android listView 自定义布局结合CheckedTextView实现多选

最终效果图如下：

apiDemo中有一个listView实现多选的例子 

比较简单

 package com.example.android.apis.view;

 import android.app.ListActivity;
 import android.os.Bundle;
 import android.widget.ArrayAdapter;
 import android.widget.ListView;

 /**
  * This example shows how to use choice mode on a list. This list is
  * in CHOICE_MODE_MULTIPLE mode, which means the items behave like
  * checkboxes.
  */
 public class List11 extends ListActivity {

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

         setListAdapter(new ArrayAdapter(this,
                 android.R.layout.simple_list_item_multiple_choice, GENRES));

         final ListView listView = getListView();

         listView.setItemsCanFocus(false);
         listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
     }


     private static final String[] GENRES = new String[] {
         "Action", "Adventure", "Animation", "Children", "Comedy", "Documentary", "Drama",
         "Foreign", "History", "Independent", "Romance", "Sci-Fi", "Television", "Thriller"
     };
 }

利用了framework中的布局 simple_list_item_multiple_choice.xml ，该布局内容就是一个CheckedTextView

 <CheckedTextView xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@android:id/text1"
     android:layout_width="match_parent"
     android:layout_height="?android:attr/listPreferredItemHeight"
     android:textAppearance="?android:attr/textAppearanceLarge"
     android:gravity="center_vertical"
     android:checkMark="?android:attr/listChoiceIndicatorMultiple"
     android:paddingLeft="6dip"
     android:paddingRight="6dip"
 />

在实际的应用中我们肯定会遇到复杂布局的情况，一旦使用复杂布局，发现listview原生的多选模式失效了！失效原因通过查看ListView的源码可以发现，问题出在setupChild函数中

 private void setupChild(View child, int position, int y, boolean flowDown,int childrenLeft, boolean selected, boolean recycled) {
         ..................
         if (mChoiceMode != CHOICE_MODE_NONE && mCheckStates != null) {
             if (child instanceof Checkable) {
                 ((Checkable) child).setChecked(mCheckStates.get(position));
             }
         }
     }

其中的child对象就是自定义adapter的getView()函数的返回结果，由于我们没有实现Checkable接口所以无法操作。变通办法，ListView有一个察看item是否被选中的函数，结合该函数，修改自定义adapter的getView函数：

 public View getView(int position, View convertView, ViewGroup parent) {
         boolean check = ((ListView)parent).isItemChecked(position);
         viewHolder.myCheckedTextView.setChecked(check);
     ｝