Android的ToDoList(fragment) 詳解

Fragment(碎片) 可以靈活地從一個活動的Activity上添加或刪除Fragment, 有良好的用戶體驗;

下面是Fragment的具體設計:

1. 創建new_item_fragment的資源文件:

位置: res->new_item_fragment.xml

<?xml version="1.0" encoding="utf-8"?>  
      
<EditText xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/myEditText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="@string/addItemHint"
    android:contentDescription="@string/addItemContentDescription"
 />

包含一個EditText控件;

2. 創建NewItemFragment的邏輯實現:

位置: java->package->NewItemFragment.java

package mzx.spike.todolist.app;  
      
import android.app.Activity;  
import android.app.Fragment;  
import android.os.Bundle;  
import android.view.KeyEvent;  
import android.view.LayoutInflater;  
import android.view.View;  
import android.view.ViewGroup;  
import android.widget.EditText;  
      
/** 
 * Created by C.L.Wang on 14-3-14. 
 */
public class NewItemFragment extends Fragment{  
      
    private  OnNewItemAddedListener onNewItemAddedListener;  
      
    //監聽事件  
    public interface OnNewItemAddedListener {  
        public void onNewItemAdded(String newItem);  
    }  
      
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,  
                             Bundle savedInstanceState) {  
      
        View view = inflater.inflate(R.layout.new_item_fragment, container, false);  
      
        final EditText myEditText = (EditText)view.findViewById(R.id.myEditText);  
      
        //監聽事件  
        myEditText.setOnKeyListener(new View.OnKeyListener() {  
            @Override
            public boolean onKey(View view, int i, KeyEvent keyEvent) {  
                if (keyEvent.getAction() == KeyEvent.ACTION_DOWN)  
                    if ((i == KeyEvent.KEYCODE_DPAD_CENTER) ||  
                       (i == KeyEvent.KEYCODE_ENTER)) {  
                        String newItem = myEditText.getText().toString();  
                        onNewItemAddedListener.onNewItemAdded(newItem);  
                        myEditText.setText("");  
                        return true;  
                    }  
                return false;  
            }  
        });  
      
        return view;  
    }  
      
    //綁定到Activity  
    public void onAttach(Activity activity) {  
      
        super.onAttach(activity);  
      
        try {  
            onNewItemAddedListener = (OnNewItemAddedListener)activity;  
        } catch (ClassCastException e) {  
            throw new ClassCastException(activity.toString() + " must implement OnNewItemAddedListener");  
        }  
    }  
      
}

詳解:

1. 繼承Fragment類;

2. 監聽接口(interface OnNewItemListener), 包含一個監聽方法(onNewItemAdded), 然後實現一個實例;

3. 創建視圖(onCreateView), 需要返回一個視圖(View);

4. 填充一個視圖, 調用inflater.inflate()函數, 綁定fragment的資源文件;

5. 獲得控件的引用, view.findViewById(), 得到myEditText的引用;

6. 監聽事件, 監聽myEditText的輸入內容, 傳遞給接口的內容(new Item);

7. 使用onAttach()函數, 綁定Acitivity之後, 獲得activity的引用;

3. 創建ToDoListFragment的邏輯實現:

位置: java->package->ToDoListFragment.java

package mzx.spike.todolist.app;  
      
import android.app.ListFragment;  
      
/** 
 * Created by C.L.Wang on 14-3-14. 
 */
public class ToDoListFragment extends ListFragment{  
}

繼承ListFragment;

4. 創建activity_to_do_list資源文件, 即Activity資源文件:

位置: res->layout->activity_to_do_list.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="mzx.spike.todolist.app.ToDoListActivity">  
      
    <fragment android:name="mzx.spike.todolist.app.NewItemFragment"
        android:id="@+id/NewItemFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/addItemHint"
        android:contentDescription="@string/addItemContentDescription"
     />  
      
    <fragment android:name="mzx.spike.todolist.app.ToDoListFragment"
        android:id="@+id/ToDoListFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
     />  
      
</LinearLayout>

LinearLayout包含兩個fragment結點, 需要提供android:name的參數, 實現;