spring boot 2/spring 5自带了websocket，下面是最基本的示例（包括java服务端、java客户端以及js客户端）
一、pom依赖
这里直接用了目前spring-boot的最新版本2.0.5 RELEASE.
二、websocket配置类
先定义一些常量，方便后面使用
public class GlobalConsts {
public static final String TOPIC = "/topic/greetings";
public static final String ENDPOINT = "/gs-guide-websocket";
public static final String APP_PREFIX = "/app";
public static final String HELLO_MAPPING = "/hello";
}
然后才是配置：
import com.cnblogs.yjmyzz.websocket.demo.consts.GlobalConsts;
import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;
/**
* @author junmingyang
*/
@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {
@Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker("/topic");
config.setApplicationDestinationPrefixes(GlobalConsts.APP_PREFIX);
}
@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint(GlobalConsts.ENDPOINT).withSockJS();
}
}
这个配置的主要作用是对外暴露访问的端点，以及定义客户端访问时，收发消息的方法url前缀。
三、定义收发消息的实体类
客户端发过来的消息：
import lombok.AllArgsConstructor;
import lombok.Data;
/**
* @author junmingyang
*/
@Data
@AllArgsConstructor
public class ClientMessage {
private String name;
public ClientMessage() {
}
}
服务端返回的消息：
import lombok.AllArgsConstructor;
import lombok.Data;
/**
* @author junmingyang
*/
@Data
@AllArgsConstructor
public class ServerMessage {
private String content;
public ServerMessage() {
}
@Override
public String toString() {
return content;
}
}
重要注意事项：收发的消息类，必须存在"无参的默认构造函数"，否则topic订阅会出问题，而且代码不报错！
四、定义Controller类
@Controller
public class GreetingController {
@MessageMapping(GlobalConsts.HELLO_MAPPING)
@SendTo(GlobalConsts.TOPIC)
public ServerMessage greeting(ClientMessage message) throws Exception {
// 模拟延时，以便测试客户端是否在异步工作
Thread.sleep(1000);
return new ServerMessage("Hello, " + HtmlUtils.htmlEscape(message.getName()) + "!");
}
}
这跟常规的spring mvc中的Controller一样，定义收发消息的具体url映射以及处理逻辑。
五、服务端入口
@SpringBootApplication
public class DemoWebSocketServer {
public static void main(String[] args) {
SpringApplication.run(DemoWebSocketServer.class, args);
}
}
这个类没啥好说的，唯一注意的是，实际调试中发现，这个类的package位置，最好放在"最外"层，移到子package后，client客户端会连接不上。（应该是要同步修改其它地方）
六、js客户端
html文件（主要是提供一个简单的UI）
enabled. Please enable
Javascript and reload this page!
| Greetings |
|---|
/webjars/xxx.js 这些都是webjars包里打包内置的，真正处理逻辑应用逻辑的，是对应的JS文件app.js
var stompClient = null;
function setConnected(connected) {
$("#connect").prop("disabled", connected);
$("#disconnect").prop("disabled", !connected);
if (connected) {
$("#conversation").show();
}
else {
$("#conversation").hide();
}
$("#greetings").html("");
}
function connect() {
var socket = new SockJS('/gs-guide-websocket');
stompClient = Stomp.over(socket);
stompClient.connect({}, function (frame) {
setConnected(true);
console.log('Connected: ' + frame);
stompClient.subscribe('/topic/greetings', function (greeting) {
showGreeting(JSON.parse(greeting.body).content);
});
});
}
function disconnect() {
if (stompClient !== null) {
stompClient.disconnect();
}
setConnected(false);
console.log("Disconnected");
}
function sendName() {
stompClient.send("/app/hello", {}, JSON.stringify({'name': $("#name").val()}));
}
function showGreeting(message) {
$("#greetings").append("
}
$(function () {
$("form").on('submit', function (e) {
e.preventDefault();
});
$( "#connect" ).click(function() { connect(); });
$( "#disconnect" ).click(function() { disconnect(); });
$( "#send" ).click(function() { sendName(); });
});
七、java客户端
通常有js客户端，普通Web场景就足够了，但如果需要java的客户端，可以参考下面这样：
/**
* @author junmingyang
*/
public class DemoWebSocketClient {
public static final String SEND_URL = GlobalConsts.APP_PREFIX + GlobalConsts.HELLO_MAPPING;
static public class MyStompSessionHandler extends StompSessionHandlerAdapter {
private String name;
public MyStompSessionHandler(String name) {
this.name = name;
}
private void showHeaders(StompHeaders headers) {
for (Map.Entry
System.err.print(" " + e.getKey() + ": ");
boolean first = true;
for (String v : e.getValue()) {
if (!first) {
System.err.print(", ");
}
System.err.print(v);
first = false;
}
System.err.println();
}
}
private void sendJsonMessage(StompSession session) {
ClientMessage msg = new ClientMessage(name);
session.send(SEND_URL, msg);
}
private void subscribeTopic(String topic, StompSession session) {
session.subscribe(topic, new StompFrameHandler() {
@Override
public Type getPayloadType(StompHeaders headers) {
return ServerMessage.class;
}
@Override
public void handleFrame(StompHeaders headers, Object payload) {
System.err.println(payload.toString());
}
});
}
@Override
public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
System.err.println("Connected! Headers:");
showHeaders(connectedHeaders);
subscribeTopic(GlobalConsts.TOPIC, session);
sendJsonMessage(session);
System.err.println("please input your new name:");
}
}
public static void main(String[] args) throws Exception {
WebSocketClient simpleWebSocketClient = new StandardWebSocketClient();
List
transports.add(new WebSocketTransport(simpleWebSocketClient));
SockJsClient sockJsClient = new SockJsClient(transports);
WebSocketStompClient stompClient = new WebSocketStompClient(sockJsClient);
stompClient.setMessageConverter(new MappingJackson2MessageConverter());
String url = "ws://localhost:8080" + GlobalConsts.ENDPOINT;
String name = "spring-" + ThreadLocalRandom.current().nextInt(1, 99);
StompSessionHandler sessionHandler = new MyStompSessionHandler(name);
StompSession session = stompClient.connect(url, sessionHandler).get();
//发送消息
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
for (; ; ) {
System.out.print(name + " >> ");
System.out.flush();
String line = in.readLine();
if (line == null) {
break;
}
if (line.length() == 0) {
continue;
}
ClientMessage msg = new ClientMessage(name + ": I have a new name [" + line + "]");
session.send(SEND_URL, msg);
}
}
}
大致逻辑，就是先connect，连上后，就subscribe topic(订阅主题，这样就能收到其它人说的话)，发送消息直接用session.send即可。
运行效果：
js客户端
java客户端：
附示例源代码下载：https://github.com/yjmyzz/spring-boot-websocket-sample
参考文章：
https://spring.io/guides/gs/messaging-stomp-websocket/
https://www.sitepoint.com/implementing-spring-websocket-server-and-client/
https://stackoverflow.com/questions/29386301/writing-a-client-to-connect-to-websocket-in-spring-boot
好文链接
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