添加代码注释

src/Notes-master/app/src/main/java/net/micode/notes/ui/DropdownMenu.java

@@ -1,17 +1,9 @@
 /*
  * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
  *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *        http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * 版权声明：本代码受Apache许可证2.0版本保护
+ * 您可以在遵守许可证的前提下使用、修改和分发本代码
+ * 许可证全文可在http://www.apache.org/licenses/LICENSE-2.0获取
  */
 
 package net.micode.notes.ui;
@@ -27,17 +19,38 @@ import android.widget.PopupMenu.OnMenuItemClickListener;
 
 import net.micode.notes.R;
 
+/**
+ * 下拉菜单控件
+ * 功能：封装PopupMenu，提供简洁的下拉菜单交互方式
+ * 特点：基于Button触发，支持自定义菜单项和点击事件
+ */
 public class DropdownMenu {
+    // 触发下拉菜单的按钮
     private Button mButton;
+    // 系统PopupMenu对象
     private PopupMenu mPopupMenu;
+    // 菜单项集合
     private Menu mMenu;
 
+    /**
+     * 构造函数
+     * @param context 上下文对象
+     * @param button 触发下拉菜单的按钮
+     * @param menuId 菜单资源ID
+     */
     public DropdownMenu(Context context, Button button, int menuId) {
         mButton = button;
+        // 设置按钮背景为下拉菜单图标
         mButton.setBackgroundResource(R.drawable.dropdown_icon);
+        
+        // 初始化PopupMenu
         mPopupMenu = new PopupMenu(context, mButton);
         mMenu = mPopupMenu.getMenu();
+        
+        // 从资源文件加载菜单项
         mPopupMenu.getMenuInflater().inflate(menuId, mMenu);
+        
+        // 设置按钮点击事件，显示下拉菜单
         mButton.setOnClickListener(new OnClickListener() {
             public void onClick(View v) {
                 mPopupMenu.show();
@@ -45,17 +58,30 @@ public class DropdownMenu {
         });
     }
 
+    /**
+     * 设置菜单项点击监听器
+     * @param listener 菜单项点击回调
+     */
     public void setOnDropdownMenuItemClickListener(OnMenuItemClickListener listener) {
         if (mPopupMenu != null) {
             mPopupMenu.setOnMenuItemClickListener(listener);
         }
     }
 
+    /**
+     * 查找指定ID的菜单项
+     * @param id 菜单项ID
+     * @return 对应的MenuItem对象，未找到则返回null
+     */
     public MenuItem findItem(int id) {
         return mMenu.findItem(id);
     }
 
+    /**
+     * 设置按钮标题
+     * @param title 要显示的标题文本
+     */
     public void setTitle(CharSequence title) {
         mButton.setText(title);
     }
-}
+}