如何在客户端持续显示控制器响应？

Question

在Spring MVC 3.2中，我创建了一个带有textarea的（JSP）网页。从客户端我启动一个在服务器上执行的控制台应用程序。我想在浏览器的textarea中显示此控制台应用程序的输出。

我得到一个响应，显示控制台的cmd输出。但问题是程序完成后会立即显示控制台输出。我想看到每个输出行立即更新textarea。

控制器代码

@RequestMapping(value = "/url", method = RequestMethod.POST)
public void Console(HttpServletResponse response) throws Exception {

    Process p = Runtime.getRuntime().exec("cmd /C cd \"C:\\appl\"" + "&" + "consoleApp.bat");

    BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));  

    String line = null; 
    while ((line = in.readLine()) != null) {
          response.getWriter().println(line);
          response.getWriter().flush();
          logger.info(line);
      }

 }

客户代码

$(function(){
    $('#someTag').click(function(){
        $.post("url","data",
                function(response){  
                    $('#console').append(response);     
                    var psconsole = $('#console');
                    psconsole.scrollTop(
                        psconsole[0].scrollHeight - (psconsole.height() - 10)
                    );
             });            

    });
});

的更新

我实施了一个轮询机制（见下面的代码）。然而，这是我想到的更间接的方法。如果有人得到更清晰的实现或简单的服务器推送示例，我希望看到它。

控制器代码

@RequestMapping(value = "/deploy", method = RequestMethod.POST)
public @ResponseBody String console(@RequestParam(value="request", required=false) String request) throws Exception {

    logger.info("status " + request);       

    if(request.equals("start")){
        Process p = Runtime.getRuntime().exec("cmd /C dir C:\\");

        in = new BufferedReader(new InputStreamReader(p.getInputStream()));

        return "started";
    }      

    while ((line = in.readLine()) != null) {
        logger.info(line);
        return line;
      }        

    logger.info("status finished");     
    return "finished";
 }  

客户代码

        var status = "start";
        var console = $('#console');                        

        console.append("starting" + '\r');              

        (function poll(){                   
           setTimeout(function(){
              $.ajax({ 
                  url: "deploy",
                  data: {request:  status},
                  type: "post",
                  success: function(data){     

                        if(data.indexOf("finished") !== -1){
                            console.append(data + '\r');                                
                            setTimeout(function()
                                    {console.scrollTop(console[0].scrollHeight - console.height());}
                                    , 20);                              
                            status = "finished";
                        }else if(data === ""){
                            console.append('\r');                               
                            setTimeout(function()
                                    {console.scrollTop(console[0].scrollHeight - console.height());}
                                    , 20);
                            status = "processing";                              
                            poll();                             
                        }else{
                            console.append(data + '\r');                                
                            setTimeout(function()
                                    {console.scrollTop(console[0].scrollHeight - console.height());}
                                    , 20);                              
                            status = "processing";
                            poll();
                        }                       
              }, dataType: "text"});
          }, 100);

        })();