Java 状态模式中的破坏封装

问题描述

我已经在 J​​ava 中为我的套接字库实现了状态模式。 我简化了代码以减小大小并提高可读性只是为了演示问题。 我不知道如何通过状态类来封装 Socket 类的使用。 我写了评论以更好地理解问题。 所以，有一个示例代码：

package com.test;

enum ConnectionAttemptResult {
    ConnectionAttemptStarted,AlreadyInProgress,AlreadyConnected,UnableToCreateSocket,UnableToConnectSocket,UnableToCreateReadEvent
}

class SocketAddress {
    static SocketAddress LocalhostPort(int port) {
        // Code removed.
        return new SocketAddress();
    }
}

class Socket {
    private State currentState;

    Socket() {
        this.currentState = new NotActiveState(this);
    }

    public ConnectionAttemptResult Connect(SocketAddress remoteAddress) {
        return this.currentState.Connect(remoteAddress);
    }

    // Socket class is external and will be used by user.
    // So further methods must be private because they are internal.
    // Calling these methods by a user may broke class functionality.
    // But I can't make them private because then states couldn't access them.
    public void SwitchState(State newState) {
        this.currentState = newState;
    }

    // I removed a lot of code of this class to simplify the code.
    public boolean CreateSocket() {
        // Code removed.
        return true;
    }

    public boolean ConnectSocket(SocketAddress remoteAddress) {
        // Code removed.
        return true;
    }

    public boolean CreateReadEvent() {
        // Code removed.
        return true;
    }
}

abstract class State {
    protected Socket socket;

    State(Socket socket) {
        this.socket = socket;
    }

    public abstract ConnectionAttemptResult Connect(SocketAddress remoteAddress);
}

class NotActiveState extends State {
    NotActiveState(Socket socket) {
        super(socket);
    }

    @Override
    public ConnectionAttemptResult Connect(SocketAddress remoteAddress) {
        if (!socket.CreateSocket())
            return ConnectionAttemptResult.UnableToCreateSocket;

        if (!socket.ConnectSocket(remoteAddress))
            return ConnectionAttemptResult.UnableToConnectSocket;

        if (!socket.CreateReadEvent())
            return ConnectionAttemptResult.UnableToCreateReadEvent;

        socket.SwitchState(new ConnectingState(socket));
        return ConnectionAttemptResult.ConnectionAttemptStarted;
    }
}

class ConnectingState extends State {
    ConnectingState(Socket socket) {
        super(socket);
    }

    @Override
    public ConnectionAttemptResult Connect(SocketAddress remoteAddress) {
        return ConnectionAttemptResult.AlreadyInProgress;
    }
}

class ConnectedState extends State {
    ConnectedState(Socket socket) {
        super(socket);
    }

    @Override
    public ConnectionAttemptResult Connect(SocketAddress remoteAddress) {
        return ConnectionAttemptResult.AlreadyConnected;
    }
}

class Main {
    public static void main(String[] args) {
        Socket socket = new Socket();
        socket.Connect(SocketAddress.LocalhostPort(9898));

        // But I also can call internal methods and break the class functionality,because now they are public.
        socket.CreateSocket();
        socket.CreateReadEvent();
    }
}

我的错误在哪里？ 开发人员通常如何实现这种模式保存封装？ 希望得到您的帮助！ 提前致谢！

解决方法

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