jsf 附件上载代码

jsf 附件下载代码

前台页面大概如下：

 

 <h:commandLink value="下载" action="#{KnowledgeItemAction.download}">
         <f:param name="fileName" value="#{file.saveName}"/>
          <f:param name="testPath" value="${facesContext.externalContext.requestContextPath}"/>
  </h:commandLink>

 

后台代码如下：

 

public void download() {
       String str = FacesContext.getCurrentInstance().getExternalContext()
        .getRequestParameterMap().get( "fileName" ); 

       
       if(null != str ){
        String filePath = Util.PATH  + str;    // 得到文件路径
        try {
            FacesContext ctx = FacesContext.getCurrentInstance();
            ctx.responseComplete();  //此步必须有否则会出现：Servlet response already use stream  异常HttpServletResponse response=(HttpServletResponse)ctx.getExternalContext().getResponse();
            File f = new File(filePath);
            if (!f.exists()) {
                response.sendError(404, "File not found!");
                return;
            }
            BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));
            byte[] buf = new byte[1024];
            int len = 0;

            response.reset(); // 非常重要
            response.setContentType("application/x-msdownload;charset=gbk");
            response.setHeader("Content-Disposition", "attachment; filename="
            + f.getName());
           
            OutputStream out = response.getOutputStream();
            while ((len = br.read(buf)) > 0)
            out.write(buf, 0, len);
            br.close();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
       }
    }