在写手电筒APP之前，当然已经参考market上的很多手电筒APP，还有网上如何实现手电筒功能的各种源码。不管是源码还是market上的APP，总结了几点的问题。
1.我下载market上的所有手电筒APP都是通过Camera打开闪光灯的方式来实现的，但是大部分APP在打开Camera时没有进行异常处理工作，也没有任何的提示，如果当其他的程序在使用Camera时，并且返回或点Home后没有释放Camera，这时在启动相应的手电筒APP就会出现崩溃或者手电筒功能已经失效，这种用户体验用户是不能接受的！
2,网上很多Camera打开闪光灯实现手电筒的源码，而且原理都是一样的，当然这些代码并没有错误，但存在的问题是这些源码在有的手机版本上能够实现相应的功能，在另外的手机版本上就不起作用了，在CSDN资源中的大部分手电筒Demo也都会存在此问题，兼容性不好！
我自己实现的这个手电筒很简单，没有任何的UI界面，进入APP后就直接照明，实现的原理就2点：
1.跟其他手电筒APP一样，用Camera打开闪光灯开始照明
2.将当前屏幕的背光调节为最亮状态，退出时在恢复之前的背光值
代码和布局如下：
MainActivity.java
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
}
}
activity_main.xmlactivity_main.xml
<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>
好了，有兴趣的朋友可以下载源码，代码中都已加入了详细的注释
如果下载后调试发现运行不正常，可以反馈一起交流
