我有一个Android应用程序，我从相机拍摄照片，然后我想将其转换为base64格式，但我接受拍摄的照片后出错。看起来我无法访问外部存储，我认为这会导致空位图。 ANDROID_MANIFEST中的许可已被宣布。如何解决权限问题以及可能导致空位图的原因？
这是我的代码：
public class MainActivity extends AppCompatActivity {
private Button takePhotoButton;
private String encoded_string, image_name;
private Bitmap bitmap;
private File file;
private Uri file_uri;
private String getRealPathFromURI(Uri contentUri) {
String[] proj = { MediaStore.Images.Media.DATA };
CursorLoader loader = new CursorLoader(this, contentUri, proj, null, null, null);
Cursor cursor = loader.loadInBackground();
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
String result = cursor.getString(column_index);
cursor.close();
return result;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
takePhotoButton = (Button) findViewById(R.id.take_photo);
takePhotoButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
getFileUri();
i.putExtra(MediaStore.EXTRA_OUTPUT, file_uri);
startActivityForResult(i, 10);
}
});
}
private void getFileUri() {
image_name= "test123.jpg";
file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES) + File.separator + image_name);
file_uri = Uri.fromFile(file);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(requestCode == 10 && resultCode == RESULT_OK){
new Encode_image().execute();
}
}
private class Encode_image extends AsyncTask<Void, Void, Void>{
@Override
protected Void doInBackground(Void... params) {
BitmapFactory.Options options = new BitmapFactory.Options();
int scale = 8;
options.inSampleSize = scale;
options.inJustDecodeBounds = false;
bitmap = BitmapFactory.decodeFile(file_uri.getPath(), options);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 50, stream);
//convert stream to byte array
byte[] array = stream.toByteArray();
encoded_string = Base64.encodeToString(array, 0);
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
makeRequest();
}
}
private void makeRequest() {
RequestQueue requestQueue = Volley.newRequestQueue(this);
StringRequest request = new StringRequest(Request.Method.POST, "http://192.168.1.102/AndroidFileUpload/connection.php",
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
HashMap<String, String> map = new HashMap<>();
map.put("encoded_string", encoded_string);
map.put("image_name", image_name);
return map;
}
};
requestQueue.add(request);
}
}
我在行
中收到错误bitmap.compress(Bitmap.CompressFormat.JPEG, 50, stream)
因为位图为空。
运行应用程序后崩溃返回了此错误/消息：
E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: /storage/emulated/0/Pictures/test123.jpg: open failed: EACCES (Permission denied)
E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
Process: com.example.andrei.sendphotos, PID: 17972
java.lang.RuntimeException: An error occurred while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:309)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference
at com.example.andrei.sendphotos.MainActivity$Encode_image.doInBackground(MainActivity.java:115)
at com.example.andrei.sendphotos.MainActivity$Encode_image.doInBackground(MainActivity.java:92)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
E/Surface: getSlotFromBufferLocked: unknown buffer: 0xa23ae0e0
Android Manifest xml：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.andrei.sendphotos">
<uses-permission android:name="android.permission.INTERNET" />
<uses-feature android:name="android.hardware.camera" android:required="true" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<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">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
答案 0 :(得分：0)
您需要为Android 6.X实现运行时权限。请参阅此处的官方文档：Requesting Runtime Permissions
我可以使用我自己的公共助手课程：PermissionHelper.java
或者您可以简单地将目标SDK版本降级为22以及所有依赖项，我不建议这样做。
Android 6.X的一个主要变化是强制执行运行时权限模型。谷歌必须保持市场上已有的应用程序的向后兼容性（不检查并询问运行时的权限）。
因此他们使其工作 - 如果应用程序针对SDK版本22，则所有权限将在安装时授予应用程序。但是，如果应用程序以SDK 23为目标，则默认情况下不会授予权限，而应用程序应在执行任何需要dangerous permissions的任务之前检查权限，并在继续执行任务之前询问用户是否已授予权限。