java下載檔案

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檔案下載不需要第三包就是靠檔案流、位元組輸入輸出資料流實現。

<table>      <tr>          <td align="right">          <a href="download.jsp?path=<%=getServletContext().getRealPath("123.png") %>">下載</a></td>      </tr>      </table>

download.jsp

<%        response.setCharacterEncoding("utf-8");        String pathname = request.getParameter("path");        pathname = new String(pathname.getBytes("iso-8859-1"));        File file = new File(pathname);        InputStream ins = new FileInputStream(file);        OutputStream os = response.getOutputStream();        BufferedInputStream bis = new BufferedInputStream(ins);        BufferedOutputStream bos = new BufferedOutputStream(os);        response.addHeader("Content-Disposition","attachment;filename="+new String(file.getName().getBytes("utf-8"),"iso-8859-1"));        response.addHeader("Content-Length",file.length()+"");        response.setContentType("application/octet-stream");        int len = 0;        byte[] bys = new byte[1024];        while((len=ins.read(bys))!=-1){            bos.write(bys);            bos.flush();        }        out.clear();        out = pageContext.pushBody();        bos.close();        bis.close();     %>

上述代碼中調用了out.clear()和pageContext.pushBody()方法，是因為在JSP頁面中內建有out,再使用response.getOutStream()方法會拋出java.lang.IllegalStateException異常，不過上述代碼中本人去掉這兩行也沒錯。

java下載檔案