本文系本人原創，首先發布在我的個人博客上，SpringBoot + websocket 實現模擬設備上下線，轉載請注明出處。
之前有做過車聯網項目，gps設備都會有上下線檢測的功能，但有的時候沒有真實設備測試，如何模擬設備上下線呢？可以使用websocket實現，因為它是長連接，性能開銷小且通信高效。
下面就直接上代碼
pom.xml
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<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-websocket</artifactId>
<version>1.3.5.RELEASE</version>
</dependency>
</dependencies>
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DemoApplication.java
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@SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
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WebSocketServer.java
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package com.example.demo.websocket;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
@ServerEndpoint(value = "/{deviceId}")
@Component
public class WebSocketServer {
private static final Logger logger = LoggerFactory.getLogger(WebSocketServer.class);
/**
* 存放每個客戶端對應的MyWebSocket對象
*/
private static ConcurrentHashMap<String,WebSocketServer> webSocketMap = new ConcurrentHashMap<>();
/**
* 與某個客戶端的連接會話，需要通過它來給客戶端發送數據
*/
private Session session;
/**
* 連接建立成功調用的方法
* */
@OnOpen
public void onOpen(Session session,@PathParam(value = "deviceId") String deviceId) {
this.session = session;
//判斷當前設備是否已有web socket連接，有則刪除
deleteWebsocketExisted(deviceId);
//保存當前websocket連接
webSocketMap.put(deviceId, this);
// 通知客戶端建立連接成功
sendMessage(deviceId + "connected success");
//設備狀態變化(設備連接成功通知)
statusChange(deviceId, true);
}
/**
* 收到客戶端消息后調用的方法
* @param message 客戶端發送過來的消息
* */
@OnMessage
public void onMessage(String message) {
if("ping".equals(message)){
// 心跳
sendMessage(message);
}else{
// 省略業務消息處理步驟
// 返回消息給客戶端
sendMessage("some message");
}
}
/**
* 連接關閉調用的方法
* */
@OnClose
public void onClose() {
String deviceId = getKey(webSocketMap, this);
// 從set中刪除
webSocketMap.remove(deviceId);
//設備下線
statusChange(deviceId, false);
}
/**
* 發生錯誤時調用
* */
@OnError
public void onError(Throwable error) {
logger.error("Error:"+error.getMessage());
}
private void statusChange(String deviceId, boolean status) {
if (status) {
logger.info("設備{}上線", deviceId);
}else{
logger.info("設備{}下線", deviceId);
}
// 省略操作數據庫步驟
}
private void deleteWebsocketExisted(String deviceId) {
WebSocketServer oldConnection = webSocketMap.get(deviceId);
if(null != oldConnection){
try {
oldConnection.getSession().close();
} catch (IOException e) {
logger.error("IOException:{}"+e.getMessage());
}
}
}
/**
* 根據map的value獲取map的key
* @param map
* @param myWebSocket
* @return
*/
private static String getKey(Map<String,WebSocketServer> map,WebSocketServer myWebSocket){
String key="";
for (Entry<String, WebSocketServer> entry : map.entrySet()) {
if(myWebSocket.equals(entry.getValue())){
key=entry.getKey();
}
}
return key;
}
public void sendMessage(String message) {
this.session.getAsyncRemote().sendText(message);
}
public Session getSession() {
return session;
}
}
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WebSocketConfig.java
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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();
}
}
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application.properties
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server.port=5656
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啟動springboot,這時就可以在客戶端模擬調用了,就是這個地址
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ws://localhost:5656/123456789
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123456789是設備id
問題總結
1.WebSocketServer里是無法通過@autowired或者@resource注入bean的
2.如果是打包成war到外部tomcat運行，則不需要WebSocketConfig.java這個配置類