servlets - 文本/事件流从头开始渲染(没有插件)

Question

要使用push方法，我们使用著名的JS对象EventSource:

这是易于开发的客户端部分:

        var eventSource = new EventSource("controller/action");

        eventSource.onmessage = function(event) {

            document.getElementById('foo').innerHTML = event.data;

        };

但是，我很难在服务器部分(Grails)中配置push方法。

当我查看由Servlets开发的JEE应用程序时，我可以看到服务器部分如下:

http://viralpatel.net/blogs/html5-server-sent-events-java-servlets-example/

public class TestServlet extends HttpServlet {


    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        //content type must be set to text/event-stream
        response.setContentType("text/event-stream");  

        //encoding must be set to UTF-8
        response.setCharacterEncoding("UTF-8");

        PrintWriter writer = response.getWriter();

        for(int i=0; i<10; i++) {

            writer.write("data: "+ System.currentTimeMillis() +"\n\n");

            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        writer.close();
    }
}

要将这个servlet转换为 Action Controller :

def push(){

        render(contentType:'text/event-stream',characterEncoding:'UTF-8'){
              [dt:"data: "+ System.currentTimeMillis() +"\n\n"]             
        }
}

在客户端部分:

 var eventSource = new EventSource(baseURL+"external/push");
 eventSource.onmessage=function(e){
     console.log(e.data.dt);
 }

不幸的是，我在console上没有任何结果。

Answer 1

我不确定render方法是否可以正确处理'text/event-stream'，但是您可以直接在操作中访问response对象:

def push() {
  //content type must be set to text/event-stream
  response.setContentType("text/event-stream");  

  //encoding must be set to UTF-8
  response.setCharacterEncoding("UTF-8");

  for(int i=0; i<10; i++) {

    response.outputStream.write("data: "+ System.currentTimeMillis() +"\n\n");
    try {
      Thread.sleep(1000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }
  response.outputStream.flush()
}