声明：代码是JavaEE开发的颠覆者 Spring Boot实战代码中的，我买了这书，并练习

1只有火狐和谷歌支持浏览器消息推送

@Controller
public class SseController {
	
	@RequestMapping(value="/pushMessage",produces="text/event-stream") //1
	public @ResponseBody String push(){
		 Random r = new Random();
        try {
                Thread.sleep(1000);
        } catch (InterruptedException e) {
                e.printStackTrace();
        }   
        return "data: " + r.nextInt() +"\n\n";
	}
}
-------------------------
jsp文件

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>SSE Demo</title>

</head>
<body>


<div id="msgFrompPush"></div>
<script type="text/javascript" src="<c:url value="assets/js/jquery.js" />"></script>
<script type="text/javascript">
 if (!!window.EventSource) { //1
	   var source = new EventSource('pushMessage');
	   s='';
	   source.addEventListener('message', function(e) {//2
		   s+=e.data+"<br/>";
		   $("#msgFrompPush").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("你的浏览器不支持SSE");
	} 
</script>
</body>
</html>

请求跳转到指定页面，指定页面执行js方法去刷消息

2跨浏览器，servert3.0+异步方法处理

@Service
public class PushService {
    private DeferredResult<String> deferredResult; //1

    public DeferredResult<String> getAsyncUpdate() {
        deferredResult = new DeferredResult<String>();
        return deferredResult;
    }

    @Scheduled(fixedDelay = 5000)
    public void refresh() {
        if (deferredResult != null) {
            deferredResult.setResult(new Long(System.currentTimeMillis())
                    .toString());
        }
    }
}

------------------
@Controller
public class AysncController {
    @Autowired
    PushService pushService; //1

    @RequestMapping("/defer")
    @ResponseBody
    public DeferredResult<String> deferredCall() { //2
        System.out.println("11111");
        return pushService.getAsyncUpdate();
    }

}

-------------------
@Configuration
@EnableWebMvc// 1
@EnableScheduling
@ComponentScan("com.wisely.highlight_springmvc4")
public class MyMvcConfig extends WebMvcConfigurerAdapter {// 2
	@Bean
	public InternalResourceViewResolver viewResolver() {
		InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
		viewResolver.setPrefix("/WEB-INF/classes/views/");
		viewResolver.setSuffix(".jsp");
		viewResolver.setViewClass(JstlView.class);
		return viewResolver;
	}
	@Override
	public void addResourceHandlers(ResourceHandlerRegistry registry) {

		registry.addResourceHandler("/assets/**").addResourceLocations(
				"classpath:/assets/");// 3

	}
	@Override
	public void addViewControllers(ViewControllerRegistry registry) {
		registry.addViewController("/async").setViewName("/async");
	}
}
------------------

public class WebInitializer implements WebApplicationInitializer {//1
	@Override
	public void onStartup(ServletContext servletContext)
			throws ServletException {
		AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(MyMvcConfig.class);
        ctx.setServletContext(servletContext); //2
        
        Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(ctx)); //3
        servlet.addMapping("/");
        servlet.setLoadOnStartup(1);
        servlet.setAsyncSupported(true);//1

	}

}

客户端请求一次，等待服务器响应，收到响应再请求，循环

springboot消息推送

1只有火狐和谷歌支持浏览器消息推送

2跨浏览器，servert3.0+异步方法处理

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