android开发 弹出权限提示框 检查是否具有某个权限

final private int REQUEST_CODE_ASK_PERMISSIONS = 123;//权限请求码

//在执行扫描二维码之前检查是否具有打开照相机的权限
try {
int hasWriteContactsPermission =context.checkSelfPermission(Manifest.permission.CAMERA);//权限检查
if (hasWriteContactsPermission != PackageManager.PERMISSION_GRANTED) {
requestPermissions(new String[] {Manifest.permission.CAMERA},
REQUEST_CODE_ASK_PERMISSIONS);
return;//没有权限，结束
}else {
//做自己的操作
}
} catch (Exception e) {
e.printStackTrace();
ToastUtil.defaultToast(getContext().getApplicationContext(), "权限异常");
}

//回调函数，无论用户是否允许都会调用执行此方法
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode) {
case REQUEST_CODE_ASK_PERMISSIONS:
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// Permission Granted 用户允许权限 继续执行（我这里执行的是二维码扫描，检查的是照相机权限）
Intent intent = new Intent(getActivity(),
CaptureActivity.class);
startActivityForResult(intent, REQUEST_CODE_SCAN);
} else {
// Permission Denied 拒绝
ToastUtil.defaultToast(context.getApplicationContext(),"获取权限失败，无法扫描");
}
break;
default:
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}

捉住demo一只，点击下载