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jsp中文件下载的实现
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方式一：采用RequestDispatcher進行
[java]?view plaincopy
package?cn.jbit.download.servlet;?? ?? import?java.io.IOException;?? ?? import?javax.servlet.RequestDispatcher;?? import?javax.servlet.ServletException;?? import?javax.servlet.http.HttpServlet;?? import?javax.servlet.http.HttpServletRequest;?? import?javax.servlet.http.HttpServletResponse;?? ?? public?class?DownloadServlet?extends?HttpServlet?{?? ?? ????private?static?final?long?serialVersionUID?=?6765085208899952414L;?? ?? ????public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)?? ????????????throws?ServletException,?IOException?{?? ????????doPost(request,?response);?? ????}?? ?? ????public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)?? ????????????throws?ServletException,?IOException?{?? ????????String?filedownload?=?"/upload/helloworld.jar";?? ????????String?filedisplay?=?"helloworld.jar";?? ????????response.setContentType("application/x-download");?? ?????????? ?????????? ????????response.addHeader("Content-Disposition",?"attachment;filename="?? ????????????????+?filedisplay);?? ?????????? ????????try?{?? ????????????RequestDispatcher?rd?=?request.getRequestDispatcher(filedownload);?? ????????????if(rd?!=?null)?? ????????????{?? ????????????????rd.forward(request,response);?? ????????????}?? ????????????response.flushBuffer();?? ????????}?catch?(Exception?e)?{?? ????????????e.printStackTrace();?? ????????}?? ????}?? }??
方式二：采用文件流輸出的方式下載
[java]?view plaincopy
package?cn.jbit.download.servlet;?? ?? import?java.io.BufferedInputStream;?? import?java.io.BufferedOutputStream;?? import?java.io.File;?? import?java.io.FileInputStream;?? import?java.io.IOException;?? import?java.io.InputStream;?? import?java.io.OutputStream;?? ?? import?javax.servlet.ServletException;?? import?javax.servlet.http.HttpServlet;?? import?javax.servlet.http.HttpServletRequest;?? import?javax.servlet.http.HttpServletResponse;?? ?? public?class?DownloadOfIOServlet?extends?HttpServlet?{?? ?? ????private?static?final?long?serialVersionUID?=?6765085208899952414L;?? ?? ????public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)?? ????????????throws?ServletException,?IOException?{?? ????????doPost(request,?response);?? ????}?? ?????? ????public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)?? ????????????throws?ServletException,?IOException?{?? ????????String?basePath?=?request.getSession().getServletContext().getRealPath("/upload");?? ?????????? ????????String?filedisplay?=?"helloworld.jar";?? ????????String?filedownload?=?basePath?+?File.separator?+?"helloworld.jar";?? ????????System.out.println("----------------------"+filedownload);?? ????????response.setContentType("applicaiton/x-download");?? ????????response.addHeader("Content-Disposition",?"attachment;filename="+filedisplay);?? ?????????? ????????InputStream?is?=?null;?? ????????OutputStream?os?=?null;?? ????????BufferedInputStream?bis?=?null;?? ????????BufferedOutputStream?bos?=?null;?? ?????????? ????????is?=?new?FileInputStream(new?File(filedownload));?? ????????bis?=?new?BufferedInputStream(is);?? ????????os?=?response.getOutputStream();?? ????????bos?=?new?BufferedOutputStream(os);?? ?????????? ????????byte[]?b?=?new?byte[1024];?? ????????int?len?=?0;?? ????????while((len?=?bis.read(b))?!=?-1){?? ????????????bos.write(b,0,len);?? ????????}?? ?????????? ????????bis.close();?? ????????is.close();?? ????????bos.close();?? ????????os.close();?? ????}?? }??
方式三：網頁上做超級鏈接(不推薦使用，樣服務器上的目錄資源會直接暴露給最終用戶)
[html]?view plaincopy
<a?href="/DownloadFile/upload/helloworld.jar">helloworld.jar</a>??
jsp頁面代碼：
[html]?view plaincopy
<%@?page?language="java"?import="java.util.*"?pageEncoding="UTF-8"%>?? <%?? String?path?=?request.getContextPath();?? String?basePath?=?request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";?? %>?? ?? <!DOCTYPE?HTML?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN">?? <html>?? ??<head>?? ????<base?href="<%=basePath%>">?? ????<title>My?JSP?'download.jsp'?starting?page</title>?? ????<meta?http-equiv="pragma"?content="no-cache">?? ????<meta?http-equiv="cache-control"?content="no-cache">?? ????<meta?http-equiv="expires"?content="0">?????? ??</head>?? ???? ??<body>?? ????下載1<a?href="/DownloadFile/upload/helloworld.jar">helloworld.jar</a><br/>?? ????下載2<a?href="/DownloadFile/servlet/downloadServlet">helloworld.jar</a><br/>?? ????下載3<a?href="/DownloadFile/servlet/downloadOfIOServlet">helloworld.jar</a><br/>?? ????下載4<a?href="/DownloadFile/download/filedownload.action">helloworld.jar</a><br/>?? ??</body>?? </html>??
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