利用Java反射机制控制Nfc开关

利用Java反射机制控制Nfc开关

Nfc状态广播说明

/**
* Used as an int extra field in {@link #ACTION_ADAPTER_STATE_CHANGED}
* intents to request the current power state. Possible values are:
* {@link #STATE_OFF},
* {@link #STATE_TURNING_ON},
* {@link #STATE_ON},
* {@link #STATE_TURNING_OFF},
*/
public static final String EXTRA_ADAPTER_STATE = "android.nfc.extra.ADAPTER_STATE";

public static final int STATE_OFF = 1;
public static final int STATE_TURNING_ON = 2;
public static final int STATE_ON = 3;
public static final int STATE_TURNING_OFF = 4;

/**
* Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
* <p>
* Setting this flag enables polling for Nfc-A technology.
*/

Nfc状态广播action为“android.nfc.action.ADAPTER_STATE_CHANGED”,在这里他会传递四种int类型的状态值，其中STATE_OFF为关闭完成状态，STATE_ON为准备就绪状态，STATE_TURNING_ON为启动Nfc，STATE_TURNING_OFF为准备关闭状态。

编写BroadcastReceiver来接收Nfc状态

mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
Log.d(TAG, "接收成功");
String action = intent.getAction();
if (NfcAdapter.ACTION_ADAPTER_STATE_CHANGED.equals(action)) {
getStatus(intent.getIntExtra(NfcAdapter.EXTRA_ADAPTER_STATE, NfcAdapter.STATE_OFF));
}
}

private void getStatus(int intExtra) {
switch (intExtra) {
case NfcAdapter.STATE_OFF:
Message msg_off = new Message();
msg_off.obj = "close";
mHandler.sendMessage(msg_off);
break;
case NfcAdapter.STATE_ON:
Message msg_on = new Message();
msg_on.obj = "open";
mHandler.sendMessage(msg_on);
break;
case NfcAdapter.STATE_TURNING_OFF:
Message msg_turning_off = new Message();
msg_turning_off.obj = "turning off";
mHandler.sendMessage(msg_turning_off);
break;
case NfcAdapter.STATE_TURNING_ON:
Message msg_turning_on = new Message();
msg_turning_on.obj = "turning on";
mHandler.sendMessage(msg_turning_on);
break;
}
String a = intExtra + "";
Log.d(TAG, a);
}
};
IntentFilter intentFilter = new IntentFilter("android.nfc.action.ADAPTER_STATE_CHANGED");
registerReceiver(mReceiver, intentFilter);

接收成功后，通知handler来更新ui界面，把Nfc状态显示出来。

利用Java反射机制控制Nfc开关

控制Nfc开关的方法是android.nfc.NfcAdapter里面的enable()和disable()；在Android API中代码如下：

/**
* Enable NFC hardware.
*
* <p>This call is asynchronous. Listen for
* {@link #ACTION_ADAPTER_STATE_CHANGED} broadcasts to find out when the
* operation is complete.
*
* <p>If this returns true, then either NFC is already on, or
* a {@link #ACTION_ADAPTER_STATE_CHANGED} broadcast will be sent
* to indicate a state transition. If this returns false, then
* there is some problem that prevents an attempt to turn
* NFC on (for example we are in airplane mode and NFC is not
* toggleable in airplane mode on this platform).
*
* @hide
*/
@SystemApi
public boolean enable() {
try {
return sService.enable();
} catch (RemoteException e) {
attemptDeadServiceRecovery(e);
return false;
}
}

/**
* Disable NFC hardware.
*
* <p>No NFC features will work after this call, and the hardware
* will not perform or respond to any NFC communication.
*
* <p>This call is asynchronous. Listen for
* {@link #ACTION_ADAPTER_STATE_CHANGED} broadcasts to find out when the
* operation is complete.
*
* <p>If this returns true, then either NFC is already off, or
* a {@link #ACTION_ADAPTER_STATE_CHANGED} broadcast will be sent
* to indicate a state transition. If this r
4000
eturns false, then
* there is some problem that prevents an attempt to turn
* NFC off.
*
* @hide
*/
@SystemApi
public boolean disable() {
try {
return sService.disable(true);
} catch (RemoteException e) {
attemptDeadServiceRecovery(e);
return false;
}
}

因为在方法注释上面有@hide，说明这两个方法是API隐藏起来的，如果想要调用这两个方法控制Nfc开关就要用到Java反射，代码如下：

private void nfcEnable() {
try {
Class clazz = Class.forName("android.nfc.NfcAdapter");
Method enable = clazz.getMethod("enable");
// enable.setAccessible(true);
enable.invoke(adapter);

Log.d(TAG, "调用enable方法成功");
} catch (Exception e) {
e.printStackTrace();
}
}
private void nfcDisable() {
try {
Class clazz = Class.forName("android.nfc.NfcAdapter");
Method enable = clazz.getMethod("disable", boolean.class);
// enable.setAccessible(true);
enable.invoke(adapter, false);

Log.d(TAG, "调用disable方法成功");
} catch (Exception e) {
e.printStackTrace();
}
}

在支持Nfc的手机上调用这两个方法，可以观察手机Nfc设置中的Nfc开关，会随之而改变，需求实现！