Servlet/Jsp实现发送压缩Web页面 Gzip技术

来源：互联网发布：windows更新数据库编辑：程序博客网时间：2024/05/22 06:16

（1）什么话都不说，意思很简单就是实现页面的压缩后发送！据说对于篇幅比较长的页面可以提高几百倍哦！

（2）注意事项：并不是所有的游览器都支持压缩页面的发送与接收，所以要用代码来检验，如果可以则发送不可以

则按照正常的发送；

（即是：在HTTP包头中检查 Accept-Encoding报头，检查他手否包含有关gzip的项，如果支持，它使用PrintWriter封

装GZIPOutputStream，不支持的话则正常发送页面，同时加上了一个功能禁止页面压缩！）

（3）显示页面的servlet

package com.lc.ch04Gzip;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;public class LongServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out;if (GzipUtilities.isGzipSupported(request)&& !GzipUtilities.isGzipDisabled(request)) {out = GzipUtilities.getGzipWriter(response);response.setHeader("Content-Encoding", "gzip");} else {out = response.getWriter();}String docType = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 "+ "Transitional//EN\">\n";String title = "Long Page";out.println(docType + "<HTML>\n" + "<HEAD><TITLE>" + title+ "</TITLE></HEAD>\n" + "<BODY BGCOLOR=\"#FDF5E6\">\n"+ "<H1 ALIGN=\"CENTER\">" + title + "</H1>\n");String line = "Bfsdfdsfdsflah, blfsdfdsfah, blasfdsdfh, blsdfdsfah, bldfsdfsdfah. "+ "Yaddsfdsdfa, ysfdsdfadda, yadsdfsdfdsda, yasdfsdfdsfdda.";for (int i = 0; i < 10000; i++) {out.println(line);}out.println("</BODY></HTML>");out.close(); // Needed for gzip; optional otherwise.}}

（4）处理压缩的类

package com.lc.ch04Gzip;import java.io.IOException;import java.io.PrintWriter;import java.util.zip.GZIPOutputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class GzipUtilities {      public static boolean isGzipSupported      (HttpServletRequest request) {    String encodings = request.getHeader("Accept-Encoding");    return((encodings != null) &&           (encodings.indexOf("gzip") != -1));  }    public static boolean isGzipDisabled      (HttpServletRequest request) {    String flag = request.getParameter("disableGzip");    return((flag != null) && (!flag.equalsIgnoreCase("false")));  }    public static PrintWriter getGzipWriter      (HttpServletResponse response) throws IOException {    return(new PrintWriter            (new GZIPOutputStream              (response.getOutputStream())));  }}

（5）演示效果：（效果很好不过没有对比不过应该可以一般的图片不需要压缩了！）

ok！

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