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如何與USB設備通信？

2012-04-17 98 views
12

我試圖建立作爲主機的USB通信。我正在按照這裏的例子http://developer.android.com/guide/topics/usb/host.html，但我無法得到這個工作。這裏是我的代碼：如何與USB設備通信？

private static final String ACTION_USB_PERMISSION = "com.multitools.andres.LCView"; 
    UsbDevice device; 
    //Pide permisos al usuario para comunicacion con el dispositivo USB 
    private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() { 
     @Override 
     public void onReceive(Context context, Intent intent) { 
      String action = intent.getAction(); 
      if (ACTION_USB_PERMISSION.equals(action)) { 
       synchronized (this) { 
        UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE); 
        if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) { 
         if(device != null){ 
          //call method to set up device communication 
         } 
        } 
        else { 
         Log.d(TAG, "permission denied for device " + device); 
        } 
       } 
      } 
     } 
    }; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     if(DEBUG) Log.i(TAG, "onCreate() -> MainMenu"); 

     actionBar = getActionBar();      //obtengo el ActionBar 
     actionBar.setDisplayHomeAsUpEnabled(true);  //el icono de la aplicacion funciona como boton HOME 
     //Menu 
     setListAdapter(new ArrayAdapter<String>(MainMenu.this, android.R.layout.simple_list_item_1, MenuNames)); 

     //USB 
     if(DEBUG) Log.i(TAG, "Setting UsbManager -> MainMenu"); 
     UsbManager mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE); 
     PendingIntent mPermissionIntent; 

     if(DEBUG) Log.i(TAG, "Setting PermissionIntent -> MainMenu"); 
     mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0); 
     if(DEBUG) Log.i(TAG, "Setting IntentFilter -> MainMenu"); 
     IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION); 
     if(DEBUG) Log.i(TAG, "Setting registerReceiver -> MainMenu"); 
     registerReceiver(mUsbReceiver, filter); 
     if(DEBUG) Log.i(TAG, "Setting requestPermission -> MainMenu"); 
     mUsbManager.requestPermission(device, mPermissionIntent); 

    }

我得到了部隊關閉對話框，當我取消對該行mUsbManager.requestPermission(device, mPermissionIntent);如果我評論它，我不親近力，但它不工作。我認爲這個問題是：

private static final String ACTION_USB_PERMISSION = "com.multitools.andres.LCView";

在谷歌的例子是爲：

private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";

但我不知道到底是什麼我已經把那裏，我無法找到任何解釋。我必須放在那裏或我的錯誤在哪裏？這裏是logcat的時候我開始我的應用程序我得到：

04-17 00:57:50.944: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:51.331: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:51.981: I/(1362): onCreate() -> MainMenu 
04-17 00:57:52.013: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:52.151: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:52.570: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:52.731: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:53.122: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:53.231: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:53.390: I/(1362): Setting UsbManager -> MainMenu 
04-17 00:57:53.451: I/(1362): Setting PermissionIntent -> MainMenu 
04-17 00:57:53.470: I/(1362): Setting IntentFilter -> MainMenu 
04-17 00:57:53.470: I/(1362): Setting registerReceiver -> MainMenu 
04-17 00:57:53.511: I/(1362): Setting requestPermission -> MainMenu 
04-17 00:57:53.660: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:53.791: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:54.311: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:54.401: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:54.531: I/(1362): onCreateOptionsMenu() -> MainMenu 
04-17 00:57:54.683: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:54.772: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:55.186: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:55.291: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:55.661: I/dalvikvm(1362): threadid=3: reacting to signal 3 
04-17 00:57:55.751: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 
04-17 00:57:55.791: D/gralloc_goldfish(1362): Emulator without GPU emulation detected. 
04-17 01:11:47.323: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:47.720: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:48.124: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:48.291: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:48.452: I/(1459): onCreate() -> MainMenu 
04-17 01:11:48.691: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:48.813: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:49.172: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:49.321: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:49.653: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:49.821: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:49.901: I/(1459): Setting UsbManager -> MainMenu 
04-17 01:11:49.931: I/(1459): Setting PermissionIntent -> MainMenu 
04-17 01:11:50.021: I/(1459): Setting IntentFilter -> MainMenu 
04-17 01:11:50.031: I/(1459): Setting registerReceiver -> MainMenu 
04-17 01:11:50.051: I/(1459): Setting requestPermission -> MainMenu 
04-17 01:11:50.071: D/AndroidRuntime(1459): Shutting down VM 
04-17 01:11:50.133: W/dalvikvm(1459): threadid=1: thread exiting with uncaught exception (group=0x409c01f8) 
04-17 01:11:50.231: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:50.331: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:50.401: E/AndroidRuntime(1459): FATAL EXCEPTION: main 
04-17 01:11:50.401: E/AndroidRuntime(1459): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.multitools.andres/com.multitools.andres.MainMenu}: java.lang.NullPointerException 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.ActivityThread.access$600(ActivityThread.java:123) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.os.Looper.loop(Looper.java:137) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.ActivityThread.main(ActivityThread.java:4424) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at dalvik.system.NativeStart.main(Native Method) 
04-17 01:11:50.401: E/AndroidRuntime(1459): Caused by: java.lang.NullPointerException 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.os.Parcel.readException(Parcel.java:1333) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.os.Parcel.readException(Parcel.java:1281) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.hardware.usb.IUsbManager$Stub$Proxy.requestDevicePermission(IUsbManager.java:535) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.hardware.usb.UsbManager.requestPermission(UsbManager.java:361) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at com.multitools.andres.MainMenu.onCreate(MainMenu.java:80) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.Activity.performCreate(Activity.java:4465) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 
04-17 01:11:50.401: E/AndroidRuntime(1459):  ... 11 more 
04-17 01:11:50.751: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:50.851: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:51.331: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:51.403: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 
04-17 01:11:51.774: I/dalvikvm(1459): threadid=3: reacting to signal 3 
04-17 01:11:51.961: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt'

謝謝你:)

來源

2012-04-17 Andres

+0

'MainMenu.java'文件的第80行是什麼？該行似乎在拋出一個'NullPointerException'。 – chandsie 2012-04-17 01:19:38

+0

mUsbManager.requestPermission（device，mPermissionIntent）;如果評論它的應用程序沒有FC，我認爲是因爲私有靜態最終字符串的行ACTION_USB_PERMISSION =「com.multitools.andres.LCView」;因爲我不知道該放什麼 – Andres 2012-04-17 01:26:11

回答

17

該字符串只是一個標記，以便你認識到，當你調用registerReceiver(mUsbReceiver, filter);時，返回的意圖。這不是問題。

我認爲這個問題是在這裏：

UsbManager mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);

這條線應該接受您的USB經理，但據我記得不是所有手機都支持Android USB附件API。此行可能只是將null分配給mUsbManager，然後當您在代碼中進一步調用方法時，會導致您NullPointerException。在打電話之前試着檢查是否不是null。

欲瞭解更多信息，結帳以下鏈接：

  1. http://developer.android.com/guide/topics/usb/index.html
  2. http://developer.android.com/guide/topics/usb/accessory.html

編輯：

我想我看到現在的問題是什麼。你是對的，這不是USB管理器。這是UsbDevice對象（device）。它永遠不會在代碼中的任何地方初始化。在這一行：

mUsbManager.requestPermission(device, mPermissionIntent);

你基本上發射過的意圖，詢問用戶是否也沒關係讓你由UsbDevice對象device表示的設備正常工作。但是，當此呼叫被觸發時，device尚未初始化（因此其默認值爲null）。因此，當您嘗試請求權限時，您最終得到的是NullPointerException而不是預期的結果。要解決此問題，您需要確定要連接的設備並將其分配給device。查看here，在「枚舉設備」下找出不同的方法來做到這一點。一種方法，如果你知道你要連接到該設備的名稱，是您檢索USB管理後做出以下電話：

HashMap<String, UsbDevice> deviceList = mUsbManager.getDeviceList(); 
device = deviceList.get("<deviceName>");

（很明顯，你會用的實際名稱替換<deviceName> 。設備

來源

2012-04-17 01:35:48 chandsie

+0

我用日誌知道mUsbManager的價值，我得到的價值是：[email protected]所以它不是null，我在模擬器上測試，因爲我沒有一個USB主機功能的設備：/所以字符串可以是任何不是問題的名稱？ – Andres 2012-04-17 01:50:31

+0

謝謝你:)你是對的。我正在測試仿真器，現在我把這個代碼用於測試USB設備：HashMap deviceList = mUsbManager.getDeviceList（）; Log.i（TAG，「Device List：」+ deviceList）;我在LogCat上打開「Device List：{}」，這意味着我沒有連接任何設備？ – Andres 2012-04-17 02:31:38

+1

是的，這是正確的。您需要將一些設備附加到您的模擬器。這裏有一個[問題]（http://stackoverflow.com/questions/1913979/how-to-emulate-usb-devices）關於如何做到這一點。 – chandsie 2012-04-17 02:50:52

3

minSdkVersion必須> = 12

要啓用USB主機API的支持，你應該添加一個名爲文件 android.hardware.usb.host.xml幷包含以下行：

<permissions> 
<feature name="android.hardware.usb.host"/>

來源

2013-12-19 08:04:43 dajun

+0

有關此https://github.com/452/USBHIDTerminal/wiki/How-to-enable-USB-host-API-support的更多詳細信息 – pantos27 2017-05-16 14:06:29

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