jsp檔案下載方法

<%
 response.setContentType(fileminitype);
 response.setHeader("Location",filename);
 response.setHeader("Cache-Control", "max-age=" + cacheTime);
 response.setHeader("Content-Disposition", "attachment; filename=" + filename); //filename應該是編碼後的(utf-8)
 response.setContentLength(filelength);
 OutputStream outputStream = response.getOutputStream();
 InputStream inputStream = new FileInputStream(filepath);
 byte[] buffer = new byte[1024];
 int i = -1;
 while ((i = inputStream.read(buffer)) != -1) {
  outputStream.write(buffer, 0, i);
  }
 outputStream.flush();
 

 outputStream.close();
 inputStream.close();
 outputStream = null;
%>
３。既然是JSP的話，還有一種方式就是用Applet來實現檔案的下載。不過客戶首先得信任你的這個Applet小程式，由這個程式來接受由servlet發送來的資料流，並寫入到本地。
servlet端樣本
    public void service(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        res.setContentType(" text/plain ");
        OutputStream outputStream = null;
        try {
            outputStream = res.getOutputStream();
            popFile(srcFile, outputStream)) ;//把檔案路徑為srcFile的檔案寫入到outputStream中。
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
JApplet端樣本
   URLConnection con;
        try {
            con = url.openConnection();//url是被調用的SERVLET的網址 如http://localhost:8080/sendDateSevlet.do 
            con.setUseCaches(false);
            con.setDoInput(true);
            con.setDoOutput(true);
            con.setRequestProperty("Content-Type",
                "application/octet-stream");
            InputStream in = con.getInputStream();
            ProgressMonitorInputStream pmInputStream = new ProgressMonitorInputStream(
                    pane, "正在從伺服器下載檔案內容", in);
            ProgressMonitor pMonitor = pmInputStream
                    .getProgressMonitor();
            pMonitor.setMillisToDecideToPopup(3);
            pMonitor.setMillisToPopup(3);
            String localfilepath = localstr + filename ;//localfilepath本地路徑,localstr檔案檔案夾，filename本地檔案名稱
   　　if(saveFilsaveFilee(localfilepath,pmInputStream)){　//方法saveFilsaveFilee是把輸入資料流pmInputStream寫到檔案localfilepath中。                   
　　　　　openLocalFile(localfilepath);
            }

４。順便把JApplet上傳檔案的代碼也貼上來.
JApplet端樣本
URLConnection con;
        try {
            con = url.openConnection();//url是被調用的SERVLET的網址 如http://localhost:8080/sendDateSevlet.do        
　　   con.setUseCaches(false);
            con.setDoInput(true);
            con.setDoOutput(true);
            con.setRequestProperty("Content-Type",
                "application/octet-stream");
           
            OutputStream out = con.getOutputStream();
            String localfilepath = localstr + filename; //localfilepath本地路徑,localstr檔案檔案夾，filename本地檔案名稱
            getOutputStream(localfilepath,out);//檔案getOutputStream是把檔案localfilepath寫到輸出資料流out中。
            InputStream in = con.getInputStream();
            return true;
        }catch (IOException e) {
               System.out.println("檔案上傳出錯！");
            e.printStackTrace();
        }
servlet端程式碼範例
    public void service(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        res.setContentType(" text/plain ");
        InputStream inputStream = null;
        try {
            inputStream = res.getInputStream();
            writefile(srcFile, inputStream);//把輸入資料流inputStream儲存到檔案路徑為srcFile的檔案中
        } catch (IOException e) {
            e.printStackTrace();
        }
    } // end service