Question

我有一个ArrayList的自定义对象，它是图像对象，它将以字符串形式存储图像Uri。当我通过使用ArrayList Uri中的setImageUri()显示图像时，它可以正确显示图像，但是使用ArrayList将SharedPreferences保存到Gson之后，并且从SharedPreferences中获取了这个ArrayList之后，在onCreate()中，它不在imageview中显示图像。我调试了代码，从SharedPreferences正确获取了Uri，但是为什么它没有显示图像。

这是我的 GridViewActivity 代码：

public class GridViewActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_grid_view);
        recyclerView=findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        autoFitGridLayoutManager=new AutoFitGridLayoutManager(context,250);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setLayoutManager(autoFitGridLayoutManager);
        arrayList=new ArrayList<>();
        sharedPref=new SharedPref(context);
        if (sharedPref.getCount()==0) {
            Toast.makeText(context, "No images...", Toast.LENGTH_SHORT).show();
        }
        else {
            Gson gson=new Gson();
            String response=sharedPref.getImages();
            arrayList=gson.fromJson(response,new TypeToken<ArrayList<Images>>(){}.getType()); //getting arraylist back
            Log.d("ROHIT", String.valueOf(arrayList.size())); //it displays the arraylist size correctly
            Images images=arrayList.get(0);
            Log.d("ROHIT","aya: "+images.getImage()); //Uri is also correct

            Intent intent=new Intent(context,Temp.class);
            intent.putExtra("image",images.getImage()); //passing it to the Temp activity
            startActivity(intent);
        }
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId()==R.id.add_imges_cam) {
            //open camera
        }
        else if(item.getItemId()==R.id.add_imges_gallery) {
            //open gallery to select images
            Intent intent = new Intent();
            intent.setType("image/*");
            intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
            intent.setAction(Intent.ACTION_GET_CONTENT);
            startActivityForResult(Intent.createChooser(intent,"Select Picture"), PICK_IMAGE_MULTIPLE);
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        int count=0;
        if(requestCode==PICK_IMAGE_MULTIPLE && resultCode==RESULT_OK) {
            String[] filePath = {MediaStore.Images.Media.DATA};

            if (data.getData() != null) {
                //if single image is selected
                Uri imageUri = data.getData();
                Cursor cursor = getContentResolver().query(imageUri, filePath, null, null, null);
                cursor.moveToFirst();
                arrayList.add(new Images(imageUri.toString()));
                cursor.close();
            } else {
                if (data.getClipData() != null) {
                    ClipData mClipData = data.getClipData();
                    for (int i = 0; i < mClipData.getItemCount(); i++) {
                        ClipData.Item item = mClipData.getItemAt(i);
                        Uri uri = item.getUri();
                        // Get the cursor
                        Cursor cursor = getContentResolver().query(uri, filePath, null, null, null);
                        // Move to first row
                        cursor.moveToFirst();
                        arrayList.add(new Images(uri.toString()));
                        count++;
                        cursor.close();
                    }
                }
            }
            imagesAdapter=new ImagesAdapter(context,arrayList);
            Images images=arrayList.get(0);

            Intent intent=new Intent(context,Temp.class); //when i called Temp activity before saving arraylist to sharedPref it displays image correctly in Temp activity
            intent.putExtra("image",images.getImage());
            startActivity(intent);

            sharedPref.save(arrayList); //saving arraylist to sharedPref
            sharedPref.updateCount(count);
            setRecyclerView();
        }
    }

}

这是我的 SharedPref 代码

public class SharedPref {
    SharedPreferences sharedPreferences;
    SharedPreferences.Editor editor;
    Context context;

    public SharedPref(Context context) {
        this.context=context;
        sharedPreferences=context.getSharedPreferences("Grid_images",Context.MODE_PRIVATE);
        editor=sharedPreferences.edit();
    }

    public void save(ArrayList<Images> arrayList) {
        Gson gson=new Gson();
        Object src;
        String json=gson.toJson(arrayList);
        editor.putString("grid_images",json);
        editor.apply();
        editor.commit();
    }

    public void updateCount(int i) {
        editor.putInt("images_count",i);
        editor.apply();
        editor.commit();
    }

    public int getCount() {
        return sharedPreferences.getInt("images_count",0);
    }

    public String getImages() {
        return sharedPreferences.getString("grid_images",null);
    }

    public void clearData() {
        editor.clear();
        editor.commit();
    }
}

这是临时类代码

public class Temp extends AppCompatActivity {
    ImageView imageView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_temp);
        imageView=findViewById(R.id.im_temp);
        Log.d("ROHIT","inside tmep: "+getIntent().getStringExtra("image"));
        imageView.setImageURI(Uri.parse(getIntent().getStringExtra("image")));
    }
}

Answer 1

您是否在清单文件中添加了权限READ_EXTERNAL_STORAGE？

使用Gson从SharedPreferences中获取Uri字符串后，setImageUri（）未显示图像

1 个答案: