github.com/SkycoinProject/gomobile@v0.0.0-20190312151609-d3739f865fa6/app/GoNativeActivity.java

package org.golang.app;

import android.app.Activity;
import android.app.NativeActivity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyCharacterMap;

public class GoNativeActivity extends NativeActivity {
	private static GoNativeActivity goNativeActivity;

	public GoNativeActivity() {
		super();
		goNativeActivity = this;
	}

	String getTmpdir() {
		return getCacheDir().getAbsolutePath();
	}

	static int getRune(int deviceId, int keyCode, int metaState) {
		try {
			int rune = KeyCharacterMap.load(deviceId).get(keyCode, metaState);
			if (rune == 0) {
				return -1;
			}
			return rune;
		} catch (KeyCharacterMap.UnavailableException e) {
			return -1;
		} catch (Exception e) {
			Log.e("Go", "exception reading KeyCharacterMap", e);
			return -1;
		}
	}

	private void load() {
		// Interestingly, NativeActivity uses a different method
		// to find native code to execute, avoiding
		// System.loadLibrary. The result is Java methods
		// implemented in C with JNIEXPORT (and JNI_OnLoad) are not
		// available unless an explicit call to System.loadLibrary
		// is done. So we do it here, borrowing the name of the
		// library from the same AndroidManifest.xml metadata used
		// by NativeActivity.
		try {
			ActivityInfo ai = getPackageManager().getActivityInfo(
					getIntent().getComponent(), PackageManager.GET_META_DATA);
			if (ai.metaData == null) {
				Log.e("Go", "loadLibrary: no manifest metadata found");
				return;
			}
			String libName = ai.metaData.getString("android.app.lib_name");
			System.loadLibrary(libName);
		} catch (Exception e) {
			Log.e("Go", "loadLibrary failed", e);
		}
	}

	@Override
	public void onCreate(Bundle savedInstanceState) {
		load();
		super.onCreate(savedInstanceState);
	}
}