Servlet/Jsp实现发送压缩Web页面 Gzip技术
(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. } }
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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