前面文章讲解了Android的蓝牙基本用法，本文讲得深入些，探讨下蓝牙方面的隐藏API。用过Android系统设置(Setting)的人都知道蓝牙搜索之后可以建立配对和解除配对，但是这两项功能的函数没有在SDK中给出，那么如何去使用这两项功能呢？本文利用JAVA的反射机制去调用这两项功能对应的函数：createBond和removeBond，具体的发掘和实现步骤如下：

1.使用Git工具下载platform/packages/apps/Settings.git，在Setting源码中查找关于建立配对和解除配对的API，知道这两个API的宿主(BluetoothDevice)；

2.使用反射机制对BluetoothDevice枚举其所有方法和常量，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(); }}

结果如下：

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.如果枚举发现API存在(SDK却隐藏)，则自己实现调用方法：

/** * 与设备配对 参考源码：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();}/** * 与设备解除配对 参考源码：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();}

此处注意:SDK之所以不给出隐藏的API肯定有其原因，也许是出于安全性或者是后续版本兼容性的考虑，因此不能保证隐藏API能在所有Android平台上很好地运行。

本文程序运行效果如下图所示：

main.xml源码如下：

<?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>

工具类ClsUtils.java源码如下：

package com.testReflect;import java.lang.reflect.Field;import java.lang.reflect.Method;import android.bluetooth.BluetoothDevice;import android.util.Log;public class ClsUtils { /** * 与设备配对 参考源码：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(); } /** * 与设备解除配对 参考源码：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的源码如下：

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();// 初始化本机蓝牙功能 if (btAdapt.getState() == BluetoothAdapter.STATE_OFF)// 开蓝牙  btAdapt.enable(); // 注册Receiver来获取蓝牙设备相关的结果 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();  // 显示所有收到的消息及其细节  for (int i = 0; i < lstName.length; i++) {  String keyName = lstName[i].toString();  Log.e(keyName, String.valueOf(b.get(keyName)));  }  // 搜索设备时，取得设备的MAC地址  if (BluetoothDevice.ACTION_FOUND.equals(action)) {  BluetoothDevice device = intent   .getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);  if (device.getBondState() == BluetoothDevice.BOND_NONE) {   String str = "未配对|" + device.getName() + "|" + device.getAddress();   lstDevices.add(str); // 获取设备名称和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("未配对"))  {    Toast.makeText(testReflect.this, "由未配对转为已配对", 500).show();   ClsUtils.createBond(btDevice.getClass(), btDevice);  }  else if(values[0].equals("已配对"))  {   Toast.makeText(testReflect.this, "由已配对转为未配对", 500).show();   ClsUtils.removeBond(btDevice.getClass(), btDevice);  }  } catch (Exception e) {  // TODO Auto-generated catch block  e.printStackTrace();  } } } /** * 按键处理 * @author GV * */ class ClickEvent implements View.OnClickListener { @Override public void onClick(View v) {  if (v == btnSearch) {//搜索附近的蓝牙设备  lstDevices.clear();  Object[] lstDevice = btAdapt.getBondedDevices().toArray();  for (int i = 0; i < lstDevice.length; i++) {   BluetoothDevice device=(BluetoothDevice)lstDevice[i];   String str = "已配对|" + device.getName() + "|" + device.getAddress();   lstDevices.add(str); // 获取设备名称和mac地址   adtDevices.notifyDataSetChanged();  }  // 开始搜索  setTitle("本机蓝牙地址：" + btAdapt.getAddress());  btAdapt.startDiscovery();  }  else if(v==btnShow){//显示BluetoothDevice的所有方法和常量，包括隐藏API  ClsUtils.printAllInform(btDevice.getClass());  } } }}

希望本文实例能够对大家进行Android程序开发有一定的借鉴帮助作用。