頁面引入：jquery-form.js

function importSaleOrder(){

            var file=$("#file").val();
            if(file!=""){
                $("#errorInfo").html("");
                $("#downErrorFile").hide();
                var form = $("form[id=importSaleOrderFrom]");  
                var options  = {    
                    url:ctx+'/warehouse-out/importBatchWhoutSaleOrder.jhtml'
 
,    
                    type:'post', 
                    success:function(data)    
                    {    
                         var fileName = data.filePath;
                         var errors = data.errors;
                         $("#errorInfo").html(errors);
                         $("#downErrorFile"
 
).show();
                         $("#downErrorFile").attr("href",ctx+'/warehouse-out/downloadExcel.jhtml?fileFileName='+fileName);
                    }    
                };    
                form.ajaxSubmit(options);  
            }else{
                alert("請選擇檔案！");
            }

    }



下載：
public String downloadExcel(){
        String realPath = ServletActionContext.getServletContext().getRealPath("/"
 
)+"/upload";
        File file = new File(realPath,fileFileName);
        downloadExcel(file, response);
        return null;
    }

/**
     * 報表檔案下載
     * @param file
     * @param response
     */
    public void downloadExcel(File file, HttpServletResponse response) {  
        try {  
            // 取得檔名。  
            String filename = file.getName(); 
            String userAgent = request.getHeader("USER-AGENT");
                String finalFileName = null;
                if(StringUtils.contains(userAgent, "MSIE")){//IE瀏覽器
                    finalFileName = URLEncoder.encode(filename,"UTF8");
                }else if(StringUtils.contains(userAgent, "Mozilla")){//google,火狐瀏覽器
                    finalFileName = new String(filename.getBytes(), "ISO8859-1");
                }else{
                    finalFileName = URLEncoder.encode(filename,"UTF8");//其他瀏覽器
                }
            // 以流的形式下載檔案。  
            InputStream fis = new BufferedInputStream(new FileInputStream(file));  
            byte[] buffer = new byte[fis.available()];  
            fis.read(buffer);  
            fis.close();  
            // 清空response  
            response.reset();  
            // 設定response的Header  
            response.addHeader("Content-Disposition", "attachment;filename="  
                    + finalFileName);  
            response.addHeader("Content-Length", "" + file.length());  
            OutputStream toClient = new BufferedOutputStream(  
                    response.getOutputStream());  
            response.setContentType("application/vnd.ms-excel;charset=gb2312");  
            toClient.write(buffer);  
            toClient.flush();  
            toClient.close();  


        } catch (IOException ex) {  
            ex.printStackTrace();  
        }  
        if(file.exists()){
            file.delete();
        }
    }



<form id="importSaleOrderFrom" action="${pageContext.request.contextPath}/warehouse-out/importBatchWhoutSaleOrder.jhtml" method="post" enctype="multipart/form-data">

                        <div class="col-md-7">
                              <div class="form-group">
                                <input id="file" type="file" name="file" onchange="clearForm()" >
                              </div>
                        <input type="button" value="匯入解析"  onclick="importSaleOrder()" />

                        <label id="errorInfo" style="margin-left:20px;color: red;"></label>
                        <a href="#" style="display: none" id="downErrorFile" style="margin-left:40px;">下載檔案</a> 
                        </div>
                    </form>