如何保存新的图像按钮图片并在重新启动时加载新创建的图像按钮图像

Question

一旦应用程序关闭，我正在尝试重新加载从我的画廊或相机中的图像按钮中获取的图像

我尝试将它保存到一个文件并从该文件加载，但我无法让它工作。

public class HomeFragment extends Fragment {


    ImageButton profilePic;

    Drawable myDrawable;
    Bitmap bitmap ;




    String photoPath = Environment.getExternalStorageDirectory().toString();

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
               View root = inflater.inflate(R.layout.fragment_home, container, false);



       profilePic = (ImageButton) root.findViewById(R.id.imageButton);
        myDrawable = profilePic.getBackground();
        bitmap = drawableToBitmap(myDrawable);


// set up listener on ImageButton to load method changeProfilePicture() when user clicks profilePic
        profilePic.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                changeProfilePicture();
            }
        });


        int Permission_All = 1;

        String[] Permissions = {Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE};
        if(!hasPermissions(getActivity(), Permissions)){
            ActivityCompat.requestPermissions(getActivity(), Permissions, Permission_All);

        }


       loadImageFromStorage(photoPath);
        return root;

    }


    public void onResume() {

        super.onResume();

        loadImageFromStorage(photoPath);

    }

    public void onStart() {

        super.onStart();

    }

    public void onPause() {

        super.onPause();


    }

    public void onStop() {

        super.onStop();

        saveBitmap(bitmap);
    }

    public void onDestroy() {

        super.onDestroy();


    }

    static final int REQUEST_IMAGE_CAPTURE = 1;
    static final int REQUEST_GALLERY = 0;

    //create changeProfilePicture method and call it when the  ImageButton is pressed
    public void changeProfilePicture() {

// add alert dialog to ask user how they would like to change their profile icon



    }


    // override onActivityResult to allow the imageButton to be changed to picture taken from camera or gallery

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(resultCode == RESULT_OK) {
            //create a switch based on requestCode
            switch (requestCode) {
                // if user clicks change profilePic through gallery use picture user picked from gallery
                case REQUEST_GALLERY:
                    Uri galleryImage = data.getData();
                    try {
                        Bitmap galleryBitmap = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), galleryImage);
                        galleryBitmap = Bitmap.createScaledBitmap(galleryBitmap, 200, 200, false);
                        profilePic.setImageBitmap(galleryBitmap);
                       saveBitmap(galleryBitmap);
                    } catch (IOException e) {
                        Log.i("TAG", "Exception " + e);
                    }

                    break;
                // if user clicks change profilePic through camera use picture user took from camera app

                case REQUEST_IMAGE_CAPTURE:

                    Bundle extras = data.getExtras();
                    Bitmap imageBitmap = (Bitmap) extras.get("data");
                    imageBitmap = Bitmap.createScaledBitmap(imageBitmap, 200, 200, false);
                    profilePic.setImageBitmap(imageBitmap);
                    saveBitmap(imageBitmap);

                    break;
            }

        }
    }



    private void saveBitmap(Bitmap bm){
        File file = Environment.getExternalStorageDirectory();
        File newFile = new File(file, "myImage.jpg");

        try {
            FileOutputStream fileOutputStream = new FileOutputStream(newFile);
            bm.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);
            fileOutputStream.flush();
            fileOutputStream.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        Log.i( "getExternalStorageDirectory", file.getPath()) ;
    }

    private void loadImageFromStorage(String path)
    {

        try {
            File f=new File(path, "myImage.jpg");
            Bitmap b = BitmapFactory.decodeStream(new FileInputStream(f));
            profilePic.setImageBitmap(b);
        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        }

    }

    public static Bitmap drawableToBitmap (Drawable drawable) {
        Bitmap bitmap = null;

        if (drawable instanceof BitmapDrawable) {
            BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
            if(bitmapDrawable.getBitmap() != null) {
                return bitmapDrawable.getBitmap();
            }
        }

        if(drawable.getIntrinsicWidth() <= 0 || drawable.getIntrinsicHeight() <= 0) {
            bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);
        } else {
            bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
        }

        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        drawable.draw(canvas);
        return bitmap;
    }

    public static boolean hasPermissions(Context context, String... permissions)
    {

        if(Build.VERSION.SDK_INT>= Build.VERSION_CODES.M && context!=null && permissions!=null){
            for(String permission: permissions){
                if(ActivityCompat.checkSelfPermission(context, permission)!= PackageManager.PERMISSION_GRANTED){
                    return  false;
                }
            }
        }
        return true;
    }

}



// what I have for my ImageButton in xml

   <ImageButton
        android:id="@+id/imageButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:contentDescription="@string/profilePic"
        android:onClick="changeProfilePicture"
        android:paddingLeft="0dp"
        android:paddingTop="0dp"
        android:paddingRight="0dp"
        android:paddingBottom="0dp"
        android:layout_marginTop="2dp"
        android:layout_marginBottom="5dp"
        android:background="#0000"
        app:srcCompat="@mipmap/ic_launcher_round" />

I have the following permissions inside the manifest.xml 

 <uses-feature
        android:name="android.hardware.camera"
        android:required="true" /> 
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

我正在尝试从我的结果中保存新的 ImageButton 并在重新启动应用程序时加载它。这可以用 ImageButton 完成吗？它可以保存到文件中并从文件中加载吗？

Answer 1

作为第一步，您需要像这样从imageButton 获取位图

Bitmap bitmap = ((BitmapDrawable)imageButton.getDrawable()).getBitmap();

接下来你需要像这样将该位图保存到外部存储中

private void saveBitmap(Bitmap bm){
    File file = Environment.getExternalStorageDirectory();
    File newFile = new File(file, "myImage.jpg");

    try {
        FileOutputStream fileOutputStream = new FileOutputStream(newFile);
        bm.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);
        fileOutputStream.flush();
        fileOutputStream.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

然后你像这样加载这个保存的位图

private void loadImageFromStorage(String path)
{

    try {
        File f=new File(path, "myImage.jpg");
        Bitmap b = BitmapFactory.decodeStream(new FileInputStream(f));
        imageButton.setImageBitmap(b);
    } 
    catch (FileNotFoundException e) 
   {
    e.printStackTrace();
   }

}

你应该像这样定义图像路径

String photoPath = Environment.getExternalStorageDirectory() + "/myImage.jpg";

这是主要思想，当没有可用的图像保存时，您可以通过设置默认图像来为这段代码添加一点味道。

希望这就是我们想要的。

更新：

你需要改变这一行

Bitmap bitmap = ((BitmapDrawable)imageButton.getDrawable()).getBitmap();

到这里

Drawable myDrawable = imageButton.getBackground();

之后，您将此 Drawable 转换为 Bitmap

Bitmap bitmap = drawableToBitmap(myDrawable);

这是这个转换的函数

public static Bitmap drawableToBitmap (Drawable drawable) {
    Bitmap bitmap = null;

    if (drawable instanceof BitmapDrawable) {
        BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
        if(bitmapDrawable.getBitmap() != null) {
            return bitmapDrawable.getBitmap();
        }
    }

    if(drawable.getIntrinsicWidth() <= 0 || drawable.getIntrinsicHeight() <= 0) {
        bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888); 
    } else {
        bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
    }

    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);
    return bitmap;
}

更新 2：

您需要请求运行时权限才能保存和检索图像 首先你需要把它添加到你的清单文件中

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

接下来将此方法添加到您的活动中

public static boolean hasPermissions(Context context, String... permissions)
{

    if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.M && context!=null && permissions!=null){
        for(String permission: permissions){
            if(ActivityCompat.checkSelfPermission(context, permission)!= PackageManager.PERMISSION_GRANTED){
                return  false;
            }
        }
    }
    return true;
}

最后在您的onCreate 中添加这些行

int Permission_All = 1;

    String[] Permissions = {Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE};
    if(!hasPermissions(this, Permissions)){
        ActivityCompat.requestPermissions(this, Permissions, Permission_All);
    }