Java EE WEB工程師教育訓練-JDBC+Servlet+JSP整合開發之15.Servlet響應頭資訊

–HTTP響應的格式 

–設定響應報頭 

–常見MIME類型 

–常見HTTP 1.1響應報頭 

–建構Excel電子表格 

–動态生成JPEG圖像 

–定時重新整理頁面

###################Michael分割線#######################

• HTTP響應的格式

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• 設定響應報頭 

– 設定任意響應頭 

• public void setHeader(String headerName, String headerValue) 

– 設定任意的報頭 

• public void setDateHeader(String name,long millisecs) 

– 将自1970年以來的毫秒數轉換成GMT格式日期字元串 

• public void setIntHeader(String name,int headerValue) 

– 可以省去在調用setHeader之前将int轉換成字元串的麻煩 

• addHeader, addDateHeader, addIntHeader 

– 增加新報頭，而非替換已有的報頭

– 普通響應報頭的設定 

• setContentType 

– 設定Content-Type報頭 

– servlet幾乎總會用到這個報頭 

– 參見常見MIME類型的表格 

• setContentLength 

– 設定Content-Length報頭 

– 用于持續性HTTP連接配接。 

– 參見Connection請求報頭 

• addCookie 

– 為Set-Cookie報頭增加一個值 

– 參見介紹cookie的部分 

• sendRedirect 

– 設定Location報頭(以及改變狀态代碼)

• 常見MIME類型

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_1245711409aR9U.png"></a>

• 常見HTTP 1.1響應報頭 

– Cache-Control (1.1) 和Pragma (1.0) 

• no-cache值阻止浏覽器緩存頁面。 

– Content-Disposition 

• 通過這個報頭，可以請求浏覽器詢問使用者将響應存儲到磁盤上給定名稱的檔案中 

• Content-Disposition: attachment; filename=file-name 

– Content-Encoding 

• 文檔的編碼方式 

– Content-Length 

• 響應中的位元組數 

– Content-Type 

• 傳回文檔時所采用的MIME類型。 

• 使用setContentType設定這個報頭。 

– Expires 

• 特定的一段時間，這段時間後應該将文檔認作是過期，不應該再繼續緩存 

• 使用setDateHeader設定這個報頭 

– Last-Modified 

• 文檔最後被改動的時間 

• 不要直接設定這個報頭，而應該提供getLastModified方法 

–Location 

• 浏覽器應該重新連接配接到的URL 

• 不要直接設定這個報頭，而要使用sendRedirect進行設定 

–Refresh 

• 多少秒後浏覽器應該重新載入頁面 

–Set-Cookie 

• 浏覽器應該記下來的cookie。不要直接設定這個報頭，而應該使用addCookie 

–WWW-Authenticate 

• 授權的類型和範圍需要在Authorization報頭中給出

• 建構Excel電子表格

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_1245711413gjmS.png"></a>

Servlet_ResponseHeader

package com.michael.servlet;    

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 PrintExcelServlet extends HttpServlet {    

        /**    

         * Constructor of the object.    

         */    

        public PrintExcelServlet() {    

                super();    

        }    

         * Destruction of the servlet. &lt;br&gt;    

        public void destroy() {    

                super.destroy(); // Just puts "destroy" string in log    

                // Put your code here    

         * The doGet method of the servlet. &lt;br&gt;    

         *    

         * This method is called when a form has its tag value method equals to get.    

         * @param request the request send by the client to the server    

         * @param response the response send by the server to the client    

         * @throws ServletException if an error occurred    

         * @throws IOException if an error occurred    

        public void doGet(HttpServletRequest request, HttpServletResponse response)    

                        throws ServletException, IOException {    

                doPost(request,response);    

         * The doPost method of the servlet. &lt;br&gt;    

         * This method is called when a form has its tag value method equals to post.    

        public void doPost(HttpServletRequest request, HttpServletResponse response)    

                response.setContentType("application/vnd.ms-excel");    

                PrintWriter out = response.getWriter();    

                out.println("\tQ1\tQ2\tQ3\tQ4\tTotal");    

                out.println("Apples\t78\t87\t92\t29\t=SUM(B2:E2)");    

                out.println("Oranges\t77\t86\t93\t30\t=SUM(B3:E3)");    

         * Initialization of the servlet. &lt;br&gt;    

         * @throws ServletException if an error occure    

        public void init() throws ServletException {    

} 

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_12457114190lm9.png"></a>

測試

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_1245711424w5hT.png"></a>

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_12457114293EWI.png"></a>

• 動态生成JPEG圖像

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_1245711775rltu.png"></a>

PrintPictureServlet.java

import java.io.InputStream;    

import java.io.OutputStream;    

public class PrintPictureServlet extends HttpServlet {    

        public PrintPictureServlet() {    

                response.setContentType("image/jpeg");    

                InputStream in = this.getClass().getClassLoader().getResourceAsStream("Michael.JPG");    

                int len = in.available();    

                byte[] buffer = new byte[len];    

                in.read(buffer);    

                //輸出流    

                OutputStream out = response.getOutputStream();    

                out.write(buffer);    

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_1245711781hVoD.png"></a>

看下效果

• 定時重新整理頁面

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_12457117913lBD.png"></a>

TimeServlet.java

import java.util.Date;    

public class TimeServlet extends HttpServlet {    

        public TimeServlet() {    

                response.setHeader("refresh", "1");    

                response.setContentType("text/html;charset=gbk");    

                out    

                                .println("&lt;!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\"&gt;");    

                out.println("&lt;HTML&gt;");    

                out.println("    &lt;HEAD&gt;&lt;TITLE&gt;A Servlet&lt;/TITLE&gt;&lt;/HEAD&gt;");    

                out.println("    &lt;BODY&gt;");    

                out.print("        目前頁面重新整理時間為： ");    

                out.print(new Date().toLocaleString());    

                out.println("    &lt;/BODY&gt;");    

                out.println("&lt;/HTML&gt;");    

                out.flush();    

                out.close();    

<a href="http://redking.blog.51cto.com/attachment/200906/22/27212_1245711796RdP3.png"></a>

看下效果：

<a href="http://down.51cto.com/data/2353142" target="_blank">附件：http://down.51cto.com/data/2353142</a>

本文轉自redking51CTO部落格，原文連結：http://blog.51cto.com/redking/168991，如需轉載請自行聯系原作者