Android 在活动上保留图像

我使用此代码从设备中拾取图像，但当活动关闭时，图像消失。如何保存它，以便每当我打开活动时图像仍在那里

 @Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {

    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
        case RESULT_LOAD_IMAGE:
            if (resultCode == RESULT_OK && data!= null) {
                Uri imageData = data.getData() ;
                imageView.setImageURI(imageData);



            }

    }
}

---

因此，您需要的是将选定的imageUri保存在活动的本地首选项中

请检查以下代码：

public class Prefs {
private static Prefs INSTANCE;
private static SharedPreferences prefs;

public static Prefs getInstance(Context context) {
    if (INSTANCE == null) {
        INSTANCE = new Prefs();
        prefs = context.getSharedPreferences("prefs", Context.MODE_PRIVATE);
    }

    return INSTANCE;
}

  public void setImage(String image) {
    prefs.edit().putString("image", image).apply();
}

public String getImage() {
    return prefs.getString("image", "");
}

然后在您的活动中：

    @Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout);


if(!TextUtils.isEmpty(Prefs.getInstance(applicationContext).getImage()){

val imgFile = File(Prefs.getInstance(getApl).getImage())

            if (imgFile.exists()) {
                val myBitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath())
                imageView.setImageBitmap(myBitmap)
            }
}

在onActivityResult中：

 @Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {

super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
    case RESULT_LOAD_IMAGE:
        if (resultCode == RESULT_OK && data!= null) {
            Uri imageData = data.getData() ;
            imageView.setImageURI(imageData);
Prefs.getInstance(applicationContext).setImage(PathUtils.getPath(applicationContext,imageData));


        }

}
}


public class PathUtils {

public static String getPath(final Context context, final Uri uri) {

    // DocumentProvider
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT && DocumentsContract.isDocumentUri(context, uri)) {

        if (isExternalStorageDocument(uri)) {// ExternalStorageProvider
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];
            String storageDefinition;


            if ("primary".equalsIgnoreCase(type)) {

                return Environment.getExternalStorageDirectory() + "/" + split[1];

            } else {

                if (Environment.isExternalStorageRemovable()) {
                    storageDefinition = "EXTERNAL_STORAGE";

                } else {
                    storageDefinition = "SECONDARY_STORAGE";
                }

                return System.getenv(storageDefinition) + "/" + split[1];
            }

        } else if (isDownloadsDocument(uri)) {// DownloadsProvider

            final String id = DocumentsContract.getDocumentId(uri);
            final Uri contentUri = ContentUris.withAppendedId(
                    Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

            return getDataColumn(context, contentUri, null, null);

        } else if (isMediaDocument(uri)) {// MediaProvider
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            Uri contentUri = null;
            if ("image".equals(type)) {
                contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
            } else if ("video".equals(type)) {
                contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
            } else if ("audio".equals(type)) {
                contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
            }

            final String selection = "_id=?";
            final String[] selectionArgs = new String[]{
                    split[1]
            };

            return getDataColumn(context, contentUri, selection, selectionArgs);
        }

    } else if ("content".equalsIgnoreCase(uri.getScheme())) {// MediaStore (and general)

        // Return the remote address
        if (isGooglePhotosUri(uri))
            return uri.getLastPathSegment();

        return getDataColumn(context, uri, null, null);

    } else if ("file".equalsIgnoreCase(uri.getScheme())) {// File
        return uri.getPath();
    }

    return null;
}

public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {

    Cursor cursor = null;
    final String column = "_data";
    final String[] projection = {
            column
    };

    try {
        cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);
        if (cursor != null && cursor.moveToFirst()) {
            final int column_index = cursor.getColumnIndexOrThrow(column);
            return cursor.getString(column_index);
        }
    } finally {
        if (cursor != null)
            cursor.close();
    }
    return null;
}


public static boolean isExternalStorageDocument(Uri uri) {
    return "com.android.externalstorage.documents".equals(uri.getAuthority());
}


public static boolean isDownloadsDocument(Uri uri) {
    return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}

public static boolean isMediaDocument(Uri uri) {
    return "com.android.providers.media.documents".equals(uri.getAuthority());
}

public static boolean isGooglePhotosUri(Uri uri) {
    return "com.google.android.apps.photos.content".equals(uri.getAuthority());
}

---

}

首先，您必须使用光标来捕获媒体路径，然后您可以使用特殊键将其存储在hawk或共享首选项上。然后使用存储在Hawk或shared preferences中的数据打开图像。 例如：

---

原则上都可以。但你忘了告诉我，这不适用于行动内容。还有其他缺点，我不明白你的意思。即使应用程序已关闭和打开，用户也只想保存imageUrl。因此，这是最好的结果，但它不会起作用。您是否重新启动了应用程序并检查了图像是否从uri重新加载？您将返回uri。这是真的。但它是无用的，因为读取权限不再有效。但是您可以解决该问题。每个会话只需要一次读取权限。没有人每次都获得读取权限。无论如何，如果你有更好的解决方案，请回答问题。我认为这是可行的。您没有回答我的问题：

是否重新启动应用程序并检查图像是否从uri重新加载？

。请吧。

               Uri selectedImage = data.getData();
            String[] filePathColumn = {MediaStore.Images.Media.DATA};
             Cursor cursor = getContentResolver().query(selectedImage, 
             filePathColumn, null, null, null);
            cursor.moveToFirst();

            int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
            mediaPath = cursor.getString(columnIndex);
            Hawk.put("image",mediaPath);

            //after_reset =>
            String mediaPath1 = Hawk.get("image").toString();
            channelImage.setImageBitmap(BitmapFactory.decodeFile(mediaPath1));