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后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，那么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源碼中查找關于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，也許是出于安全性或者是后續版本兼容性的考慮，因此不能保證隱藏API能在所有Android平臺上很好地運行。
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("http://|"); 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。
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