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Servlet/Jsp实现发送压缩Web页面 Gzip技术

news 来源：原创 2024/5/7 15:55:43

（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！