Android手电筒兼容各个手机与版本

package huahua.flashlight;
 
import java.io.IOException;
 
import android.app.Activity;
import android.content.ContentResolver;
import android.content.pm.FeatureInfo;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.os.Bundle;
import android.provider.Settings;
import android.provider.Settings.SettingNotFoundException;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Toast;
 
/**
 * 花花手电筒
 * @author huahua
 */
public class MainActivity extends Activity implements SurfaceHolder.Callback{
 private static final String TAG = "huahua"; 
 /**
 * 进入APP时的背光亮度值
 */
 int normal;
 /**
 * 进入APP时，是否为自动调节亮度状态
 */
 boolean AutoBrightnessOpen = false;
 
 private Camera camera; 
 
 private SurfaceView surfaceView; 
 private SurfaceHolder surfaceHolder; 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 
 //去除title 
 this.requestWindowFeature(Window.FEATURE_NO_TITLE); 
  
 //去掉Activity上面的状态栏 
 getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
 WindowManager.LayoutParams.FLAG_FULLSCREEN); 
 
 setContentView(R.layout.activity_main);
 
 surfaceView = (SurfaceView) this.findViewById(R.id.surfaceview); 
 surfaceHolder = surfaceView.getHolder(); 
 surfaceHolder.addCallback(this); 
 surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
 
 if(isAutoBrightness(getContentResolver()))
 {
 AutoBrightnessOpen = true;
 }
 
 normal = Settings.System.getInt(getContentResolver(), 
  Settings.System.SCREEN_BRIGHTNESS, 255); 
 
 PackageManager pm= this.getPackageManager();
 FeatureInfo[] features=pm.getSystemAvailableFeatures();
 for(FeatureInfo f : features)
 {
 if(PackageManager.FEATURE_CAMERA_FLASH.equals(f.name)) //判断设备是否支持闪光灯
 {
 Log.d("huahua","支持闪光灯");
 }
 }
 
 }
 @Override
 protected void onPause() {
 // TODO Auto-generated method stub
 super.onPause();
 
 Closeshoudian();
 }
 
 @Override
 protected void onResume() {
 // TODO Auto-generated method stub
 super.onResume();
 
 Openshoudian();
 }
 
 /**
 * 判断是否开启了自动亮度调节
 * 
 * @param aContext
 * @return
 */
 public boolean isAutoBrightness(ContentResolver aContentResolver) {
 boolean automicBrightness = false;
 try {
  automicBrightness = Settings.System.getInt(aContentResolver,
   Settings.System.SCREEN_BRIGHTNESS_MODE) == Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC;
 } catch (SettingNotFoundException e) {
  e.printStackTrace();
 }
 return automicBrightness;
 }
 
 /**
 * 停止自动亮度调节
 * 
 * @param activity
 */
 public void stopAutoBrightness(Activity activity) {
 Settings.System.putInt(activity.getContentResolver(),
  Settings.System.SCREEN_BRIGHTNESS_MODE,
  Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
 }
 
 /**
 * 恢复自动亮度调节
 * 
 * @param activity
 */
 public void setAutoBrightness(Activity activity) {
 Settings.System.putInt(activity.getContentResolver(),
  Settings.System.SCREEN_BRIGHTNESS_MODE,
  Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC);
 }
 
 /**
 * 打开手电筒
 */
 public void Openshoudian()
 {
 //异常处理一定要加，否则Camera打开失败的话程序会崩溃
 try {
  Log.d("huahua","camera打开");
 camera = Camera.open(); 
 } catch (Exception e) {
 Log.d("huahua","Camera打开有问题");
 Toast.makeText(MainActivity.this, "Camera被占用，请先关闭", Toast.LENGTH_SHORT).show();
 }
 
 if(camera != null)
 {
 //打开闪光灯
 camera.startPreview(); 
 Camera.Parameters parameter = camera.getParameters(); 
 parameter.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH); 
 camera.setParameters(parameter);
 Log.d("huahua","闪光灯打开");
 
 //先关闭自动调节背光功能，才可以调节背光
 if(AutoBrightnessOpen)
 {
 stopAutoBrightness(MainActivity.this);
 }
 
 //将背光设置为最亮
  WindowManager.LayoutParams lp = getWindow().getAttributes();
  lp.screenBrightness = Float.valueOf(255) * (1f / 255f);
  getWindow().setAttributes(lp);
 }
 }
 
 /**
 * 关闭手电筒
 */
 public void Closeshoudian()
 {
 if (camera != null)
 {
  //关闭闪光灯
  Log.d("huahua", "closeCamera()");
 camera.getParameters().setFlashMode(Camera.Parameters.FLASH_MODE_OFF); 
 camera.setParameters(camera.getParameters());
  camera.stopPreview();
  camera.release();
  camera = null;
  
  //恢复进入程序前的背光值
  WindowManager.LayoutParams lp = getWindow().getAttributes();
  lp.screenBrightness = Float.valueOf(normal) * (1f / 255f);
  getWindow().setAttributes(lp);
  
  //如果进入APP时背光为自动调节，则退出时需要恢复为自动调节状态
 if(AutoBrightnessOpen)
 {
 setAutoBrightness(MainActivity.this);
 }
 }
 }
 
 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width,
 int height) {
 // TODO Auto-generated method stub
 
 }
 @Override
 public void surfaceCreated(SurfaceHolder holder) {
 try { 
 if(camera != null)
 {
 camera.setPreviewDisplay(holder); 
 }
 } catch (IOException e) { 
 e.printStackTrace(); 
 } 
 
 }
 
 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
 // TODO Auto-generated method stub
 
 }
 
 
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context=".MainActivity" >
 
 <SurfaceView
 android:id="@ id/surfaceview"
 android:layout_width="match_parent"
 android:layout_height="match_parent" 
 android:background="#FFFFFF"/>
 
</LinearLayout>