How to build React-Native behind proxy

Recently I tried to setup and build react-native app (mostly for Android), behind a proxy server. To pass the gradle build, need set proxy config as below:

• Edit AwesomeProject\Android\gradle.properties, add proxy config:
•     systemProp.http.proxyHost=10.255.247.227
•     systemProp.http.proxyPort=8080
•     systemProp.https.proxyHost=10.255.247.227
    systemProp.https.proxyPort=8080

error: undefined reference to '__android_log_print' in Android Studio 2.1

Need load the android log lib in app/build.gradle:

    android.ndk {
        moduleName = "[the_module_name]"
        ldLibs.addAll(['android', 'log'])
    }

Make TextView scrollable without using ScrollView

2 steps, firstly, set scroll bar rotation in AndroidManifest.xml:
         android:scrollbars="vertical"

Then, set the scrolling method for the TextView, mostly in onCreate() function:
        ((TextView)findViewById(R.id.textview)).setMovementMethod(ScrollingMovementMethod.getInstance());

Parent Activity is destroyed when providing Up navigation

If providing Up navigation behavior as Android doc: http://developer.android.com/training/implementing-navigation/ancestral.html, when click the Up button on the navigation bar, the parent activity is destroyed then re-created. It is different behavior as pressing back key.

To avoid destroy parent activity, one solution is setting launch mode <singleTop> for the activity in AndroidManifest.xml:

android:launchMode="singleTop"

The different between Up key and Back key is, when pressing Back key, by default, the currently activity is popup from activity stack and finished, so the previously activity shows up. When pressing Up key, the currently activity is popup from stack too, but the parent activity, which is defined in AndroidManifest.xml and maybe not the previously activity, is created to show. By default the launch mode is <standard> so the existed activity task is destroyed then re-create. To set the launch mode to <singleTop>, Android will launch the existed one instead of create a new task.

Get Android Kernel log

 To catch Kernel log, need a rooted Android device and adb shell worable, then use the adb logcat command:

$adb shell logcat -v time -f /dev/kmsg | cat /proc/kmsg

To  write the output to a file:

$adb shell logcat -v time -f /dev/kmsg | cat /proc/kmsg > /sdcard/log.txt

Get navigation bar (TSB bar) height

The dim value is defined as com.android.internal.R.dimen.navigation_bar_height.

 final int naviHeight = mContext.getResources().getDimensionPixelSize(
                    com.android.internal.R.dimen.navigation_bar_height);

How to exclude activity from recent application list on Android

To forbidden your activity in the recent application list, just define this parameter in AndroidManifest.xml for the activity:

android:excludeFromRecents="true"

for example:
        <activity
            android:name="com.test.MainActivity"
            android:noHistory="true"
            android:screenOrientation="portrait"
            android:excludeFromRecents="true"
            android:label="@string/app_name">
            ......
         </activity>