前三个动态提供
一般后面的两个就是用struts预设
1024b  即2Kb

contentType="text/html";
    contentDisposition="attachment;filename=date.html";
    
    ServletContext context=ServletActionContext.getServletContext();
    String fileName=context.getRealPath("/files/date.html");
    inputStream=new FileInputStream(fileName);
    
    contentLength=inputStream.available();



<result type="stream">
    <param name="bufferSize">2048</param>
    
    </result>