android客户端使用网络数据压缩

GZIPInputStream

面试遇到了网络数据压缩的问题，本来问道这个问题前我也看过Gzip，不是很理解，龙哥提示要把网络两个字去掉就有思路了，再次提示下我才看到gzip方式。

Gzip也是android客户端支持的方式，官网解释：GZIPInputStream此类类是用来读取在GZIP格式存储的数据，从底层的流进它的缓冲区读取和解压GZIP数据。

 InputStream is = ...
 GZIPInputStream zis = new GZIPInputStream(new BufferedInputStream(is));
 try {
     // Reading from 'zis' gets you the uncompressed bytes...
     processStream(zis);
 } finally {
     zis.close();
 }

比较实际的配置说明http://www.blogjava.net/site120/archive/2007/02/16/100073.html

servlet的作法

1， 工具类：测试客户端是否支持GZIP编码压缩方式 & 获得支持GZIP的PrintWriter对象

package freebsd;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.zip.GZIPOutputStream;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class Utilities {
/*
* 测试客户端浏览器是否支持gzip的编码方式
*/
public static boolean isSurpported(HttpServletRequest request)
{
   String encodingString = request.getHeader("Accept-Encoding");
   return (encodingString!=null) && (encodingString.indexOf("gzip")!=-1);
}
/*
* 取得一个压缩的PrintWriter
*/
public static PrintWriter getWriter(HttpServletResponse response) throws IOException
{
   ServletOutputStream sos = response.getOutputStream();
   GZIPOutputStream gzipos = new GZIPOutputStream(sos);
   return new PrintWriter(gzipos);
}

}
2，Servlet类，产生一个长字符串，然后在html页面中请求该servlet:

import freebsd.*;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
* Servlet implementation class ServletGzip
*/
public class ServletGzip extends HttpServlet {
private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public ServletGzip() {
        super();
        // TODO Auto-generated constructor stub
    }

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   doPost(request, response);
}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   response.setContentType("text/html");
   response.setStatus(response.SC_OK);
   PrintWriter out;
   if(Utilities.isSurpported(request))
   {
    out = Utilities.getWriter(response);

   //协议： 通知客户端使用gzip这种压缩方式而不是其它的，如compress
   response.setHeader("Content-Encoding", "gzip")；
   }else {
    out = response.getWriter();
   }
  StringBuilder sBuilder = new StringBuilder();
   for(int i=0; i!=5000; ++i)
   {
    sBuilder.append("Printing the long string... ...!");
   }
   out.println(sBuilder);
out.close();
}
}