getDrawingCache()方法获取bitmap 一直为空

添加权限

<!-- 允许程序写入外部存储，如SD卡上写文件-->

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

<!--    读取外置存储权限-->

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

application中 添加节点 android:requestLegacyExternalStorage="true"  （targetSdkVersion >= 29   此节点不添加一直为null亲测  坑呀）

---

屏幕截图 或者 view截图均可 

1.动态获取存储权限

if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP) {

int permission = ActivityCompat.checkSelfPermission(context,Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {

        ActivityCompat.requestPermissions(CropDetailsActivity.this, PERMISSIONS_STORAGE,

                REQUEST_PERMISSION_CODE);

    }else {

//获取到权限进行图片保存

Bitmap bmp =convertViewToBitmap(mSharePopLayout);

saveImageToGallery(bmp);

    }

}

---

（view可用当前页面布局id或者子view布局id）

public static BitmapconvertViewToBitmap(View view) {

view.measure(View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED), View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));

    view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());

    view.buildDrawingCache();

    Bitmap bitmap = view.getDrawingCache();

    return bitmap;

}

---

@Override

public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

super.onRequestPermissionsResult(requestCode, permissions, grantResults);

    if (requestCode ==REQUEST_PERMISSION_CODE) {

getShareImg();

    }else {

ToastUtils.show(context, "拒绝储存，前往设置打开读写权限");

    }

}

---

private void saveImageToGallery(Bitmap bmp) {

// 首先保存图片

    File appDir =new File(Environment.getExternalStorageDirectory(), "名称自拟");

    if (!appDir.exists()) {

appDir.mkdir();

    }

String fileName ="图片名称自拟";

    File file =new File(appDir, fileName);

    try {

FileOutputStream fos =new FileOutputStream(file);

        bmp.compress(Bitmap.CompressFormat.JPEG, 100, fos);

        fos.flush();

        fos.close();

    }catch (FileNotFoundException e) {

e.printStackTrace();

    }catch (IOException e) {

e.printStackTrace();

    }

// 其次把文件插入到系统图库

    try {

MediaStore.Images.Media.insertImage(this.getContentResolver(),

                file.getAbsolutePath(), fileName, null);

    }catch (FileNotFoundException e) {

e.printStackTrace();

    }

// 最后通知图库更新

    ToastUtils.show(context, "保存成功");

}