android - 2个关于Android套接字编程的问题

Question

我采用了在 Internet 上找到的套接字编程示例，并尝试为支持以太网的 Arduino 服务器构建我自己的 Android 客户端。但是我有两个问题。首先，我的主要 Activity 的代码:

package com.domiflichi.TesterProject;

import java.io.BufferedWriter; // output
import java.io.BufferedReader; // input
import java.io.InputStreamReader; // input
import java.io.OutputStreamWriter; // output
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;

import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;







public class TesterProjectMain extends Activity implements OnClickListener
{

private Button connectPhones;

private TextView myTextView; // represents the 'status text'

private String serverIpAddress = "";

private boolean connected = false;


private Handler handler = new Handler();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.client);


connectPhones = (Button) findViewById(R.id.connect_phones);

connectPhones.setOnClickListener(connectListener);
connectPhones.setOnClickListener(this);



myTextView = (TextView) findViewById(R.id.text1);

}



// This was created when using the 'implements OnClickListener' in the class
public void onClick(View v) {
if (v.getId() == R.id.connect_phones) {
if (!connected) {
serverIpAddress = "192.168.0.178";
if (!serverIpAddress.equals("")) {
Thread cThread = new Thread(new ClientThread());
cThread.start();
connectPhones.setEnabled(false); // Once the button is pressed, disable it. :)
}
}

} else if (v.getId() == R.id.status_req) {
// CODE HERE FOR STATUS REQUEST BUTTON?

} else if (v.getId() == R.id.cmd_toggle) {
// CODE HERE FOR TOGGLE DOOR BUTTON?

} else if (v.getId() == R.id.cmd_crack) {
// CODE HERE FOR CRACK BUTTON?

} else if (v.getId() == R.id.disconnect) {
// CODE HERE FOR DISCONNECT BUTTON?

}
}





public class ClientThread implements Runnable {

public void run() {
try {
InetAddress serverAddr = InetAddress.getByName(serverIpAddress);
Log.d("ClientActivity", "C: Connecting...");
Socket socket = new Socket(serverAddr, 23);
connected = true;

while (connected) {
try {
Log.d("ClientActivity", "C: Sending command.");
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
out.println("mypass*");
Log.d("ClientActivity", "C: Sent.");





BufferedReader r = new BufferedReader(new InputStreamReader(socket.getInputStream()));
final StringBuilder total = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
total.append(line);
Log.d("Server response", line.toString());

}





handler.post(new Runnable() {
public void run() {


if (total.toString().contentEquals("status:open")) {

myTextView.setText(R.string.status_open);
} else {
myTextView.setText(R.string.status_closed);
}

}
});







connected = false;

} catch (Exception e) {
Log.e("ClientActivity", "S: Error", e);
}

}


socket.close();
Log.d("ClientActivity", "C: Closed.");


} catch (Exception e) {
Log.e("ClientActivity", "C: Error", e);
connected = false;
}
}
}
}

所以我的两个问题是:

1. 我不知道如何让我的按钮与我向服务器发送命令的套接字交互。连接后，我有 (4) 个按钮需要通过套接字发送各种命令(它在一个单独的线程中运行，通过单击我拥有的“连接”按钮启动)。 (寻找“//CODE HERE FOR STATUS REQUEST BUTTON？”评论，我希望将各种按钮的代码放在哪里)

2. 我需要移动

   'handler.post(new Runnable() {'

进入我的主循环的代码块:

(while ((line = r.readLine()) != null) {
total.append(line);
Log.d("Server response", line.toString());
}

但是，当我这样做并更改时:

if (total.toString().contentEquals("status:open")) {

到

if (line.toString().contentEquals("status:open")) {

(因为我实际上一次只想读一行)，Eclipse 提示以下消息:不能在不同方法中定义的内部类中引用非最终变量行

如果我尝试更改上面的行...: 弦线；至 静态字符串行；

Eclipse 在下一行提示:

while ((line = r.readLine()) != null) {

说:最终的局部变量行可能已经被赋值

我什至不敢相信我已经走到这一步，因为我是一个完全的新手，但现在我碰壁了。

Answer 1

对于你的第二个问题:创建一个新的 final 用于你的 runnable

while ((line = r.readLine()) != null) {
    total.append(line);
    Log.d("Server response", line.toString());
    final String status = line;
    handler.post(new Runnable() {
        public void run() {
            if (status.contentEquals("status:open")) {
                myTextView.setText(R.string.status_open);
            } else {
                myTextView.setText(R.string.status_closed);
            }
        }
    });
}

第一个问题:你选择了一项相当复杂的任务。您的线程需要检查您从外部设置的某些条件，以便线程可以决定下一步需要做什么。从这些按钮你可以改变例如一个AtomicInteger只要无事可做就为 0，如果你想开灯则为 1，2 ...等等

您的线程将检查该值，将其重置为 0(在一个 .getAndSet(0) 中)并执行他应该执行的操作。

编辑:这就是它的样子

线程

public class LoopingNetworkThread extends Thread {
    public static final int TASK_END = -1;
    public static final int TASK_NOOP = 0;
    public static final int TASK_LIGHTS_ON = 1;
    public static final int TASK_LIGHTS_OFF = 2;

    private final AtomicInteger mNextTask = new AtomicInteger(0);

    /* Executed in this threads context */
    @Override
    public void run() {
        openSocket();
        int currentTask;
        while ((currentTask = mNextTask.getAndSet(TASK_NOOP)) != TASK_END) {
            switch (currentTask) {
                case TASK_LIGHTS_ON:
                    sendLightsOn();
                    break;
                case TASK_LIGHTS_OFF:
                    sendLightsOff();
                    break;
                default:
                    keepAlive();
                    break;
            }
            // depending on your requirements sleep some time inbetween.
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                // ignore
            }
        }
        // the while ends once you set task to TASK_END
        closeSocket();
    }

    private void openSocket() {  }
    private void closeSocket() {  }
    private void keepAlive() {  }
    private void sendLightsOn() {  }
    private void sendLightsOff() {  }

    /* Executed in a different thread context */
    public int setNextTask(int task){
        // return what we overwrite here, maybe that is useful.
        return mNextTask.getAndSet(task);
    }
}

您的 Activity

public class YourActivity extends Activity {
    private LoopingNetworkThread mThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mThread = new LoopingNetworkThread();
        View startButton = findViewById(R.id.button1);
        View stopButton = findViewById(R.id.button2);
        startButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                mThread.start();
            }
        });
        stopButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                mThread.setNextTask(LoopingNetworkThread.TASK_END);
            }
        });
    }
}