feat: MainActivity工具栏添加About按钮跳转AboutActivity窗口

- 新增菜单资源文件 res/menu/menu_main.xml
- MainActivity 添加 onCreateOptionsMenu() 加载菜单
- MainActivity 添加 onOptionsItemSelected() 处理 About 按钮点击事件
- 点击 About 按钮后通过 Intent 启动 AboutActivity

gpsrelaysentinel/src/main/java/cc/winboll/studio/gpsrelaysentinel/MainActivity.java

@@ -14,6 +14,8 @@ import android.widget.EditText;
 import android.widget.Spinner;
 import android.widget.Switch;
 import android.widget.TextView;
+import android.view.Menu;
+import android.view.MenuItem;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
 import cc.winboll.studio.gpsrelaysentinel.R;
@@ -141,6 +143,21 @@ public final class MainActivity extends AppCompatActivity {
         setSupportActionBar(mToolbar);
     }
 
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.menu_main, menu);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        if (item.getItemId() == R.id.action_about) {
+            startActivity(new Intent(this, AboutActivity.class));
+            return true;
+        }
+        return super.onOptionsItemSelected(item);
+    }
+
     /**
      * GPS服务开关监听
      */

gpsrelaysentinel/src/main/res/menu/menu_main.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+      xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/action_about"
+        android:title="About"
+        android:icon="@android:drawable/ic_menu_info_details"
+        app:showAsAction="ifRoom"/>
+</menu>