我正在开发一个Android应用程序。该应用具有读取QR码的功能(这是迄今为止唯一实现的功能)。 我正在Android Studio上开发应用程序。 将应用程序安装到我的android手机后,系统显示权限被拒绝。 (已为该应用程序实现了请求权限,“权限被拒绝”是在权限被拒绝的情况下我放入android应用程序中的自定义消息。)
我可以在手机上手动授予该应用程序的权限。当我这样做时,它说授予了权限,并且有一秒钟可以访问摄像机,但是随后开始反复出现“ Permission Denied”消息,并且摄像机供稿丢失了。
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.folio" >
<uses-permission android:name="android.permission.CAMERA"/>
<uses-feature android:name="android.hardware.camera"/>
<uses-feature android:name="android.hardware.camera.autofocus"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme" >
<activity android:name=".MainActivity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
MainActivity.java
package com.example.folio;
import android.Manifest;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.net.Uri;
import android.os.Build;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;
import com.google.zxing.Result;
import me.dm7.barcodescanner.zxing.ZXingScannerView;
//import sun.applet.Main;
public class MainActivity extends AppCompatActivity implements ZXingScannerView.ResultHandler {
private static final int REQUEST_CAMERA=1;
private ZXingScannerView scannerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
scannerView=new ZXingScannerView(this);
setContentView(scannerView);
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
{
if(checkPermission())
{
Toast.makeText(MainActivity.this, "Permission granted!", Toast.LENGTH_LONG).show();
}
else
{
requestPermission();
}
}
}
private boolean checkPermission()
{
return (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA)== PackageManager.PERMISSION_GRANTED);
}
private void requestPermission()
{
ActivityCompat.requestPermissions(this, new String[]{CAMERA_SERVICE}, REQUEST_CAMERA);
}
public void onRequestPermissionsResult(int requestCode, String permission[], int grantResults[])
{
switch(requestCode)
{
case REQUEST_CAMERA:
if(grantResults.length>0)
{
boolean cameraAccepted = grantResults[0] == PackageManager.PERMISSION_GRANTED;
if(cameraAccepted)
{
Toast.makeText(MainActivity.this, "Permission Granted!", Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(MainActivity.this, "Permission Denied!", Toast.LENGTH_LONG).show();
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
{
if(shouldShowRequestPermissionRationale(CAMERA_SERVICE))
{
displayAlertMessage("Please allow access!", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
requestPermissions(new String[]{CAMERA_SERVICE}, REQUEST_CAMERA);
}
});
return;
}
}
}
}
break;
}
}
@Override
public void onResume()
{
super.onResume();
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
{
if(checkPermission())
{
if(scannerView==null)
{
scannerView=new ZXingScannerView(this);
setContentView(scannerView);
}
scannerView.setResultHandler(this);
scannerView.startCamera();
}
{
requestPermission();
}
}
}
@Override
public void onDestroy()
{
super.onDestroy();
scannerView.stopCamera();
}
public void displayAlertMessage(String message, DialogInterface.OnClickListener listener)
{
new AlertDialog.Builder(MainActivity.this)
.setMessage(message)
.setPositiveButton("Ok", listener)
.setNegativeButton("Cancel", null)
.create()
.show();
}
@Override
public void handleResult(Result result) {
final String scanResult=result.getText();
AlertDialog.Builder builder=new AlertDialog.Builder(this);
builder.setTitle("Scan result");
builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
scannerView.resumeCameraPreview(MainActivity.this);
}
});
builder.setNeutralButton("Visit", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(scanResult));
startActivity(intent);
}
});
builder.setMessage(scanResult);
AlertDialog alert=builder.create();
alert.show();
}
}
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答案 0 :(得分:5)
ActivityCompat.requestPermissions(this, new String[]{CAMERA_SERVICE}, REQUEST_CAMERA);
不清楚CAMERA_SERVICE
是什么。但是,这应该是一组权限,因此很可能您应该在此处使用Manifest.permission.CAMERA
:
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA);
答案 1 :(得分:1)
您的onResume()方法再次调用requestPermission(),我认为您应该将其置于其他条件下,而不是直接调用它。