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springboot实现SSE(Server Sent Event)的示例代码

作者：爱码少年 00fly.online

SSE 全称Server Sent Event,直译一下就是服务器发送事件,本文主要为大家详细介绍了springboot实现SSE的相关知识,需要的可以参考一下

一、概述

1.SSE是何方神圣

SSE 全称Server Sent Event，直译一下就是服务器发送事件。

其最大的特点，可以简单概括为两个

2.sse与websocket区别

sse 是单通道，只能服务端向客户端发消息；而 websocket 是双通道

那么为什么有了 websocket 还要搞出一个 sse 呢？既然存在，必然有着它的优越之处

ssewebsocket
http 协议独立的 websocket 协议
轻量，使用简单相对复杂
默认支持断线重连需要自己实现断线重连
文本传输二进制传输
支持自定义发送的消息类型-

二、实现过程

下面我们以springboot工程为例，实现服务器端不间断向客户端推送数据

1.效果展示

http://124.71.129.204:8080/index

2. 简要流程

3. 源码放送

SSE工具类

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Consumer;

import org.apache.commons.lang3.RandomStringUtils;
import org.springframework.http.MediaType;
import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;

import lombok.extern.slf4j.Slf4j;

/**
 * Server-Sent Events <BR>
 * https://blog.csdn.net/hhl18730252820/article/details/126244274
 */
@Slf4j
public class SSEServer
{
    /**
     * 当前连接数
     */
    private static AtomicInteger count = new AtomicInteger(0);
    
    private static Map<String, SseEmitter> sseEmitterMap = new ConcurrentHashMap<>();
    
    public static SseEmitter connect()
    {
        String userId = RandomStringUtils.randomAlphanumeric(10);
        SseEmitter sseEmitter = new SseEmitter(0L); // 设置超时时间，0表示不过期，默认是30秒，超过时间未完成会抛出异常
        
        // 注册回调
        sseEmitter.onCompletion(completionCallBack(userId));
        sseEmitter.onError(errorCallBack(userId));
        sseEmitter.onTimeout(timeOutCallBack(userId));
        sseEmitterMap.put(userId, sseEmitter);
        log.info("create new sse connect ,current user:{}, count: {}", userId, count.incrementAndGet());
        return sseEmitter;
    }
    
    public static void batchSendMessage(String message)
    {
        sseEmitterMap.forEach((k, v) -> {
            try
            {
                v.send(message, MediaType.APPLICATION_JSON);
            }
            catch (IOException e)
            {
                log.error("user id:{}, send message error:{}", k, e.getMessage());
                removeUser(k);
            }
        });
    }
    
    public static void removeUser(String userId)
    {
        sseEmitterMap.remove(userId);
        log.info("remove user id:{}, count: {}", userId, count.decrementAndGet());
    }
    
    public static int getUserCount()
    {
        return count.intValue();
    }
    
    private static Runnable completionCallBack(String userId)
    {
        return () -> {
            log.info("结束连接,{}", userId);
            removeUser(userId);
        };
    }
    
    private static Runnable timeOutCallBack(String userId)
    {
        return () -> {
            log.info("连接超时,{}", userId);
            removeUser(userId);
        };
    }
    
    private static Consumer<Throwable> errorCallBack(String userId)
    {
        return throwable -> {
            log.error("连接异常，{}", userId);
            removeUser(userId);
        };
    }
}

sse接口

import java.util.concurrent.TimeUnit;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;

import com.fly.hello.service.SSEServer;

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import lombok.extern.slf4j.Slf4j;

@Slf4j
@Api(tags = "sse接口")
@RestController
@RequestMapping("/sse")
public class SSEController
{
    long i = -1;
    
    @ApiOperation("初始化")
    @GetMapping("/connect/{userId}")
    public SseEmitter connect(@PathVariable String userId)
    {
        SseEmitter sseEmitter = SSEServer.connect();
        if (i < 0)
        {
            new Thread(() -> sendMessage()).start();
        }
        return sseEmitter;
    }
    
    private void sendMessage()
    {
        if (i < 0) // 保证仅触发一次
        {
            log.info("Server-Sent Events start");
            while (true)
            {
                try
                {
                    TimeUnit.MILLISECONDS.sleep(1000);
                }
                catch (InterruptedException e)
                {
                }
                i = ++i % 101;
                SSEServer.batchSendMessage(String.valueOf(i));
            }
        }
    }
}

页面引用sse

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>

<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<link href="css/bootstrap.min.css" rel="external nofollow"  rel="stylesheet" type="text/css" />
<style>
body {
	margin: 10;
	font-size: 62.5%;
	line-height: 1.5;
}

.blue-button {
	background: #25A6E1;
	padding: 3px 20px;
	color: #fff;
	font-size: 10px;
	border-radius: 2px;
	-moz-border-radius: 2px;
	-webkit-border-radius: 4px;
	border: 1px solid #1A87B9
}

table {
	width: 60%;
}

th {
	background: SteelBlue;
	color: white;
}

td, th {
	border: 1px solid gray;
	font-size: 12px;
	text-align: left;
	padding: 5px 10px;
	overflow: hidden;
	white-space: nowrap;
	text-overflow: ellipsis;
	max-width: 200px;
	white-space: nowrap;
	text-overflow: ellipsis;
	text-overflow: ellipsis;
}
</style>
</head>
<title>Hello World!</title>
<script>
	let data = new EventSource("/sse/connect/001")
	data.onmessage = function(event) {
		document.getElementById("result").innerText = event.data + '%';
		document.getElementById("my-progress").value = event.data;
	}
</script>
<body>
	<div class="wrapper-page">
		<table align="center">
			<tr>
				<th colspan="4">Navigate</th>
			</tr>
			<tr>
				<td><a href="/index" rel="external nofollow"  target="_self">index</a></td>
				<td><a href="/404" rel="external nofollow"  target="_self">出错页面</a></td>
				<td><a href="/doc.html" rel="external nofollow"  target="_blank">doc.html</a></td>
				<td><a href="/h2-console" rel="external nofollow"  target="_blank">h2-console</a></td>
			</tr>
		</table>
		<div class="ex-page-content text-center">
			<h2 align="center">
				<a href="index" rel="external nofollow" >reload</a>
				<div><progress style="width: 60%" id="my-progress" value="0" max="100"></progress></div>
				<div id="result"></div>
			</h2>
			<img src="show/girl" width="600" height="600" />
			<img src="show/pic" width="600" height="600" />
		</div>
	</div>
</body>

</html>

4.完整项目

https://gitcode.com/00fly/springboot-hello

git clone https://gitcode.com/00fly/springboot-hello.git

到此这篇关于springboot实现SSE(Server Sent Event)的示例代码的文章就介绍到这了,更多相关springboot实现SSE内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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