Android 从相册中选择图片

public class MainActivity4 extends AppCompatActivity {

    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);
        imageView = findViewById(R.id.image);
        Button resourcesBtn = findViewById(R.id.button2);

        resourcesBtn.setOnClickListener((v)->{
            Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
            intent.addCategory(Intent.CATEGORY_OPENABLE);
            intent.setType("image/*");
            startActivityForResult(intent,2);
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode){
            case 2:
                if (resultCode == Activity.RESULT_OK && data!=null){
                    try {
                        Bitmap bitmap = getBitmapFromUri(data.getData());
                        imageView.setImageBitmap(bitmap);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    }
                }
                break;
        }
    }

    private Bitmap getBitmapFromUri(Uri uri) throws FileNotFoundException {
        ParcelFileDescriptor parcelFileDescriptor = getContentResolver().openFileDescriptor(uri, "r");
        return BitmapFactory.decodeFileDescriptor(parcelFileDescriptor.getFileDescriptor());
    }
}

这样点击按钮就能跳转到相册界面，选择图片后会显示在imageView上

在相册选择完返回到Activity的是Uri，使用内容解析器等顺着Uri拿图片（Bitmap）显示到imageView上