android realizes flashlight function through led

This article example for everyone to share android through led to achieve flashlight function of the specific code, for your reference, the specific content is as follows

Step 1 Add permissions:

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.FLASHLIGHT" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.flash" />

Step 2 implements the flashlight tool class:

import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.os.AsyncTask;

/**
 *Caution: On some devices, this method may take a long time to complete. It is best 
 *to call this method from a worker thread (possibly using android.os.AsyncTask) to 
 *avoid blocking the main application UI thread.
 */

public class FlashlightUtil extends AsyncTask<String, String, String> {

 private Camera camera;
 private int cameraId = 0; //  This function is not practical at present, so it will not be implemented here   ,   But it cannot be deleted 
 private Parameters parameters;
 public boolean isTorch = false;
 private boolean canFinish = false;
 private static FlashlightUtil flashlightUtil;

 private FlashlightUtil() {

 }

 /**
  *  Set the flashlight switch, turn on or off the flashlight, and set the opposite state according to the state of the flashlight  void 2016 Year 1 Month 12 Day 
  */
 public static void setSwitch() {
  if (null == flashlightUtil) {
   flashlightUtil = new FlashlightUtil();
   flashlightUtil.execute("");
  }
  flashlightUtil.setONOFF();
 }

 @Override
 protected String doInBackground(String... params) {
  // TODO Auto-generated method stub

  while (!canFinish) {
   if (null == camera) {
    camera = Camera.open(cameraId);
   }
   parameters = camera.getParameters();
   if (isTorch) {
    if (parameters.getFlashMode().equals(Parameters.FLASH_MODE_OFF)) {
     //  Turn on the spotlight 
     parameters.setFlashMode(Parameters.FLASH_MODE_TORCH);
     camera.setParameters(parameters);
     camera.startPreview();
    }
   } else {
    if (parameters.getFlashMode().equals(
      Parameters.FLASH_MODE_TORCH)) {
     //  Turn off the spotlight 
     camera.stopPreview(); //  Turn off the lights 
     camera.release(); //  Turn off the camera 
     camera = null;
    }
   }
  }

  return null;
 }

 /**
  *  This feature is temporarily turned off 
  * @hide
  */
 public FlashlightUtil setCameraId(int cameraId) {
  this.cameraId = cameraId;
  return flashlightUtil;
 }

 /**
  *  Turn on and off the flashlight, default 1 The second is open  2016 Year 1 Month 12 Day 
  */
 private void setONOFF() {
  isTorch = !isTorch;
 }


}

Step 3 Add the trigger event of the flashlight button (this is implemented in the layout file through onclick)

/**
 *  Turn on a flashlight 
 */
public void openFlashlight(View view) {
 FlashlightUtil.setSwitch() ;
}

The flashlight function is relatively simple, and it is opened and closed in one step.