ui代码注释

DropdownMenu.java

@@ -0,0 +1,63 @@
+/*
+ * 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.
+ */
+
+package net.micode.notes.ui;  // 定义类所在的包路径
+
+import android.content.Context;  // 引入Context类，用于访问应用程序的上下文
+import android.view.Menu;  // 引入Menu类，用于操作菜单
+import android.view.MenuItem;  // 引入MenuItem类，用于菜单项的处理
+import android.view.View;  // 引入View类，用于视图的操作
+import android.view.View.OnClickListener;  // 引入OnClickListener接口，用于处理点击事件
+import android.widget.Button;  // 引入Button类，用于显示按钮
+import android.widget.PopupMenu;  // 引入PopupMenu类，用于显示弹出菜单
+import android.widget.PopupMenu.OnMenuItemClickListener;  // 引入PopupMenu的菜单项点击监听器
+
+public class DropdownMenu {
+    private Button mButton;  // 用于显示的按钮，点击后弹出菜单
+    private PopupMenu mPopupMenu;  // 弹出菜单的实例
+    private Menu mMenu;  // 菜单项的集合
+
+    // 构造函数，初始化DropdownMenu，设置按钮及其弹出菜单
+    public DropdownMenu(Context context, Button button, int menuId) {
+        mButton = button;  // 获取传入的按钮对象
+        mButton.setBackgroundResource(R.drawable.dropdown_icon);  // 设置按钮的背景图标为下拉菜单图标
+        mPopupMenu = new PopupMenu(context, mButton);  // 初始化PopupMenu，指定按钮作为弹出菜单的锚点
+        mMenu = mPopupMenu.getMenu();  // 获取PopupMenu中的Menu对象
+        mPopupMenu.getMenuInflater().inflate(menuId, mMenu);  // 使用传入的menuId加载菜单资源
+        mButton.setOnClickListener(new OnClickListener() {  // 为按钮设置点击事件监听器
+            public void onClick(View v) {
+                mPopupMenu.show();  // 当按钮被点击时，显示弹出菜单
+            }
+        });
+    }
+
+    // 设置菜单项点击事件监听器
+    public void setOnDropdownMenuItemClickListener(OnMenuItemClickListener listener) {
+        if (mPopupMenu != null) {
+            mPopupMenu.setOnMenuItemClickListener(listener);  // 设置PopupMenu的菜单项点击监听器
+        }
+    }
+
+    // 根据菜单项的ID查找菜单项
+    public MenuItem findItem(int id) {
+        return mMenu.findItem(id);  // 在菜单中查找具有指定ID的菜单项
+    }
+
+    // 设置按钮的文本
+    public void setTitle(CharSequence title) {
+        mButton.setText(title);  // 设置按钮的文本为传入的title
+    }
+}