Question

大家好，我为Android开发了这款手电筒应用程序。程序首先检查设备是否支持手电筒;如果不是，它将通知错误消息。我已经在nexus 4（android 4.4）上启动它并且它正常工作但在我的galaxy nexus（android 4.3）手电筒没有打开并且没有显示错误消息

这是代码：

package com.androidhive.flashlight;

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;
        }
    }

}

这是androidmanifest.xml：

<?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>

有人可以告诉我为什么它不适用于星系连接？感谢

Answer 1

首先添加以下权限：

<!-- Allows access to the flashlight -->
<permission android:name="android.permission.FLASHLIGHT"
         android:permissionGroup="android.permission-group.HARDWARE_CONTROLS"
         android:protectionLevel="normal"
         android:label="@string/permlab_flashlight"
         android:description="@string/permdesc_flashlight" />

对于galaxy nexu，您需要使用大小为1dpx1dp的SurfaceView来打开手电筒。你还需要实现SurfaceHolder.Callback。

查看this question。

Android手电筒在Galaxy nexus上崩溃

1 个答案: