WebSocket的使用

一、J2EE的websocket

1、新建Springboot项目，我这里使用的版本是2.5.7，添加websocket依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
</dependency>

2、配置类

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

@Configuration
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter(){
        return new ServerEndpointExporter();
    }
}

3、服务端ServerEndpoint

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;

@Slf4j
@Component
@ServerEndpoint("/ws/{userName}")
public class MyServerEndpoint {

    public void sendMessage(Session session, String message) throws IOException {
        log.info("准备向客户端程序{}发送消息:{}", session.getId(), message);
        session.getBasicRemote().sendText(message);
    }

    @OnMessage
    public void onMessage(@PathParam("userName") String userName,String message, Session session) {
        log.info("收到来自客户端{}的消息! sessionId: {}, 消息：{}", userName, session.getId(), message);
        try {
            sendMessage(session, message);
        } catch (IOException e) {
            log.error("消息发送失败!", e);
        }
    }

    @OnOpen
    public void onOpen(@PathParam("userName") String userName, Session session) {
        log.info("客户端程序{}建立连接成功! sessionId:{}", userName, session.getId());
    }

    @OnClose
    public void onClose(@PathParam("userName") String userName, Session session, CloseReason closeReason) {
        log.info("客户端{}断开连接，原因：{}", userName, closeReason);
    }

    @OnError
    public void onError(Session session, Throwable throwable) {
        log.info("连接{}发生错误!", session.getId());
        throwable.printStackTrace();
    }
}

其他的可以不用配置，ServerEndpointExporter这个Bean中的registerEndpoints会将标注了@ServerEndpoint注解的Bean注册到ServerContainer中。

4、测试

（1）使用主流浏览器进行测试

主流浏览器都支持websocket，可以新建个HTML文件，使用下述的JavaScript代码进行测试，也可以直接使用浏览器的控制台进行测试。

const ws = new WebSocket('ws://localhost:8080/ws/zhangsan');
ws.onmessage = messageEvent => {
  console.log('onmessage: ', messageEvent.data)
}
ws.onopen = messageEvent => {
  console.log('onopen: ', messageEvent)
}
ws.onclose = messageEvent => {
  console.log('onclose: ', messageEvent)
}
ws.onerror = messageEvent => {
  console.log('onerror: ', messageEvent)
}

// 发送消息
ws.send('hello world~')

（2）使用对应的ClientEndpoint进行测试

import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;

import javax.websocket.*;
import java.io.IOException;
import java.net.URI;
import java.util.concurrent.TimeUnit;

@Slf4j
@ClientEndpoint
public class ClientEndpointTest {

    @OnOpen
    public void onOpen(Session session, EndpointConfig config) {
        log.info("连接成功！sessionID：{}，config：{}", session.getId(), config);
    }

    public ClientEndpointTest() {
        super();
    }

    @OnClose
    public void onClose(Session session, CloseReason closeReason) {
        log.warn("关闭连接！sessionId：{}，关闭原因：{}", session.getId(), closeReason);
    }

    @OnError
    public void onError(Session session, Throwable throwable) {
        log.error("出错了！sessionId：{}", session.getId(), throwable);
    }

    @OnMessage
    public void onMessage(Session session, String message) {
        log.info("收到消息！sessionId: {}，message：{}", session.getId(), message);
        doOnMsg(session, message);
    }

    protected void doOnMsg(Session session, String message) {

    }

    @Slf4j
    @ClientEndpoint
    public static class Client2 extends ClientEndpointTest {
        @Override
        protected void doOnMsg(Session session, String message) {
            log.info("client2 doOnMsg:{},{}", session.getId(), message);
        }
    }

    @Test
    void endpointTest() throws DeploymentException, IOException, InterruptedException {
        WebSocketContainer container = ContainerProvider.getWebSocketContainer();

        Session session1 = container.connectToServer(ClientEndpointTest.class, URI.create("ws://localhost:8080/ws/zhangsan"));
		// 不能使用匿名类，需要有@ClientEndpoint注解的类才行
        Session session2 = container.connectToServer(new ClientEndpointTest.Client2(), URI.create("ws://localhost:8080/ws/lisi"));

        session1.getBasicRemote().sendText("张三发送的消息！");
        session2.getBasicRemote().sendText("李四发送的消息！");
        
        TimeUnit.SECONDS.sleep(1);

        session1.close(new CloseReason(CloseReason.CloseCodes.NO_STATUS_CODE, "主动断开的。。"));
        session2.close(new CloseReason(CloseReason.CloseCodes.NO_STATUS_CODE, "主动断开的。。"));

        TimeUnit.SECONDS.sleep(2);
    }

}

（3）使用SpringWebSocket提供的客户端进行测试，相对来说，这种方式更加灵活一些，更便于扩展

@Test
void standardClientTest() throws InterruptedException {
    WebSocketClient client = new StandardWebSocketClient();
    WebSocketHttpHeaders headers = new WebSocketHttpHeaders();
    headers.set("token", "xxxx");
    CountDownLatch countDownLatch = new CountDownLatch(1);

    URI uri = UriComponentsBuilder.fromUriString("ws://localhost:8080/ws/{userName}").buildAndExpand("zhangsan123").toUri();
    client.doHandshake(new TextWebSocketHandler() {
        @Override
        protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
            log.info("收到服务端消息：{}", message.getPayload());
        }
    }, headers, uri)
        .addCallback(new ListenableFutureCallback<WebSocketSession>() {
            @Override
            public void onFailure(Throwable ex) {
                ex.printStackTrace();
            }

            @Override
            public void onSuccess(WebSocketSession session) {
                log.info("连接成功！{}", session.getId());
                try {
                    session.sendMessage(new TextMessage("来自客户端的问候~"));
                    TimeUnit.SECONDS.sleep(3);
                    countDownLatch.countDown();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    countDownLatch.await();

}

二、SpringFramework提供的websocket

1、依赖与第一种一样

2、配置类

@Slf4j
@Configuration
@EnableWebSocket
public class SockConfig implements WebSocketConfigurer {

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(echoWebSocketHandler(), "/ws/{userName}")
            .setAllowedOriginPatterns("*")
            .setHandshakeHandler(new DefaultHandshakeHandler())
            .addInterceptors(new HttpSessionHandshakeInterceptor() {
                @Override
                public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {
                    // 认证等操作。。。
                    return true;
                }
            });
    }

    public WebSocketHandler echoWebSocketHandler() {
        return new TextWebSocketHandler() {
            @Override
            protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
                // 收到的信息
                String requestMsg = message.getPayload();
                System.out.println("服务器收到：" + requestMsg);
                // 组织响应信息
                String responseMsg = "服务器返回: " + requestMsg;
                System.out.println(responseMsg);
                TextMessage respMsg = new TextMessage(responseMsg.getBytes(StandardCharsets.UTF_8));
                // 返回给客户端
                session.sendMessage(respMsg);
            }
        };
    }
}

3、测试方式与第一种一样

WebSocket中Stomp的下次再写吧。