我想从内部存储中读取和保存图像/位图。
在我的布局中，我有一个按钮和一个图像视图。当我单击按钮时，我想选择画廊的图片来保存它。当我单击图像视图时，我希望显示保存的图像。
这就是我尝试过的：
布局：
<Button
android:id="@+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="80dp"
android:layout_marginRight="80dp"
android:text="Upload Image"
android:onClick="onClickUpload"
android:layout_marginBottom="30dp" />
<ImageView
android:id="@+id/imgPicker"
android:layout_width="200dp"
android:layout_height="200dp"
android:layout_marginTop="15dp"
android:layout_marginLeft="30dp"
android:layout_marginRight="30dp"
android:onClick="onClickShow"
app:srcCompat="@android:color/holo_orange_dark" />
请求许可的读取功能
public void onClickUpload(View view) {
// request permission to read external storage (explicit necessary since API Level 23)
// Here, thisActivity is the current activity
if (ContextCompat.checkSelfPermission(DetailActivity.this,
Manifest.permission.READ_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED) {
// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(DetailActivity.this,
Manifest.permission.READ_EXTERNAL_STORAGE)) {
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(DetailActivity.this,
new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
// MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
// app-defined int constant. The callback method gets the
// result of the request.
}
} else {
startActivityForResult(new Intent(Intent.ACTION_PICK,
android.provider.MediaStore.Images.Media.INTERNAL_CONTENT_URI), GET_FROM_GALLERY);
}
}
覆盖 onRquestPermissionResult
/*
find out whether the permission was granted
*/
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// start Activity if granted
startActivityForResult(new Intent(Intent.ACTION_PICK,
MediaStore.Images.Media.INTERNAL_CONTENT_URI), GET_FROM_GALLERY);
} else {
// permission denied, boo! Disable the
// functionality that depends on this permission.
}
return;
}
// other 'case' lines to check for other
// permissions this app might request
}
}
授予权限后运行：
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
//Detects request codes
if(requestCode==GET_FROM_GALLERY && resultCode == Activity.RESULT_OK) {
Uri selectedImage = data.getData();
Bitmap bitmap = null;
try {
bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), selectedImage);
ContextWrapper cw = new ContextWrapper(getApplicationContext());
// path to /data/data/yourapp/app_data/imageDir
File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
// Create imageDir
File mypath=new File(directory,"profile.jpg");
FileOutputStream fos = null;
try {
fos = new FileOutputStream(mypath);
// Use the compress method on the BitMap object to write image to the OutputStream
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
directory.getAbsolutePath();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
在我的清单中，我也有权限：
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".activities.LoginActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".activities.RegisterActivity"
android:screenOrientation="portrait" />
<activity
android:name=".activities.CategoryActivity"
android:screenOrientation="portrait" />
<activity android:name=".activities.SuggestionActivity" />
<activity
android:name=".activities.DetailActivity"
android:theme="@style/AppTheme" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
</application>
不过，单击按钮时出现此错误（设备为 API 24）：
06-08 19:56:28.903 18770-18782/android.process.media E/DatabaseUtils: Writing exception to parcel
java.lang.SecurityException: Permission Denial: reading com.android.providers.media.MediaProvider uri content://media/external/file from pid=20240, uid=10046 requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission()
at android.content.ContentProvider.enforceReadPermissionInner(ContentProvider.java:608)
at android.content.ContentProvider$Transport.enforceReadPermission(ContentProvider.java:483)
at android.content.ContentProvider$Transport.query(ContentProvider.java:212)
at android.content.ContentProviderNative.onTransact(ContentProviderNative.java:112)
at android.os.Binder.execTransact(Binder.java:565)