ble信標發射機應用程序運行后立即關閉

Question

我正在嘗試創建一個應用以從android 5.0設備傳輸信標，但出現此錯誤

{09-07 10:23:45.184 3057-3057/com.example.mohamed_pc.test2 E/AndroidRuntime: FATAL EXCEPTION: main
                                                                            Process: com.example.mohamed_pc.test2, PID: 3057
                                                                            java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mohamed_pc.test2/com.example.mohamed_pc.test2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.bluetooth.le.BluetoothLeAdvertiser android.bluetooth.BluetoothAdapter.getBluetoothLeAdvertiser()' on a null object reference
                                                                                at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
                                                                                at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                                                at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                                                at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                                                at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                at android.os.Looper.loop(Looper.java:148)
                                                                                at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                                at java.lang.reflect.Method.invoke(Native Method)
                                                                                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                                             Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.bluetooth.le.BluetoothLeAdvertiser android.bluetooth.BluetoothAdapter.getBluetoothLeAdvertiser()' on a null object reference
                                                                                at com.example.mohamed_pc.test2.MainActivity.onCreate(MainActivity.java:31)
                                                                                at android.app.Activity.performCreate(Activity.java:6237)
                                                                                at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
                                                                                at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
                                                                                at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
                                                                                at android.app.ActivityThread.-wrap11(ActivityThread.java) 
                                                                                at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
                                                                                at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                                at android.os.Looper.loop(Looper.java:148) 
                                                                                at android.app.ActivityThread.main(ActivityThread.java:5417) 
                                                                                at java.lang.reflect.Method.invoke(Native Method) 
                                                                                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                                                                                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) }

代碼如下

package com.example.mohamed_pc.test2;


import android.bluetooth.BluetoothAdapter;
import android.bluetooth.le.AdvertiseCallback;
import android.bluetooth.le.AdvertiseData;
import android.bluetooth.le.AdvertiseSettings;
import android.bluetooth.le.BluetoothLeAdvertiser;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import java.nio.ByteBuffer;
import java.util.UUID;



public class MainActivity extends AppCompatActivity {
   private BluetoothAdapter mBluetoothAdapter;
    private BluetoothLeAdvertiser mBluetoothLeAdvertiser;
   private AdvertiseData mAdvertiseData;
    private AdvertiseSettings mAdvertiseSettings;
    private AdvertiseCallback mAdvertiseCallback;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
       mBluetoothLeAdvertiser = mBluetoothAdapter.getBluetoothLeAdvertiser();
    }

    public void buttonOnClick(View v) {
// do something when the button is clicked
        Button button=(Button) v;
        ((Button) v).setText("clicked");
        setAdvertiseData();
        setAdvertiseSettings();
        mBluetoothLeAdvertiser.startAdvertising(mAdvertiseSettings, mAdvertiseData, mAdvertiseCallback);

    }

   protected void setAdvertiseData() {
        AdvertiseData.Builder mBuilder = new AdvertiseData.Builder();
        ByteBuffer mManufacturerData = ByteBuffer.allocate(24);
        byte[] uuid = getIdAsByte(UUID.fromString("0CF052C297CA407C84F8B62AAC4E9020"));
        mManufacturerData.put(0, (byte)0xBE); // Beacon Identifier
        mManufacturerData.put(1, (byte)0xAC); // Beacon Identifier
        for (int i=2; i<=17; i++) {
            mManufacturerData.put(i, uuid[i-2]); // adding the UUID
        }
        mManufacturerData.put(18, (byte)0x00); // first byte of Major
        mManufacturerData.put(19, (byte)0x09); // second byte of Major
        mManufacturerData.put(20, (byte)0x00); // first minor
        mManufacturerData.put(21, (byte)0x06); // second minor
        mManufacturerData.put(22, (byte)0xB5); // txPower
        mBuilder.addManufacturerData(224, mManufacturerData.array()); // using google's company ID
        mAdvertiseData = mBuilder.build();
    }
    protected void setAdvertiseSettings() {
        AdvertiseSettings.Builder mBuilder = new AdvertiseSettings.Builder();
        mBuilder.setAdvertiseMode(AdvertiseSettings.ADVERTISE_MODE_LOW_POWER);
        mBuilder.setConnectable(false);
        mBuilder.setTimeout(0);
        mBuilder.setTxPowerLevel(AdvertiseSettings.ADVERTISE_TX_POWER_MEDIUM);
        mAdvertiseSettings = mBuilder.build();
    }
    public static byte[] getIdAsByte(java.util.UUID uuid)
    {
        ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
        bb.putLong(uuid.getMostSignificantBits());
        bb.putLong(uuid.getLeastSignificantBits());
        return bb.array();
    }

}

Answer 1

mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

給你空值 檢查許可以及是否啟用了藍牙

Answer 2

更改了格式：

UUID.fromString("0CF052C297CA407C84F8B62AAC4E9020")

通過：

UUID.fromString("0CF052C2-97CA-407C-84F8-B62AAC4E9020");