android 8.0安装未知应用

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

boolean hasInstallPermission = mContext.getPackageManager().canRequestPackageInstalls();
Intent intent = new Intent(Settings.ACTION_MANAGE_UNKNOWN_APP_SOURCES);  
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);  
mContext.startActivity(intent);