    } finally {  
      decompressor.end();
    }
    
    return bos.toByteArray();
  }
   
   public static byte[] decompressXML(byte[] data) throws DataFormatException
   {
    byte[] dest = new byte[data.length+2];
    System.arraycopy(data, 0, dest, 2, data.length);
    dest[0] = 0x78;
    dest[1] = 0x01;
    data = dest;
    Inflater decompresser = new Inflater();
    decompresser.setInput(data);
    
    byte[] bufferArray = new byte[1024];
    ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
    try
    {
     int i = 1;
     while (i != 0)
     {
      i = decompresser.inflate(bufferArray);
      baos.write(bufferArray, 0, i);
     }
     data = baos.toByteArray();
    }
    catch (Exception e)
    {
     e.printStackTrace();
    }
    finally
    {
     try
     {
      baos.flush();
      baos.close();
     }
     catch (IOException e)
     {
      e.printStackTrace();
     }
    }
    
    decompresser.end();
    return data;
   }

}