嘗試獲取文件的URI時獲取空指針異常

Question

當活動打開時，會打開一個對話窗口，要求用戶從相機拍攝照片或從相冊中選取一張照片。只要我點擊按鈕打開相機，應用程序崩潰，我得到一個空指針異常與獲取URI相關。我一直在關注Google的演練，以便從相機中保存照片，並且似乎無法找到問題所在。

線發生錯誤：

Uri photoURI = FileProvider.getUriForFile(CreatePostActivity.this, 
           "xyz.beerme.beerme.provider", 
           photoFile); 

所有方法：

cameraButton.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); 
       if(intent.resolveActivity(getPackageManager()) != null){ 
        File photoFile = null; 
        try{ 
         photoFile = createImageFile(); 
        } catch (IOException ex){ 
         Snackbar message = Snackbar.make(findViewById(R.id.activity_create_post), "Error creating image", Snackbar.LENGTH_LONG); 
         message.show(); 
        } 
        if(photoFile != null){ 
         Uri photoURI = FileProvider.getUriForFile(CreatePostActivity.this, 
           "xyz.beerme.beerme.provider", 
           photoFile); 
         intent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI); 
         startActivityForResult(intent, REQUEST_CAMERA); 
        } 
       } 
       dialog.dismiss(); 
      } 
     }); 

createImageFile方法：

private File createImageFile() throws IOException{ 
     String timeStamp = new SimpleDateFormat("yyyMMdd_HHmmss").format(new Date()); 
     String imageFileName = "JPEG_" + timeStamp + "_beerme"; 
     File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES); 
     File image = File.createTempFile(
       imageFileName, 
       ".jpg", 
       storageDir 
     ); 

     mCurrentPhotoPath = image.getAbsolutePath(); 
     return image; 
    } 

清單：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    package="xyz.beerme.beerme"> 

    <!-- To auto-complete the email text field in the login form with the user's emails --> 
    <uses-permission android:name="android.permission.GET_ACCOUNTS" /> 
    <uses-permission android:name="android.permission.READ_PROFILE" /> 
    <uses-permission android:name="android.permission.READ_CONTACTS" /> 
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> 

    <application 
     android:allowBackup="true" 
     android:icon="@mipmap/ic_launcher" 
     android:label="@string/app_name" 
     android:supportsRtl="true" 
     android:theme="@style/AppTheme" 
     tools:replace="android:supportsRtl"> 
     <meta-data 
      android:name="com.google.android.geo.API_KEY" 
      android:value="redacted" /> 
     <provider 
      android:name="android.support.v4.content.FileProvider" 
      android:authorities="xyz.beerme.beerme.fileprovider" 
      android:exported="false" 
      android:grantUriPermissions="true"> 
      <meta-data 
       android:name="android.support.FILE_PROVIDER_PATHS" 
       android:resource="@xml/file_paths" ></meta-data> 
     </provider> 
     <activity android:name=".PostsActivity"> 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 
      <category android:name="android.intent.categroy.LAUNCHER"/> 
      </intent-filter> 
     </activity> 
     <activity android:name=".CreatePostActivity"></activity> 
    </application> 

</manifest> 

file_paths.xml

<?xml version="1.0" encoding="utf-8"?> 
<paths xmlns:android="http://schemas.android.com/apk/res/android"> 
    <external-path name="my_images" path="Android/data/xyz.beerme.beerme/files/Pictures" /> 
</paths> 

Answer 1

如果任何人發現這在未來，我輸入 「提供者」，而不是 「fileprovider」。由於提供者不存在，這是異常的來源。

Answer 2

試試下面的代碼createImageFile方法

private File createImageFile() { 
    File storageDir = context.getExternalFilesDir(Environment.DIRECTORY_PICTURES); 
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date()); 
    // path = path + (timeStamp + "1jpg"); 

    try { 
     file = File.createTempFile(timeStamp, ".jpg", storageDir); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 

    if (Build.VERSION.SDK_INT >= 24) 
     mCurrentPhotoPath = String.valueOf(FileProvider.getUriForFile(MainActivity.this, 
       BuildConfig.APPLICATION_ID + ".provider", file)); 
    else 
    mCurrentPhotoPath = String.valueOf(Uri.fromFile(file)); 
    return file; 
}