1 FDBus简介

FDBus 基于 Socket (TCP 和 Unix domain) 之上的IPC机制, 采用 Google protobuf 做序列化和反序列化。 FDBus还支持字符串形式的名字作为server地址。通过 name server 自动为 server 分配Unix domain 地址和 TCP 端口号, 实现 client 和server 之间用服务名字寻址。一句话描述：FDBus (Fast Distributed Bus) 是一种 IPC 机制, 用于进程间通信。

特点：
分布式：基于TCP socket和Unix Domain socket（UDS），既可用于本地IPC，也支持网络主机之间的IPC；
跨平台：目前已在Windows，Linux和QNX上验证；
高性能：点对点直接通信，不通过中央Hub或Broker转发；
安全性：能够为server的方法调用也事件广播配置不同等级的访问权限，只有权限足够高的client才能特点方法和接收特定事件；
服务名解析：server地址用名字标识，通过name server注册服务和解析名字，从而server可以在全网络任意部署。

2 车载Android设备间通讯

我们知道车载Android设备不止一台，如果我们要在中控和仪表盘这两个Android系统设备之间要进行通信怎么实现呢？同学们思考一下
不同Android设备间的通信已经无法通过Binder、Broadcast、Service来完成，所以我们是否可以参考FDBus通过Socket来进行不同Android设备的通讯呢？下面我们来看看大致思路：

通过Socket+动态代理实现简单的跨设备通讯:

1.YFDBus库中分为IPCNameManager类：实现客户端Socket的管理，动态代理的相关的逻辑；NameServerManager类：服务端的Socket管理。
2.Server模块为服务端，依赖YFDBus库，初始化时服务注册到IPCNameManager中，提供自定义的服务。接收到客户端Socket发送过来的消息后，将该消息解析做出响应返回对应的数据给客户端。
3.Client模块为客户端，依赖YFDBus库，通过Socket实现对Server端的服务发现，确实是数据传输后使用动态代理解析来自Server的响应数据，得到的服务对象。然后通过该对象进行服务调用，确实就是Socket发送数据到Server做处理然后给出响应，来实现服务的发现和调用。

最简单的理解就是：
1.通过Socket客户端向服务端发送消息，实现服务注册、服务发现、服务调用。
2.通过动态代理的方式获取到服务端的类及方法在客户端进行调用。

3 代码实现

3.1 思路图

在这里插入图片描述

3.2 核心代码

3.2.1 项目结构

在这里插入图片描述

下面我们来看看关键的代码：

3.2.2 Client客户端模块

客户端INameServer.java，同服务端的INameServer目的是两边保持一致，在对应模块直接调用。

package com.yvan.nameserver.interfaces;

import com.yvan.yfdbus.annotion.ClassId;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 客户端的服务类（对应服务端com.yvan.nameserver.NameServer类）
 */
@ClassId("com.yvan.nameserver.NameServer")
public interface INameServer {
    /**
     * 速度，能源 信息获取
     *
     * @param userId
     * @param token
     * @return
     */
    SpeedState getSpeed(String userId, String token);
}

客户端SpeedState.java类，是传输的数据类

package com.yvan.nameserver.interfaces;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 客户端速度，能源容量信息类（对应服务端SpeedState类）
 */
public class SpeedState {

    int speed;
    int energy;

    public SpeedState() {
    }

    public SpeedState(int speed, int energy) {
        this.speed = speed;
        this.energy = energy;
    }

    public int getSpeed() {
        return speed;
    }

    public void setSpeed(int speed) {
        this.speed = speed;
    }

    public int getEnergy() {
        return energy;
    }

    public void setEnergy(int energy) {
        this.energy = energy;
    }
}

客户端页面展示ClientActivity.java，主要有：连接服务端、服务发现、服务调用

package com.yvan.client;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

import com.yvan.clent.R;
import com.yvan.nameserver.interfaces.INameServer;
import com.yvan.nameserver.interfaces.SpeedState;
import com.yvan.yfdbus.IPCNameManager;
import com.yvan.yfdbus.NameConfig;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 客户端页面
 */
public class ClientActivity extends AppCompatActivity {

    private static final String TAG = ClientActivity.class.getSimpleName();
    private INameServer iNameServer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        IPCNameManager.getInstance().init(this);
    }

    /**
     * 连接服务端
     *
     * @param view
     */
    public void connect(View view) {
        IPCNameManager.getInstance().connect(NameConfig.IP);
    }

    /**
     * 发现服务
     *
     * @param view
     */
    public void findServer(View view) {
        iNameServer = IPCNameManager.getInstance().getInstance(INameServer.class, "小明的车", "token666");
        Log.i(TAG, "findServer: 服务发现  发现远端设备的服务  ");
    }

    /**
     * 服务调用
     *
     * @param view
     */
    public void invekeServer(View view) {
        Log.i(TAG, "invekeServer: 服务调用 " + iNameServer);
        new Thread() {
            @Override
            public void run() {
                SpeedState speedState = iNameServer.getSpeed("小明的车", "token666");
                Log.i(TAG, "invekeServer: 结果远端设备的速度: " + speedState.getSpeed()
                        + " 远端设备的电池容量: " + speedState.getEnergy());
            }
        }.start();
    }
}

3.2.3 Server服务端模块

INameServer.java、SpeedState.java同客户端，这里不重复贴出来了。
服务端NameServer.java，主要是对INameServer的实现类。

package com.yvan.nameserver;

import android.util.Log;

import com.yvan.nameserver.interfaces.INameServer;
import com.yvan.nameserver.interfaces.SpeedState;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 服务端的服务实现类
 */
public class NameServer implements INameServer {

    private final static String TAG = NameServer.class.getSimpleName();
    private static NameServer sInstance = null;

    public static synchronized NameServer getInstance(String userId, String token) {
        Log.i(TAG, "getInstance:userId  " + userId + " token  " + token);
        if (sInstance == null) {
            sInstance = new NameServer();
        }
        return sInstance;
    }

    @Override
    public SpeedState getSpeed(String userId, String token) {
        return new SpeedState(180, 55);
    }
}

服务端页面展示ServerActivity.java，用于管理服务的启动、服务注册

package com.yvan;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;

import com.yvan.nameserver.NameServer;
import com.yvan.nameserver.R;
import com.yvan.yfdbus.IPCNameManager;
import com.yvan.yfdbus.NameServerManager;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 服务端页面
 */
public class ServerActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 管理服务的启动
        Intent intent = new Intent(this, NameServerManager.class);
        startService(intent);
        // 服务注册
        IPCNameManager.getInstance().register(NameServer.class);
    }
}

3.2.4 YFDBus模块

重点类IPCNameManager.java用于IPC通讯，服务注册、服务发现、服务调用的入口，管理着服务及动态代理。

package com.yvan.yfdbus;

import android.content.Context;
import android.text.TextUtils;
import android.util.Log;

import com.google.gson.Gson;
import com.yvan.yfdbus.annotion.ClassId;
import com.yvan.yfdbus.request.RequestBean;
import com.yvan.yfdbus.request.RequestParamter;

import org.java_websocket.client.WebSocketClient;
import org.java_websocket.handshake.ServerHandshake;

import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.URI;
import java.nio.ByteBuffer;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * @author yvan
 * @date 2023/4/22
 * @description IPC通讯管理类
 */
public class IPCNameManager {

    private static final String TAG = IPCNameManager.class.getSimpleName();
    private NameCenter nameCenter = new NameCenter();
    private static final Gson GSON = new Gson();
    private static final IPCNameManager ourInstance = new IPCNameManager();
    private Context sContext;

    public static IPCNameManager getInstance() {
        return ourInstance;
    }

    public NameCenter getNameCenter() {
        return nameCenter;
    }

    public final Lock lock = new ReentrantLock();
    private String responce = null;

    /**
     * 初始化（客户端）
     *
     * @param context
     */
    public void init(Context context) {
        sContext = context.getApplicationContext();
    }

    /**
     * 服务注册（服务端）
     *
     * @param clazz
     */
    public void register(Class<?> clazz) {
        nameCenter.register(clazz);
    }

    /**
     * WebSocket（客户端给服务端发消息用）
     */
    MyWebSocketClient myWebSocketClient;

    public void connect(String ip) {
        new Thread() {
            @Override
            public void run() {
                connectSocketServer(ip);
            }
        }.start();
    }

    /**
     * 服务发现（客户端）
     *
     * @param clazz
     * @param parameters
     * @param <T>
     * @return
     */
    public <T> T getInstance(Class<T> clazz, Object... parameters) {
        // 实例化  服务发现
        sendRequest(clazz, null, parameters, NameServerManager.TYPE_GET);
        return getProxy(clazz);
    }

    /**
     * 向服务端发送消息（客户端）
     * @param clazz
     * @param method
     * @param parameters
     * @param type
     * @param <T>
     * @return
     */
    public <T> String sendRequest(Class<T> clazz, Method method, Object[] parameters, int type) {
        // socket  协议
        RequestParamter[] requestParamters = null;
        if (parameters != null && parameters.length > 0) {
            requestParamters = new RequestParamter[parameters.length];
            for (int i = 0; i < parameters.length; i++) {
                Object parameter = parameters[i];
                String parameterClassName = parameter.getClass().getName();
                String parameterValue = GSON.toJson(parameter);
                RequestParamter requestParamter = new RequestParamter(parameterClassName, parameterValue);
                requestParamters[i] = requestParamter;
            }
        }
        String className = clazz.getAnnotation(ClassId.class).value();
        String methodName = method == null ? "getInstance" : method.getName();
        RequestBean requestBean = new RequestBean(type, className, methodName, requestParamters);
        String request = GSON.toJson(requestBean);

        synchronized (lock) {
            try {
                // 客户端给服务端发消息
                myWebSocketClient.send(request.getBytes());
                Log.i(TAG, "sendRequest: 锁住线程:" + Thread.currentThread().getName());
                lock.wait();
                Log.i(TAG, "sendRequest: 锁住成功");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        Log.i(TAG, "sendRequest: 唤醒线程");
        if (!TextUtils.isEmpty(responce)) {
            String data1 = responce;
            responce = null;
            return data1;
        }
        return null;
    }

    /**
     * 动态代理
     * @param clazz
     * @param <T>
     * @return
     */
    private <T> T getProxy(Class<T> clazz) {
        ClassLoader classLoader = sContext.getClassLoader();
        return (T) Proxy.newProxyInstance(classLoader, new Class<?>[]{clazz},
                new NameServerInvokeHandler(clazz));
    }

    /**
     * 连接服务端
     * @param ip
     */
    private void connectSocketServer(String ip) {
        try {
            URI url = new URI(ip + NameConfig.IP_PORT);
            myWebSocketClient = new MyWebSocketClient(url);
            myWebSocketClient.connect();
            Log.i(TAG, "connect: 连接 ");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 客户端Socket
     */
    class MyWebSocketClient extends WebSocketClient {
        public MyWebSocketClient(URI serverUri) {
            super(serverUri);
            Log.i(TAG, "MyWebSocketClient create serverUri:" + serverUri);
        }

        @Override
        public void onOpen(ServerHandshake handshakedata) {
            Log.i(TAG, "onOpen: ");
        }

        @Override
        public void onMessage(String message) {
            Log.i(TAG, "onMessage: " + message);
        }

        public void onMessage(ByteBuffer message) {
            byte[] buf = new byte[message.remaining()];
            message.get(buf);
            String data = new String(buf);
            Log.i(TAG, "客户端收到信息 onMessage: " + data);
            responce = data;
            synchronized (lock) {
                try {
                    lock.notify();
                } catch (Exception e) {
                    Log.e(TAG, "onMessage: 锁异常: " + e.getMessage());
                }
            }
        }

        @Override
        public void onClose(int code, String reason, boolean remote) {
            Log.i(TAG, "onClose: code: " + code + ", reason: " + reason + ", remote: " + remote);
        }

        @Override
        public void onError(Exception ex) {
            Log.e(TAG, "onError: " + ex.getMessage());
        }
    }
}

动态代理类NameServerInvokeHandler.java

package com.yvan.yfdbus;

import android.text.TextUtils;
import android.util.Log;

import com.google.gson.Gson;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 服务代理方法类
 */
public class NameServerInvokeHandler implements InvocationHandler {
    private static final String TAG = NameServerInvokeHandler.class.getSimpleName();
    private static final Gson GSON = new Gson();
    private Class clazz;

    public NameServerInvokeHandler(Class clazz) {
        this.clazz = clazz;
    }

    @Override
    public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
        if (method.getName().contains("toString")) {
            return "proxy";
        }
        Log.i(TAG, "invoke: " + method.getName());
        // 发送请求
        String data = IPCNameManager.getInstance().sendRequest(clazz, method, objects, NameServerManager.TYPE_INVOKE);
        Log.i(TAG, "invoke: data " + data);
        if (!TextUtils.isEmpty(data)) {
            Object object = GSON.fromJson(data, method.getReturnType());
            return object;
        }
        return null;
    }
}

服务管理类NameServerManager.java，用于处理服务发现和处理服务调用给客户端响应

package com.yvan.yfdbus;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

import androidx.annotation.Nullable;

import com.google.gson.Gson;
import com.yvan.yfdbus.request.RequestBean;
import com.yvan.yfdbus.request.RequestParamter;

import org.java_websocket.WebSocket;
import org.java_websocket.handshake.ClientHandshake;
import org.java_websocket.server.WebSocketServer;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 服务端管理类
 */
public class NameServerManager extends Service {

    private static final String TAG = NameServerManager.class.getSimpleName();

    private final Gson gson = new Gson();

    //服务发现
    public static final int TYPE_GET = 1;
    //服务调用
    public static final int TYPE_INVOKE = 2;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Log.i(TAG, "onCreate: 开始 ");
        new Thread(new TcpServer()).start();
    }

    private class TcpServer implements Runnable {
        @Override
        public void run() {
            // 服务端开启SocketServer，等待客户端的请求
            SocketServer socketServer = new SocketServer();
            socketServer.start();
        }
    }

    class SocketServer extends WebSocketServer {

        public SocketServer() {
            super(new InetSocketAddress(NameConfig.IP_PORT));
        }

        @Override
        public void onOpen(WebSocket conn, ClientHandshake handshake) {
            Log.i(TAG, "onOpen: " + conn.getRemoteSocketAddress().getAddress().getHostAddress());
        }

        @Override
        public void onClose(WebSocket conn, int code, String reason, boolean remote) {
            Log.i(TAG, "onClose: " + conn.getRemoteSocketAddress().getAddress().getHostAddress()
                    + ", code:" + code
                    + ", reason:" + reason
                    + ", remote:" + remote);
        }

        @Override
        public void onMessage(WebSocket conn, String message) {
        }

        @Override
        public void onMessage(WebSocket conn, ByteBuffer message) {
            Log.i(TAG, "onMessage: " + conn.getRemoteSocketAddress().getAddress().getHostAddress());
            byte[] buf = new byte[message.remaining()];
            message.get(buf);
            String request = new String(buf);
            Log.i(TAG, "onMessage 接收到客户端消息: " + request);
            String responce = dealRequest(request);
            Log.i(TAG, "onMessage 向客户端发送数据: " + responce);
            // 服务端 向 客户端 发送响应
            conn.send(responce.getBytes());
        }

        @Override
        public void onError(WebSocket conn, Exception ex) {
            Log.e(TAG, "onError: " + conn.getRemoteSocketAddress().getAddress().getHostAddress()
                    + ", ex:" + ex);
        }

        @Override
        public void onStart() {
            Log.i(TAG, "onStart: ");
        }
    }

    /**
     * 服务端处理客户端发送过来的消息，返回响应
     *
     * @param request
     * @return
     */
    String dealRequest(String request) {
        RequestBean requestBean = gson.fromJson(request, RequestBean.class);
        int type = requestBean.getType();
        //服务发现， 服务初始化
        switch (type) {
            case TYPE_INVOKE:
                Object object = IPCNameManager.getInstance().getNameCenter().getObject(requestBean.getClassName());
                Method tempMethod = IPCNameManager.getInstance().getNameCenter().getMethod(requestBean);
                Object[] mParameters = makeParameterObject(requestBean);
                try {
                    Object result = tempMethod.invoke(object, mParameters);
                    String data = gson.toJson(result);
                    return data;
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                } catch (InvocationTargetException e) {
                    e.printStackTrace();
                }
                break;
            case TYPE_GET:
                Method method = IPCNameManager.getInstance().getNameCenter().getMethod(requestBean);
                Object[] parameters = makeParameterObject(requestBean);
                try {
                    Object object1 = method.invoke(null, parameters);
                    IPCNameManager.getInstance().getNameCenter().putObject(requestBean.getClassName(), object1);
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                } catch (InvocationTargetException e) {
                    e.printStackTrace();
                }
                return "success";
        }
        return null;
    }

    /**
     * 获取方法参数的值
     *
     * @param requestBean
     * @return
     */
    private Object[] makeParameterObject(RequestBean requestBean) {
        Object[] mParameters = null;
        RequestParamter[] requestParamters = requestBean.getRequestParamters();
        if (requestParamters != null && requestParamters.length > 0) {
            mParameters = new Object[requestBean.getRequestParamters().length];
            for (int i = 0; i < requestParamters.length; i++) {
                RequestParamter requestParamter = requestParamters[i];
                Class<?> clazz = IPCNameManager.getInstance().getNameCenter().getClassType(requestParamter.getParameterClassName());
                mParameters[i] = gson.fromJson(requestParamter.getParameterValue(), clazz);
            }

        } else {
            mParameters = new Object[0];
        }
        return mParameters;
    }

}

NameCenter.java类个方法管理中心

package com.yvan.yfdbus;

import com.yvan.yfdbus.request.RequestBean;
import com.yvan.yfdbus.request.RequestParamter;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author yvan
 * @date 2023/4/22
 * @description 类和方法管理中心
 */
public class NameCenter {

    /**
     * 类集合
     */
    private ConcurrentHashMap<String, Class<?>> mClassMap;

    /**
     * 方法集合
     */
    private ConcurrentHashMap<String, ConcurrentHashMap<String, Method>> mAllMethodMap;

    /**
     * 方法参数值
     */
    private final ConcurrentHashMap<String, Object> mInstanceObjectMap;

    public NameCenter() {
        mClassMap = new ConcurrentHashMap<String, Class<?>>();
        mAllMethodMap = new ConcurrentHashMap<String, ConcurrentHashMap<String, Method>>();
        mInstanceObjectMap = new ConcurrentHashMap<String, Object>();
    }

    public void register(Class clazz) {
        mClassMap.put(clazz.getName(), clazz);
        Method[] methods = clazz.getDeclaredMethods();
        for (Method method : methods) {
            ConcurrentHashMap<String, Method> map = mAllMethodMap.get(clazz.getName());
            if (map == null) {
                map = new ConcurrentHashMap<String, Method>();
                mAllMethodMap.put(clazz.getName(), map);
            }
            // java重载   方法名+参数
            String key = getMethodParameters(method);
            map.put(key, method);
        }
    }

    public void putObject(String className, Object instance) {
        mInstanceObjectMap.put(className, instance);
    }

    public Object getObject(String className) {
        return mInstanceObjectMap.get(className);
    }

    public Method getMethod(RequestBean requestBean) {
        ConcurrentHashMap<String, Method> map = mAllMethodMap.get(requestBean.getClassName());
        if (map != null) {
            String key = getMethodParameters(requestBean);
            return map.get(key);
        }
        return null;
    }

    public Class<?> getClassType(String parameterClassName) {
        try {
            Class clazz = Class.forName(parameterClassName);
            return clazz;
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 拼装方法（方法名-参数类型）
     *
     * @param requestBean
     * @return
     */
    public static String getMethodParameters(RequestBean requestBean) {
        List<String> parameterClassName = new ArrayList<>();
        for (RequestParamter c : requestBean.getRequestParamters()) {
            parameterClassName.add(c.getParameterClassName());
        }
        return getMethodParameters(requestBean.getMethodName(), parameterClassName);
    }

    /**
     * 拼装方法（方法名-参数类型）
     *
     * @param method
     * @return
     */
    public static String getMethodParameters(Method method) {
        List<String> parameterClassName = new ArrayList<>();
        for (Class<?> c : method.getParameterTypes()) {
            parameterClassName.add(c.getName());
        }
        return getMethodParameters(method.getName(), parameterClassName);
    }

    /**
     * 拼装方法（方法名-参数类型）
     *
     * @param methodName
     * @param parameterClassName
     * @return
     */
    public static String getMethodParameters(String methodName, List<String> parameterClassName) {
        // 方法签名
        StringBuilder result = new StringBuilder();
        result.append(methodName);
        int size = parameterClassName.size();
        if (size == 0) {
            return result.toString();
        }
        for (int i = 0; i < size; ++i) {
            result.append("-").append(parameterClassName.get(i));
        }
        return result.toString();
    }

}