搭建局域网WebSocket手机和Web遥控器

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这里以遥控Android平台的机顶盒或应用为例，实现基于WebSocket的遥控通信。这里以遥控机顶盒为例。WebSocket支持双向通信。WebSocket是一种在单个TCP连接上进行全双工通信的协议。允许服务端主动向客户端推送数据，浏览器/客户端和服务器只需要完成一次握手，两者之间就直接可以创建持久性的连接，并进行双向数据传输。很多推送功能就是基于WebSocket进行实现的通信推送。

WebSocket优点：

较少的控制开销；
更强的实时性；
保持连接状态；
更好的二进制支持；
可以支持扩展；
更好的压缩效果等。

更详细的WebSocket介绍和用法：

目前有两种方式实现通信遥控：

一个是基于局域网的，即服务器和客户端在一个网络下，可以在机顶盒应用里内置WebSocket服务端Server，手机和网页作为客户端发送指令。
另一个是搭建一个公网中转服务器Server，手机/网页、机顶盒都作为客户端，这样客户端都需要知道服务器端地址去主动连接。这样就不会局限于同一个网络通信，手机/网页发送的消息通过服务器端中转再传统给机顶盒客户端。当然，这样也有弊端，就是增大了通信运营成本、安全性、也可能会有延迟、服务器一旦出问题，所有客户端都无法正常工作等。

先看第一种，这里采用Java搭建WebSocket服务器，内置到机顶盒内。

这里用到了开源库：Java-WebSocket（ ）

st.ws.utils;import org.java_websocket.WebSocket;
import org.java_websocket.handshake.ClientHandshake;
import org.java_websocket.server.WebSocketServer;import java.InetSocketAddress;
import java.nio.ByteBuffer;public class SimpleServer extends WebSocketServer {public SimpleServer(InetSocketAddress address) {super(address);}@Overridepublic void onOpen(WebSocket conn, ClientHandshake handshake) {conn.send("Welcome to the server!"); //This method sends a message to the new clientbroadcast( "new connection: " + ResourceDescriptor() ); //This method sends a message to all clients connectedSystem.out.println("new connection to " + RemoteSocketAddress());}@Overridepublic void onClose(WebSocket conn, int code, String reason, boolean remote) {System.out.println("closed " + RemoteSocketAddress() + " with exit code " + code + " additional info: " + reason);}@Overridepublic void onMessage(WebSocket conn, String message) {System.out.println("received message from "	+ RemoteSocketAddress() + ": " + message);}@Overridepublic void onMessage( WebSocket conn, ByteBuffer message ) {System.out.println("received ByteBuffer from "	+ RemoteSocketAddress());}@Overridepublic void onError(WebSocket conn, Exception ex) {println("an error occured on connection " + RemoteSocketAddress()  + ":" + ex);}@Overridepublic void onStart() {System.out.println("server started successfully");}public static void main(String[] args) {String host = "localhost";int port = 8887;WebSocketServer server = new SimpleServer(new InetSocketAddress(host, port));server.run();}
}

客户端分别给出Web和Java两个版本。

Web版本：

<!DOCTYPE HTML>
<html><head><meta charset="utf-8" /><title>ws</title><style type="text/css"></style><script type="text/javascript">var onOpen = function () {console.log("Socket opened.");socket.send("Hi, Server!");},onClose = function () {console.log("Socket closed.");},onMessage = function (data) {console.log("We get signal:");console.log(data);},onError = function () {console.log("We got an error.");},socket = new WebSocket("ws://127.0.0.1:8887/");pen = lose = r = ssage = onMessage;function sendMessage(){socket.send("Hi, Server,I send Message!");}function left(){socket.send("left");}function right(){socket.send("right");}function up(){socket.send("up");}function down(){socket.send("down");}function enter(){socket.send("enter");}function back(){socket.send("back");}</script>
</head><body><div id="connected"><button onclick="sendMessage()">连接</button></div><div id="left"><button onclick="left()">Left</button></div><div id="right"><button onclick="right()">Right</button></div><div id="up"><button onclick="up()">Up</button></div><div id="down"><button onclick="down()">Down</button></div><div id="enter"><button onclick="enter()">Enter</button></div><div id="back"><button onclick="back()">Back</button></div>
</body></html>

Java版本：

st.ws.utils;import org.java_websocket.client.WebSocketClient;
import org.java_websocket.drafts.Draft;
import org.java_websocket.handshake.ServerHandshake;import java.URI;
import java.URISyntaxException;
import java.nio.ByteBuffer;public class EmptyClient extends WebSocketClient {public EmptyClient(URI serverUri, Draft draft) {super(serverUri, draft);}public EmptyClient(URI serverURI) {super(serverURI);}@Overridepublic void onOpen(ServerHandshake handshakedata) {send("Hello, it is me. Mario :)");System.out.println("new connection opened");}@Overridepublic void onClose(int code, String reason, boolean remote) {System.out.println("closed with exit code " + code + " additional info: " + reason);}@Overridepublic void onMessage(String message) {System.out.println("received message: " + message);}@Overridepublic void onMessage(ByteBuffer message) {System.out.println("received ByteBuffer");}@Overridepublic void onError(Exception ex) {println("an error occurred:" + ex);}public static void main(String[] args) throws URISyntaxException {WebSocketClient client = new EmptyClient(new URI("ws://localhost:8887"));t();}
}

在Android机顶盒端使用的时候，可以将Server放置在一个Service里后台监听运行：

st.ws;import android.app.Service;
t.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.support.annotation.Nullable;import java.io.IOException;
import java.InetSocketAddress;public class ConnectService extends Service implements SimpleServer.MessageListener {private Thread thread;private SimpleServer server;private static MessageListener msgListener;@Nullable@Overridepublic IBinder onBind(Intent intent) {return null;}@Overridepublic void onCreate() {Create();if (thread != null) {thread = null;}thread = new Thread() {@Overridepublic void run() {super.run();server = new SimpleServer(getBaseContext(), new InetSocketAddress(Constants.HOST, Constants.PORT));server.setMessageListener(ConnectService.this);server.run();}};thread.start();}private Handler handler = new Handler() {@Overridepublic void handleMessage(Message msg) {super.handleMessage(msg);if (msgListener != null) {Message(String());}}};@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {StartCommand(intent, flags, startId);}@Overridepublic void onDestroy() {Destroy();if (server != null) {try {server.stop();} catch (IOException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}}}@Overridepublic void onMessage(String text) {Message message = new Message();message.obj = text;handler.sendMessage(message);}public static void setMessageListener(MessageListener messageListener) {msgListener = messageListener;}public interface MessageListener {void onMessage(String message);}
}

机顶盒服务器端接收模拟按键操作：

@Overridepublic void onMessage(String message) {switch (message) {case "left": {sendKeyCode(KeyEvent.KEYCODE_DPAD_LEFT);}break;case "right": {sendKeyCode(KeyEvent.KEYCODE_DPAD_RIGHT);}break;case "up": {sendKeyCode(KeyEvent.KEYCODE_DPAD_UP);}break;case "down": {sendKeyCode(KeyEvent.KEYCODE_DPAD_DOWN);}break;case "enter": {sendKeyCode(KeyEvent.KEYCODE_DPAD_CENTER);}break;case "back": {sendKeyCode(KeyEvent.KEYCODE_BACK);}break;default:Toast.makeText(getBaseContext(), "default：" + message, Toast.LENGTH_SHORT).show();break;}}// 模拟按键发送
private synchronized void sendKeyCode(final int keyCode){new Thread () {public void run() {try {Instrumentation inst = new Instrumentation();inst.sendKeyDownUpSync(keyCode);} catch (Exception e) {Log.e("Exception when sendPointerSync", e.toString());}}}.start();}

并在项目文件清单里加入权限：

<uses-permission android:name="android.permission.INJECT_EVENTS" />

模拟按键核心是Instrumentation这个对象，Instrumentation其实主要用来做测试的，可以模拟所有系统级别按键操作。

默认非系统应用只能模拟控制本应用内（进程内）的按键实践。只有拥有系统应用权限的才可以模拟整个Android系统的事件，包括控制其他的应用操作。

如果采用中转服务器的话，这里采用NodeJS搭建WebSocket服务器端，这里只给出一个简单的Server的搭建示例，后续完善：


var ws = require("nodejs-websocket")// Scream server example: "hi" -> "HI!!!"
var server = ws.createServer(function(conn) {console.log("New connection")("text", function(str) {console.log("Received " + str)conn.UpperCase() + "!!!")})("close", function(code, reason) {console.log("Connection closed")})
}).listen(8001)

本文发布于:2024-02-01 13:41:01，感谢您对本站的认可！

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