Java和flash通信中数据的zlib压缩与解压缩

[来源：weni.cn | 作者：weni | 时间：2008-04-18 | 点击： <script src="http://www.5uflash.com/plus/count.php?aid=2938&amp;mid=&amp;view=yes"></script> 905 | 收藏本文   【大 中 小 】]

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上篇文章介绍和如何在java中将数据封装成flash可以直接读取的amf格式，amf虽然已经“压缩”过了（相对其他xml、json等，由于基于二进制而且比较少冗余数据，体积会小很多）。
但是还可以进一步压缩的，由于as3的bytearray支持compress和uncompress。所以我们可以在Java端将数据压缩，然后在flash端读取再解压缩，这样数据在传输过程中又会小很多。
下面就介绍使用方法，基于前篇文章的范例：

服务端：
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.Inflater;
import java.util.zip.ZipFile;
import java.util.zip.ZipInputStream;

import flex.messaging.io.SerializationContext;
import flex.messaging.io.amf.Amf3Output;
import flex.messaging.log.Log;
import flex.messaging.messages.Message;


public class Test {

/**
* @param args
*/
public static void main(String[] args)
{
SerializationContext serializationContext=new SerializationContext();
Amf3Output amfOut = new Amf3Output(serializationContext);
    ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    DataOutputStream dataOutStream = new DataOutputStream(outStream);
    amfOut.setOutputStream(dataOutStream);
    
    HashMap<String, Object> map=new HashMap<String, Object>();
    Double[] arr=new Double[10000];
    for(int index=0;index<10000;index++)
    {
     arr[index]=Math.random();
    }
    map.put("arr", arr);
    map.put("name", "weni");
    map.put("age", "27");
    try
    {
amfOut.writeObject(map);
dataOutStream.flush();
} catch (IOException e)
{
e.printStackTrace();
}

    byte[] messageBytes = outStream.toByteArray();
    
   
    
    try 
    { 
      FileOutputStream  os; 
      OutputStreamWriter  ow; 
      BufferedWriter  out; 
      os  =  new  FileOutputStream("D://test.txt"); 
      ow  =  new  OutputStreamWriter(os); 
      out  =  new  BufferedWriter(ow); 
      os.write(messageBytes);
      os.flush();
      os.close();
      messageBytes=compressBytes(messageBytes); //将数据进行压缩
      System.out.println("OK");
}catch(Exception  e) 
{
System.out.println("error  :"  +  e);                      
}
}

private static int cachesize = 1024;
private static Inflater decompresser = new Inflater();
private static Deflater compresser = new Deflater();
public static byte[] compressBytes(byte input[])
{
compresser.reset();
compresser.setInput(input);
compresser.finish();
byte output[] = new byte[0];
ByteArrayOutputStream o = new ByteArrayOutputStream(input.length);
try
{
byte[] buf = new byte[cachesize];
int got;
while (!compresser.finished())
{
got = compresser.deflate(buf);
o.write(buf, 0, got);
}
output = o.toByteArray();
} finally
{
try
{
o.close();
} catch (IOException e)
{
e.printStackTrace();
}
}
return output;
}
public static byte[] decompressBytes(byte input[])
{
byte output[] = new byte[0];
decompresser.reset();
decompresser.setInput(input);
ByteArrayOutputStream o = new ByteArrayOutputStream(input.length);
try
{
byte[] buf = new byte[cachesize];

 

 

int got;
while (!decompresser.finished())
{
got = decompresser.inflate(buf);
o.write(buf, 0, got);
}
output = o.toByteArray();
}catch(Exception e)
{
e.printStackTrace();
}finally
{
try
{
o.close();
} catch (IOException e)
{
e.printStackTrace();
}
}
return output;
}
}

客户端：
public class AMF3Test extends Sprite
{
private var loader:URLLoader;
public function AMF3Test()
{
loader=new URLLoader();
loader.load(new URLRequest("D://test5.txt"));
loader.addEventListener(Event.COMPLETE,onComplete);
loader.dataFormat=URLLoaderDataFormat.BINARY;
}

private function onComplete(evt:Event):void
{
var start:Number=getTimer();
var byte:ByteArray=loader.data as ByteArray;
byte.uncompress() //将数据进行解压缩
var obj:Object=byte.readObject();
var end:Number=getTimer();
trace("耗时："+(end-start)+"毫秒")
trace(obj.name,obj.age,obj.arr.length)
}
}