Android提高之藍牙隱藏API探秘

前面文章講解了Android的藍牙基本用法，本文講得深入些，探討下藍牙方面的隱藏API。用過Android系統設置(Setting)的人都知道藍牙搜索之後可以建立配對和解除配對，但是這兩項功能的函數沒有在SDK中給出，那麼如何去使用這兩項功能呢？本文利用JAVA的反射機制去調用這兩項功能對應的函數：createBond和removeBond，具體的發掘和實現步驟如下：

1.使用Git工具下載platform/packages/apps/Settings.git，在Setting源碼中查找關於建立配對和解除配對的API，知道這兩個API的宿主(BluetoothDevice)；

2.使用反射機制對BluetoothDevice枚舉其所有方法和常量，看看是否存在:

static public void printAllInform(Class clsShow) {
 try {
 // 取得所有方法
 Method[] hideMethod = clsShow.getMethods();
 int i = 0;
 for (; i < hideMethod.length; i++) {
  Log.e("method name", hideMethod[i].getName());
 }
 // 取得所有常量
 Field[] allFields = clsShow.getFields();
 for (i = 0; i < allFields.length; i++) {
  Log.e("Field name", allFields[i].getName());
 }
 } catch (SecurityException e) {
 // throw new RuntimeException(e.getMessage());
 e.printStackTrace();
 } catch (IllegalArgumentException e) {
 // throw new RuntimeException(e.getMessage());
 e.printStackTrace();
 } catch (Exception e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
}

結果如下：

11-29 09:19:12.012: method name(452): cancelBondProcess
11-29 09:19:12.020: method name(452): cancelPairingUserInput
11-29 09:19:12.020: method name(452): createBond
11-29 09:19:12.020: method name(452): createInsecureRfcommSocket
11-29 09:19:12.027: method name(452): createRfcommSocket
11-29 09:19:12.027: method name(452): createRfcommSocketToServiceRecord
11-29 09:19:12.027: method name(452): createScoSocket
11-29 09:19:12.027: method name(452): describeContents
11-29 09:19:12.035: method name(452): equals
11-29 09:19:12.035: method name(452): fetchUuidsWithSdp
11-29 09:19:12.035: method name(452): getAddress
11-29 09:19:12.035: method name(452): getBluetoothClass
11-29 09:19:12.043: method name(452): getBondState
11-29 09:19:12.043: method name(452): getName
11-29 09:19:12.043: method name(452): getServiceChannel
11-29 09:19:12.043: method name(452): getTrustState
11-29 09:19:12.043: method name(452): getUuids
11-29 09:19:12.043: method name(452): hashCode
11-29 09:19:12.043: method name(452): isBluetoothDock
11-29 09:19:12.043: method name(452): removeBond
11-29 09:19:12.043: method name(452): setPairingConfirmation
11-29 09:19:12.043: method name(452): setPasskey
11-29 09:19:12.043: method name(452): setPin
11-29 09:19:12.043: method name(452): setTrust
11-29 09:19:12.043: method name(452): toString
11-29 09:19:12.043: method name(452): writeToParcel
11-29 09:19:12.043: method name(452): convertPinToBytes
11-29 09:19:12.043: method name(452): getClass
11-29 09:19:12.043: method name(452): notify
11-29 09:19:12.043: method name(452): notifyAll
11-29 09:19:12.043: method name(452): wait
11-29 09:19:12.051: method name(452): wait
11-29 09:19:12.051: method name(452): wait

3.如果枚舉發現API存在(SDK卻隱藏)，則自己實現調用方法：

/**
 * 與設備配對 參考源碼：platform/packages/apps/Settings.git
 * /Settings/src/com/android/settings/bluetooth/CachedBluetoothDevice.java
 */
static public boolean createBond(Class btClass,BluetoothDevice btDevice) throws Exception {
 Method createBondMethod = btClass.getMethod("createBond");
 Boolean returnValue = (Boolean) createBondMethod.invoke(btDevice);
 return returnValue.booleanValue();
}
/**
 * 與設備解除配對 參考源碼：platform/packages/apps/Settings.git
 * /Settings/src/com/android/settings/bluetooth/CachedBluetoothDevice.java
 */
static public boolean removeBond(Class btClass,BluetoothDevice btDevice) throws Exception {
 Method removeBondMethod = btClass.getMethod("removeBond");
 Boolean returnValue = (Boolean) removeBondMethod.invoke(btDevice);
 return returnValue.booleanValue();
}

此處注意:SDK之所以不給出隱藏的API肯定有其原因，也許是出於安全性或者是後續版本兼容性的考慮，因此不能保證隱藏API能在所有Android平台上很好地運行。

本文程序運行效果如下圖所示：

main.xml源碼如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 <LinearLayout android:id="@+id/LinearLayout01"
 android:layout_height="wrap_content" android:layout_width="fill_parent">
 <Button android:layout_height="wrap_content" android:id="@+id/btnSearch"
  android:text="Search" android:layout_width="160dip"></Button>
 <Button android:layout_height="wrap_content"
  android:layout_width="160dip" android:text="Show" android:id="@+id/btnShow"></Button>
 </LinearLayout>
 <LinearLayout android:id="@+id/LinearLayout02"
 android:layout_width="wrap_content" android:layout_height="wrap_content"></LinearLayout>
 <ListView android:id="@+id/ListView01" android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 </ListView>
</LinearLayout>

工具類ClsUtils.java源碼如下：

package com.testReflect;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import android.bluetooth.BluetoothDevice;
import android.util.Log;
public class ClsUtils {
 /**
 * 與設備配對 參考源碼：platform/packages/apps/Settings.git
 * /Settings/src/com/android/settings/bluetooth/CachedBluetoothDevice.java
 */
 static public boolean createBond(Class btClass,BluetoothDevice btDevice) throws Exception {
 Method createBondMethod = btClass.getMethod("createBond");
 Boolean returnValue = (Boolean) createBondMethod.invoke(btDevice);
 return returnValue.booleanValue();
 }
 /**
 * 與設備解除配對 參考源碼：platform/packages/apps/Settings.git
 * /Settings/src/com/android/settings/bluetooth/CachedBluetoothDevice.java
 */
 static public boolean removeBond(Class btClass,BluetoothDevice btDevice) throws Exception {
 Method removeBondMethod = btClass.getMethod("removeBond");
 Boolean returnValue = (Boolean) removeBondMethod.invoke(btDevice);
 return returnValue.booleanValue();
 }
 /**
 * 
 * @param clsShow
 */
 static public void printAllInform(Class clsShow) {
 try {
  // 取得所有方法
  Method[] hideMethod = clsShow.getMethods();
  int i = 0;
  for (; i < hideMethod.length; i++) {
  Log.e("method name", hideMethod[i].getName());
  }
  // 取得所有常量
  Field[] allFields = clsShow.getFields();
  for (i = 0; i < allFields.length; i++) {
  Log.e("Field name", allFields[i].getName());
  }
 } catch (SecurityException e) {
  // throw new RuntimeException(e.getMessage());
  e.printStackTrace();
 } catch (IllegalArgumentException e) {
  // throw new RuntimeException(e.getMessage());
  e.printStackTrace();
 } catch (Exception e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }
 }
}

主程序testReflect.java的源碼如下：

package com.testReflect;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
public class testReflect extends Activity {
 Button btnSearch, btnShow;
 ListView lvBTDevices;
 ArrayAdapter<String> adtDevices;
 List<String> lstDevices = new ArrayList<String>();
 BluetoothDevice btDevice;
 BluetoothAdapter btAdapt;
 @Override
 public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main);
 btnSearch = (Button) this.findViewById(R.id.btnSearch);
 btnSearch.setOnClickListener(new ClickEvent());
 btnShow = (Button) this.findViewById(R.id.btnShow);
 btnShow.setOnClickListener(new ClickEvent());
 lvBTDevices = (ListView) this.findViewById(R.id.ListView01);
 adtDevices = new ArrayAdapter<String>(testReflect.this,
  android.R.layout.simple_list_item_1, lstDevices);
 lvBTDevices.setAdapter(adtDevices);
 lvBTDevices.setOnItemClickListener(new ItemClickEvent());

 btAdapt = BluetoothAdapter.getDefaultAdapter();// 初始化本機藍牙功能
 if (btAdapt.getState() == BluetoothAdapter.STATE_OFF)// 開藍牙
  btAdapt.enable();
 // 注冊Receiver來獲取藍牙設備相關的結果
 IntentFilter intent = new IntentFilter();
 intent.addAction(BluetoothDevice.ACTION_FOUND);
 intent.addAction(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
 registerReceiver(searchDevices, intent);

 }
 private BroadcastReceiver searchDevices = new BroadcastReceiver() {
 public void onReceive(Context context, Intent intent) {
  String action = intent.getAction();
  Bundle b = intent.getExtras();
  Object[] lstName = b.keySet().toArray();
  // 顯示所有收到的消息及其細節
  for (int i = 0; i < lstName.length; i++) {
  String keyName = lstName[i].toString();
  Log.e(keyName, String.valueOf(b.get(keyName)));
  }
  // 搜索設備時，取得設備的MAC地址
  if (BluetoothDevice.ACTION_FOUND.equals(action)) {
  BluetoothDevice device = intent
   .getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
  if (device.getBondState() == BluetoothDevice.BOND_NONE) {
   String str = "未配對|" + device.getName() + "|" + device.getAddress();
   lstDevices.add(str); // 獲取設備名稱和mac地址
   adtDevices.notifyDataSetChanged();
  }
  }
 }
 };
 class ItemClickEvent implements AdapterView.OnItemClickListener {

 @Override
 public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
  long arg3) {
  btAdapt.cancelDiscovery();
  String str = lstDevices.get(arg2);
  String[] values = str.split("//|");
  String address=values[2];
  btDevice = btAdapt.getRemoteDevice(address);
  try {
  if(values[0].equals("未配對"))
  { 
   Toast.makeText(testReflect.this, "由未配對轉為已配對", 500).show();
   ClsUtils.createBond(btDevice.getClass(), btDevice);
  }
  else if(values[0].equals("已配對"))
  {
   Toast.makeText(testReflect.this, "由已配對轉為未配對", 500).show();
   ClsUtils.removeBond(btDevice.getClass(), btDevice);
  }
  } catch (Exception e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
  }
 }
 }
 /**
 * 按鍵處理
 * @author GV
 *
 */
 class ClickEvent implements View.OnClickListener {
 @Override
 public void onClick(View v) {
  if (v == btnSearch) {//搜索附近的藍牙設備
  lstDevices.clear();
  Object[] lstDevice = btAdapt.getBondedDevices().toArray();
  for (int i = 0; i < lstDevice.length; i++) {
   BluetoothDevice device=(BluetoothDevice)lstDevice[i];
   String str = "已配對|" + device.getName() + "|" + device.getAddress();
   lstDevices.add(str); // 獲取設備名稱和mac地址
   adtDevices.notifyDataSetChanged();
  }
  // 開始搜索
  setTitle("本機藍牙地址：" + btAdapt.getAddress());
  btAdapt.startDiscovery();
  }
  else if(v==btnShow){//顯示BluetoothDevice的所有方法和常量，包括隱藏API
  ClsUtils.printAllInform(btDevice.getClass());
  }
 }
 }
}

希望本文實例能夠對大家進行Android程序開發有一定的借鑒幫助作用。