我的flash演示应用程序中的代码有点问题，目前我已经在三星手机上尝试过该应用程序并打开或关闭它。 但手电筒仅在手机屏幕仍然亮起时才开启，反之亦然，当手机屏幕熄灭时，手电筒应用程序也会关闭。虽然手电筒应用仍在使用。
这是我的整个代码
文件清单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.demo.flashlight">
<!-- Include required permissions for Google Mobile Ads to run. -->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".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> <!-- Include the AdActivity configChanges and theme. -->
</application>
</manifest>
文件Activity_main
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/background_dark"
tools:context="com.demo.flashlight.MainActivity">
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
ads:srcCompat="@drawable/on"
android:id="@+id/imageButton"
android:background="@android:color/background_dark"
android:clickable="false"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="145dp" />
</RelativeLayout>
文件MainActivity
package com.demo.flashlight;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageButton;
public class MainActivity extends AppCompatActivity {
private ImageButton imageButton;
private Camera camera;
private boolean isFlashOn;
private boolean hasFlash;
private Camera.Parameters params;
private MediaPlayer mp;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageButton = (ImageButton) findViewById(R.id.imageButton);
/*
* First check if device is supporting flashlight or not
*/
hasFlash = getApplicationContext().getPackageManager()
.hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
Context context = this;
PackageManager pm = context.getPackageManager();
// if device support camera?
if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
Log.e("err", "Device has no camera!");
return;
}
// get the camera
getCamera();
// displaying button image
toggleButtonImage();
/*
* Switch button click event to toggle flash on/off
*/
imageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (isFlashOn) {
// turn off flash
turnOffFlash();
} else {
// turn on flash
turnOnFlash();
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/*
// * 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;
}
params = camera.getParameters();
params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
camera.setParameters(params);
camera.startPreview();
isFlashOn = true;
toggleButtonImage();
}
}
/*
* Turning Off flash
*/
private void turnOffFlash() {
if (isFlashOn) {
if (camera == null || params == null) {
return;
}
params = camera.getParameters();
params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
camera.setParameters(params);
camera.stopPreview();
isFlashOn = false;
toggleButtonImage();
}
}
/*
* Toggle switch button images changing image states to on / off
*/
private void toggleButtonImage() {
if (isFlashOn) {
imageButton.setImageResource(R.drawable.on);
} else {
imageButton.setImageResource(R.drawable.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;
}
}
}
我不知道如何修复它。你能修理或指导我吗？ 谢谢
答案 0 :(得分：0)
当屏幕关闭时，活动会调用onPause和onStop。
尝试删除onPause中的turnOffFlash();。
如果不起作用，请尝试查看您的onStop。
祝你好运