前端使用EventSource方式向后台发送请求，后端接收到之后使用event-stream方式流式返回。可以应用在时钟、逐字聊天等场景。

前端js示例代码（向后台请求数据，并展示到“id=date”的div上）

<script type="text/javascript">if (typeof (EventSource) !== "undefined") {var eventSource = new EventSource("${root}/test/getDate");eventSource.onmessage = function (event) {document.getElementById("date").innerHTML = event.data;}eventSource.addEventListener('error', function (event) {console.log("错误：" + event);});eventSource.addEventListener('open', function (event) {console.log("建立连接：" + event);});} else {document.getElementById("date").innerHTML = "抱歉，您的浏览器不支持EventSource事件 ...";}
</script>

后端java示例

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;import javax.servlet.http.HttpServletResponse;
import java.util.Date;@Controller
@RequestMapping(value = "/test")
public class TestController {@ResponseBody@RequestMapping(value = "/getDate", produces = "text/event-stream;charset=UTF-8")public void getDate(HttpServletResponse response) throws Exception {System.out.println("getDate event start");response.setContentType("text/event-stream");response.setCharacterEncoding("UTF-8");response.setStatus(200);for (int i = 0; i < 10; i++) {response.getWriter().write("data:" + new Date() + "\n\n");response.getWriter().flush();Thread.sleep(1000);}response.getWriter().close();System.out.println("getDate event end");}}