jsp下载的几种方式：1、运用struts的下载类DownloadAction 2、直接流化

1、第一种使用struts下载比较简单。需要继承DownloadAction。然后重写getStreamInfo方法。把InputStream流放入内部类中就行了。

package cn.finefuture.common.faxserver.struts;import java.io.IOException;import java.io.InputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts.action.ActionForm;import org.apache.struts.action.ActionForward;import org.apache.struts.action.ActionMapping;import org.apache.struts.actions.DownloadAction;import cn.finefuture.common.faxserver.service.FaxServerService;import cn.finefuture.common.faxserver.service.impl.FaxServerServiceImp;public class FaxDownAction extends DownloadAction {private FaxServerService faxServerService = new FaxServerServiceImp();public void setFaxServerService(FaxServerService faxServerService) {this.faxServerService = faxServerService;}@Overrideprotected StreamInfo getStreamInfo(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {// 传真编号String faxId = request.getParameter("faxId");InputStream inStream = null;if (faxId != null && !(faxId.equals(""))) {//获取InputStreaminStream = this.faxServerService.getFaxInAtt(faxId);}final InputStream in = inStream;final String contentType = "application/file";// 建<mce:script type="text/javascript" src="http://hi.images.csdn.net/js/blog/tiny_mce/themes/advanced/langs/zh.js" mce_src="http://hi.images.csdn.net/js/blog/tiny_mce/themes/advanced/langs/zh.js"></mce:script><mce:script type="text/javascript" src="http://hi.images.csdn.net/js/blog/tiny_mce/plugins/syntaxhl/langs/zh.js" mce_src="http://hi.images.csdn.net/js/blog/tiny_mce/plugins/syntaxhl/langs/zh.js"></mce:script>议设置content-disposition响应信息头，否则Web浏览器在下载文件时// 无法在保存文件对话框中显示正确的文件名response.setHeader("content-disposition", "attachment; filename="+ faxId);return new DownloadAction.StreamInfo() // 使用隐式的方法实现了StreamInfo接口{public String getContentType() {return contentType;}public InputStream getInputStream() throws IOException {return in;}};}// 如果Struts动作不加file请求参数，则通过execute方法将指定目录中文件列表输出到客户端public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {// 当file参数存在时，则调用DownloadAction中的execute方法// 实际上，在DownloadAction类中的execute方法调用了getStreamInfo方法// 这条语句就相当于调用了getStreamInfo方法return super.execute(mapping, form, request, response);}}

2、第二种自己写输出流

/** * 下载附件 * * @param mapping * @param form * @param request * @param response * @return */public ActionForward doDownLoadAttachment(ActionMapping mapping,ActionForm form, HttpServletRequest request,HttpServletResponse response) {// 传真编号String faxId = request.getParameter("faxId");InputStream inStream = null;if (faxId != null && !(faxId.equals(""))) {inStream = this.faxServerService.getFaxInAtt(faxId);}// 流不等于nullif (inStream != null) {try {// 设置输出的格式response.reset();response.setContentType("bin");// 给中文字符转码faxId = new String(faxId.getBytes("GBK"), "iso8859-1");// 设置文件名response.setHeader("Content-Disposition","attachment;filename=" + faxId);// 循环取出流中的数据byte[] b = new byte[1024];int len;while ((len = inStream.read(b)) > 0) {response.getOutputStream().write(b, 0, len);}} catch (IOException e) {e.printStackTrace();} finally {try {inStream.close();} catch (IOException e) {e.printStackTrace();}}}return null;}