Spring MVC4.1服务器端推送实现过程解析

package com.wisely.web;

import java.util.Random;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class SSEController {
  //注意produces="text/event-stream"
  @RequestMapping(value="/push",produces="text/event-stream")
  public @ResponseBody String push(){
     Random r = new Random();
     try {
         Thread.sleep(5000);
     } catch (InterruptedException e) {
         e.printStackTrace();
     }
     return "data:Testing 1,2,3" + r.nextInt() +"\n\n";
  }
}

<div id="msg_from_server"></div>
<script type="text/javascript" src="<c:url value="/js/jquery.js" />"></script>
<script type="text/javascript">
if (!!window.EventSource) {
    var source = new EventSource('push'); //为http://localhost:8080/testSpringMVC/push
    s='';
    source.addEventListener('message', function(e) {

      s+=e.data+"<br/>"
      $("#msg_from_server").html(s);

    });

    source.addEventListener('open', function(e) {
      console.log("连接打开.");
    }, false);

    source.addEventListener('error', function(e) {
      if (e.readyState == EventSource.CLOSED) {
        console.log("连接关闭");
      } else {
        console.log(e.readyState);  
      }
    }, false);
  } else {
      console.log("没有sse");
  }
</script>