Question

我是一名Android开发者，我想在我的移动手电筒上。我有Nexus5。我的代码如下。任何人都可以帮助我吗？告诉我这里缺少什么？我已经设置了权限，没有错误发生但是app没有正常工作。

主要Activity.Java

 import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.DialogInterface;
 import android.content.pm.PackageManager;
 import android.hardware.Camera;
 import android.hardware.Camera.Parameters;
 import android.media.MediaPlayer;
 import android.media.MediaPlayer.OnCompletionListener;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.widget.ImageButton;

public class MainActivity extends Activity {

ImageButton btnSwitch;

private Camera camera;
private boolean isFlashOn;
private boolean hasFlash;
Parameters params;
MediaPlayer mp;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // flash switch button
    btnSwitch = (ImageButton) findViewById(R.id.btnSwitch);

    /*
     * First check if device is supporting flashlight or not
     */
    hasFlash = getApplicationContext().getPackageManager()
            .hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);

    if (!hasFlash) {
        // device doesn't support flash
        // Show alert message and close the application
        AlertDialog alert = new AlertDialog.Builder(MainActivity.this)
                .create();
        alert.setTitle("Error");
        alert.setMessage("Sorry, your device doesn't support flash light!");
        alert.setButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                // closing the application
                finish();
            }
        });
        alert.show();
        return;
    }

    // get the camera
    getCamera();

    // displaying button image
    toggleButtonImage();

    /*
     * Switch button click event to toggle flash on/off
     */
    btnSwitch.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            if (isFlashOn) {
                // turn off flash
                turnOffFlash();
            } else {
                // turn on flash
                turnOnFlash();
            }
        }
    });
}

/*
 * Get the camera
 */
private void getCamera() {
    if (camera == null) {
        try {
            camera = Camera.open();
            params = camera.getParameters();
        } catch (RuntimeException e) {
            Log.e("Camera Error. Failed to Open. Error: ", e.getMessage());
        }
    }
}

/*
 * Turning On flash
 */
private void turnOnFlash() {
    if (!isFlashOn) {
        if (camera == null || params == null) {
            return;
        }
        // play sound
        playSound();

        params = camera.getParameters();
        params.setFlashMode(Parameters.FLASH_MODE_TORCH);
        camera.setParameters(params);
        camera.startPreview();
        isFlashOn = true;

        // changing button/switch image
        toggleButtonImage();
    }

}

/*
 * Turning Off flash
 */
private void turnOffFlash() {
    if (isFlashOn) {
        if (camera == null || params == null) {
            return;
        }
        // play sound
        playSound();

        params = camera.getParameters();
        params.setFlashMode(Parameters.FLASH_MODE_OFF);
        camera.setParameters(params);
        camera.stopPreview();
        isFlashOn = false;

        // changing button/switch image
        toggleButtonImage();
    }
}

/*
 * Playing sound
 * will play button toggle sound on flash on / off
 * */
private void playSound(){
    if(isFlashOn){
        mp = MediaPlayer.create(MainActivity.this, R.raw.light_switch_off);
    }else{
        mp = MediaPlayer.create(MainActivity.this, R.raw.light_switch_on);
    }
    mp.setOnCompletionListener(new OnCompletionListener() {

        @Override
        public void onCompletion(MediaPlayer mp) {
            // TODO Auto-generated method stub
            mp.release();
        }
    }); 
    mp.start();
}

/*
 * Toggle switch button images
 * changing image states to on / off
 * */
private void toggleButtonImage(){
    if(isFlashOn){
        btnSwitch.setImageResource(R.drawable.btn_switch_on);
    }else{
        btnSwitch.setImageResource(R.drawable.btn_switch_off);
    }
}

@Override
protected void onDestroy() {
    super.onDestroy();
}

@Override
protected void onPause() {
    super.onPause();

    // on pause turn off the flash
    turnOffFlash();
}

@Override
protected void onRestart() {
    super.onRestart();
}

@Override
protected void onResume() {
    super.onResume();

    // on resume turn on the flash
    if(hasFlash)
        turnOnFlash();
}

@Override
protected void onStart() {
    super.onStart();

    // on starting the app get the camera params
    getCamera();
}

@Override
protected void onStop() {
    super.onStop();

    // on stop release the camera
    if (camera != null) {
        camera.release();
        camera = null;
    }
}

}

我的任何Android.manifest文件都在这里。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.androidhive.flashlight"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="17" />

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

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.androidhive.flashlight.MainActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

</manifest>

我发布第二次，我第一次没有得到解决方案。我读了很多教程。

Answer 1

这些是Manifest中的权限。我忘了告诉你，我的坏！

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

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

Answer 2

这可能不起作用的原因有很多。 hasFlash可能不是检查闪存的最佳方法。除了FLASH_MODE_ON之外，您可能还想检查FLASH_MODE_TORCH。您可能需要预览并实施SurfaceHolder.Callback。你可能会在android:targetSdkVersion="17"增加{{1}}。我刚建了一个开源手电筒。如果您想查看/使用源代码，它适用于Nexus 5。 Flashlight by Joe github

Answer 3

在访问闪光灯之前，您必须先打开相机。您声明了相机但没有使用它。试试这个。

public void cameraon() {
    cam = Camera.open();
    par = cam.getParameters();
    par.setFlashMode(Parameters.FLASH_MODE_ON);
    par.setFlashMode(Parameters.FLASH_MODE_TORCH);
    cam.setParameters(par);
    cam.startPreview();
}

public void cameraoff() {
    par.setFlashMode(Parameters.FLASH_MODE_OFF);
    cam.setParameters(par);
    cam.stopPreview();
    cam.release();
}

Answer 4

我知道它的晚期可能会帮助别人。您的代码不起作用的原因是您同时使用相机和媒体播放器。如果闪光灯亮起，您的媒体播放器将停止工作。或者，如果媒体播放器正在运行，那么您将无法获得点亮Flash所需的相机实例。

闪光灯不亮？

4 个答案: