Java 代码使用AIDL 技术实现一个服务端可以接收来自多个不同的APP客户端的请求，要区分来自哪一个客户端app的什么类型请求，把请求加入任务栈，任务栈用一个单独的类TaskStack来管理，任务和注册的回调消息绑定。在一个子线程中while循环取出任务栈中的任务，有一个Dispach类来管理任务的分发，在Dispach类中按照请求的优先级同步或者异步的将任务分发执行,还需要考虑任务的优先级、同步或异步处理等问题，执行完成后通过Dispach把消息回调给发请求的那个客户端app，要求线程安全，给出详细的每一个类的代码

以下是实现多个客户端请求的服务端代码，其中包含了任务栈、Dispach类和多个回调消息的注册等功能：

ITaskManager.aidl

interface ITaskManager {
    void registerCallback(ITaskCallback callback);
    void unregisterCallback(ITaskCallback callback);
    void addTask(Task task);
}

ITaskCallback.aidl

interface ITaskCallback {
    void onTaskCompleted(Task task);
}

Task.java

public class Task {
    private String clientId;
    private String type;
    private int priority;
    private boolean isAsync;
    private ITaskCallback callback;

    public Task(String clientId, String type, int priority, boolean isAsync, ITaskCallback callback) {
        this.clientId = clientId;
        this.type = type;
        this.priority = priority;
        this.isAsync = isAsync;
        this.callback = callback;
    }

    // getters and setters
}

TaskStack.java

public class TaskStack {
    private Stack<Task> stack = new Stack<>();
    private ReentrantLock lock = new ReentrantLock();

    public void push(Task task) {
        lock.lock();
        try {
            stack.push(task);
        } finally {
            lock.unlock();
        }
    }

    public Task pop() {
        lock.lock();
        try {
            return stack.isEmpty() ? null : stack.pop();
        } finally {
            lock.unlock();
        }
    }

    public void clear() {
        lock.lock();
        try {
            stack.clear();
        } finally {
            lock.unlock();
        }
    }

    public boolean isEmpty() {
        lock.lock();
        try {
            return stack.isEmpty();
        } finally {
            lock.unlock();
        }
    }
}

Dispach.java

public class Dispach {
    private TaskStack taskStack;
    private ReentrantLock lock = new ReentrantLock();

    public Dispach(TaskStack taskStack) {
        this.taskStack = taskStack;
    }

    public void start() {
        while (true) {
            Task task = taskStack.pop();
            if (task == null) {
                continue;
            }
            if (task.isAsync()) {
                AsyncTask.execute(() -> processTask(task));
            } else {
                processTask(task);
            }
        }
    }

    private void processTask(Task task) {
        // do something based on task
        // ...

        lock.lock();
        try {
            task.getCallback().onTaskCompleted(task);
        } finally {
            lock.unlock();
        }
    }
}

TaskManager.java

public class TaskManager extends Service {
    private TaskStack taskStack = new TaskStack();
    private ConcurrentHashMap<ITaskCallback, String> callbacks = new ConcurrentHashMap<>();
    private ITaskManager.Stub binder = new ITaskManager.Stub() {
        @Override
        public void registerCallback(ITaskCallback callback) throws RemoteException {
            callbacks.put(callback, callback.toString());
        }

        @Override
        public void unregisterCallback(ITaskCallback callback) throws RemoteException {
            callbacks.remove(callback);
        }

        @Override
        public void addTask(Task task) throws RemoteException {
            taskStack.push(task);
        }
    };

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

    @Override
    public boolean onUnbind(Intent intent) {
        callbacks.clear();
        taskStack.clear();
        return super.onUnbind(intent);
    }

    @Override
    public void onDestroy() {
        callbacks.clear();
        taskStack.clear();
        super.onDestroy();
    }
}