android - 与 Arduino + Android 的蓝牙通信

Question

我试图将字节从我的 android 发送到我的 arduino 以使其关闭/打开连接到它的 led。当我打开我的 Android 应用程序时，它会立即转到“未响应消息”并关闭。

这是安卓代码:

package com.example.arduino;

import java.io.IOException;
import java.io.OutputStream;
import java.util.UUID;

import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {

Button turnOn , turnOff;
BluetoothAdapter btAdapter;
OutputStream outStream;
BluetoothSocket btSocket;
byte one;
byte two;
BluetoothDevice btDevice;
String address = "40:98:4E:37:4E:51";
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

@SuppressWarnings("static-access")
@SuppressLint("ShowToast") @Override

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    turnOn = (Button) findViewById(R.id.On);
    turnOff = (Button) findViewById(R.id.Off); 
    one = 0;
    two = 1;
    btAdapter = BluetoothAdapter.getDefaultAdapter();

    try {
        outStream = btSocket.getOutputStream();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

    btDevice = btAdapter.getRemoteDevice(address);

    try {
        btSocket = btDevice.createRfcommSocketToServiceRecord(uuid);
        btSocket.connect();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

    if(btDevice.ACTION_ACL_CONNECTED != null){ //Suppressed.
        Toast.makeText(getBaseContext(), "Connected!", Toast.LENGTH_SHORT).show(); //Suppressed.
    }


    turnOn.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            ledOn();
        }

        private void ledOn() {
            // TODO Auto-generated method stub
            try {
                outStream.write(one);
                outStream.flush();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                outStream.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    });

    turnOff.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            ledOff();
        }

        private void ledOff() {
            // TODO Auto-generated method stub
            try {
                outStream.write(two);
                outStream.flush();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                outStream.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    });

}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}  
}

日志:

10-17 23:32:05.269: W/dalvikvm(21770): threadid=1: thread exiting with uncaught    exception (group=0x40c7ea08)
10-17 23:32:05.269: E/AndroidRuntime(21770): FATAL EXCEPTION: main
10-17 23:32:05.269: E/AndroidRuntime(21770): java.lang.RuntimeException: Unable to  start activity ComponentInfo{com.example.arduino/com.example.arduino.MainActivity}: java.lang.NullPointerException
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2463)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2520)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.ActivityThread.access$600(ActivityThread.java:162)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1366)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.os.Handler.dispatchMessage(Handler.java:99)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.os.Looper.loop(Looper.java:158)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.ActivityThread.main(ActivityThread.java:5751)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at java.lang.reflect.Method.invokeNative(Native Method)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at java.lang.reflect.Method.invoke(Method.java:511)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1083)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:850)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at dalvik.system.NativeStart.main(Native Method)
10-17 23:32:05.269: E/AndroidRuntime(21770): Caused by: java.lang.NullPointerException
10-17 23:32:05.269: E/AndroidRuntime(21770):    at com.example.arduino.MainActivity.onCreate(MainActivity.java:44)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.Activity.performCreate(Activity.java:5165)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1103)
10-17 23:32:05.269: E/AndroidRuntime(21770):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2419)
10-17 23:32:05.269: E/AndroidRuntime(21770):    ... 11 more

Answer 1

您正在使用初始化之前的 btSocket 变量。在你的 onCreate 方法上，尝试把这个:

 try {
        outStream = btSocket.getOutputStream();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

在此之后:

btDevice = btAdapter.getRemoteDevice(address);

try {
    btSocket = btDevice.createRfcommSocketToServiceRecord(uuid);
    btSocket.connect();
} catch (IOException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}