Android 开启闪光灯做手电筒的详解

public class HandLightActivity extends Activity implements OnClickListener{
private ToggleButton toggleButton;
private Camera m_Camera;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.handlight);
toggleButton = (ToggleButton)this.findViewById(R.id.toggleButton1);
toggleButton.setOnClickListener(this);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}
@Override
public void onClick(View v) {
ToggleButton tb = (ToggleButton)v;
if(!tb.isChecked()){
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
  {
  if ( null == m_Camera ) 
    { 
        m_Camera = Camera.open();     
    } 

    Camera.Parameters parameters = m_Camera.getParameters();              
    parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);   
    m_Camera.setParameters( parameters );             
    m_Camera.startPreview();
toggleButton.setBackgroundColor(0x30ffffff);
  }
}
}else{
if ( m_Camera != null ) 
   { 
       m_Camera.stopPreview(); 
       m_Camera.release(); 
       m_Camera = null; 
   }
toggleButton.setBackgroundColor(0xffffffff);
}
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ToggleButton android:id="@+id/toggleButton1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:checked="true"
        android:text="ToggleButton"/>
</LinearLayout>

package android.os; 

/** {@hide} */ 
interface IHardwareService 
{ 
    // obsolete flashlight support  
    boolean getFlashlightEnabled(); 
    void setFlashlightEnabled(boolean on); 
}

import android.os.IHardwareService; 

    /**
     * 设置闪光灯的开启和关闭
     * @param isEnable
     * @author linc
     * @date 2012-3-18
     */ 
    private void setFlashlightEnabled(boolean isEnable) 
    { 
        try 
        { 
            Method method = Class.forName("android.os.ServiceManager").getMethod("getService", String.class); 
            IBinder binder = (IBinder) method.invoke(null, new Object[] { "hardware" }); 

            IHardwareService localhardwareservice = IHardwareService.Stub.asInterface(binder); 
            localhardwareservice.setFlashlightEnabled(isEnable); 
        } 
        catch (Exception e) 
        { 
            e.printStackTrace(); 
        } 

    } 

<uses-permission android:name="android.permission.FLASHLIGHT" /> 
    <uses-permission android:name="android.permission.HARDWARE_TEST" />