用Jsp來實現文件下載功能的幾種方式

URLConnection con;
        try {
            //url是被調用的SERVLET的網址 如 *.do 
            con = url.openConnection();
            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, "正在從服務器下載文件內容", in);
            ProgressMonitor pMonitor = pmInputStream.getProgressMonitor();
            pMonitor.setMillisToDecideToPopup(3);
            pMonitor.setMillisToPopup(3);
            //localfilepath本地路徑,localstr文件文件夾，filename本地文件名
            String localfilepath = localstr + filename ;
            //方法saveFilsaveFilee是把輸入流pmInputStream寫到文件localfilepath中 
            if(saveFilsaveFilee(localfilepath,pmInputStream)){
　　　　        openLocalFile(localfilepath);
            }