Android가 플래시를 켜서 손전등을 만드는 상세한 설명

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))   // 
  {
  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;  

    /** 
     *   
     * @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" />