用ExpandableListView实现类似QQ好友列表

ExpandableListView是一个用来显示二级节点的listview。

qq好友列表中子列表上下移动时，父节点在顶端会始终显示，这里我们可以自定义一个view来充当这个父节点。

主布局文件qq_listview如下,其中当我们拖动列表时，系统默认拖动过程中列表背景是黑的，我们可以通过android:cacheColorHint="#00000000"将其设置为透明，其中前两位是透明效果参数（00-99），后六位是颜色的设置。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:orientation="vertical"
  android:background="@drawable/default_bg_hdpi">
  <LinearLayout
  	 android:id="@+id/gone_linear"
 	 android:layout_width="fill_parent"
 	 android:layout_height="wrap_content"
 	 android:background="@drawable/expand_column_bg"
 	 android:visibility="gone"
 	 android:cacheColorHint="#50000000"
  >
  <ImageView android:id="@+id/qq_list_imageview" 
  	android:layout_width="wrap_content"  android:layout_height="30dip" 
  	android:src="@drawable/narrow_select" />
  <TextView android:id="@+id/qq_list_textview"   android:layout_marginLeft="50dip"
  	android:layout_width="fill_parent" android:layout_height="wrap_content" />
  	</LinearLayout>
	<FrameLayout android:layout_width="fill_parent"
		android:layout_height="fill_parent">
  <ExpandableListView android:id="@+id/qq_listview"
 	 android:cacheColorHint="#00000000"
  	android:layout_width="fill_parent" android:layout_height="wrap_content" />
  	</FrameLayout>
</LinearLayout>

如果我们想更换父节点打开和关闭时的箭头，可以先设置一个selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
	<item android:state_window_focused="false" android:drawable="@drawable/expand_column_bg_over" />
	<item android:state_pressed="true" android:drawable="@drawable/expand_column_bg" />
	<item android:state_pressed="false" android:drawable="@drawable/feedlistdividerbg"></item>
</selector>

 然后在代码中调用

		elistview = (ExpandableListView)findViewById(R.id.qq_listview);
		//替换ExpandableListView的打开关闭时的箭头图标
		elistview.setGroupIndicator(this.getResources().getDrawable(R.drawable.expand_list_selector));

此外，我们还要设置父节点和子节点item的布局文件

父节点qq_list_parent.xml如下

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent" 	
  android:background="@drawable/expand_column_bg">
  <TextView android:id="@+id/parend"
  	android:layout_width="wrap_content" 
  	android:layout_height="30dip"
  	android:layout_marginLeft="50dip"
  	 />
</LinearLayout>

子节点qq_listview_child.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:cacheColorHint="#00000000"
 >
    <TextView android:id="@+id/child"
  		android:layout_width="wrap_content" android:layout_height="40dip"
  		android:layout_marginLeft="80dip"
  		/>
</LinearLayout>

java代码如下

package com.sy.android.qqlistview;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnGroupCollapseListener;
import android.widget.ExpandableListView.OnGroupExpandListener;
import android.widget.LinearLayout;
import android.widget.SimpleExpandableListAdapter;
import android.widget.TextView;

import com.sy.android.testAndroid.R;

public class QQListView extends Activity   {
	
	private static ArrayList<Map<String,String>> parentData = new ArrayList<Map<String,String>>();
	private static ArrayList<ArrayList<Map<String,String>>> childData = new ArrayList<ArrayList<Map<String,String>>>();
	private ExpandableListView elistview;
	private TextView tv;
	
	/**
	 *当前打开的父节点
	 */
	private int the_group_expand_position=-1;
	/**
	 * 打开的父节点所与的子节点数
	 */
	private int position_child_count=0;
	/**
	 * 是否有打开的父节点
	 */
	private boolean isExpanding=false;
	
	public void getData(){
		for(int i=0; i<20;i++){
			 Map<String,String> map = new HashMap<String,String>();
			 map.put("parend", i+"");
			 parentData.add(map);
		}
		for(int i=0;i<20;i++){
			ArrayList<Map<String,String>> child = new ArrayList<Map<String,String>>();
			for(int j=0; j<20;j++){
				Map<String,String> map = new HashMap<String,String>();
				map.put("child", i+""+j);
				child.add(map);
			}
			childData.add(child);
		}
	}
	
	public void onCreate(Bundle saveBundle){
		super.onCreate(saveBundle);
		setContentView(R.layout.qq_listview);
		
		elistview = (ExpandableListView)findViewById(R.id.qq_listview);
		//替换ExpandableListView的打开关闭时的箭头图标
		elistview.setGroupIndicator(this.getResources().getDrawable(R.drawable.expand_list_selector));
		tv = (TextView)findViewById(R.id.qq_list_textview);
		
		/**
		 * 滑动子列表时在上方显示父节点的view
		 */
		final LinearLayout linear = (LinearLayout)findViewById(R.id.gone_linear);
		
		/**
		 * 监听父节点打开的事件
		 */
		elistview.setOnGroupExpandListener(new OnGroupExpandListener(){

			@Override
			public void onGroupExpand(int groupPosition) {
				the_group_expand_position=groupPosition;
				position_child_count=childData.get(groupPosition).size();
				isExpanding=true;
			}
			
		});
		
		/**
		 * 监听父节点关闭的事件
		 */
		elistview.setOnGroupCollapseListener(new OnGroupCollapseListener(){

			@Override
			public void onGroupCollapse(int groupPosition) {
				if(linear.getVisibility()==View.VISIBLE){
					linear.setVisibility(View.GONE);
				}
				isExpanding=false;
			}
			
		});
		

		linear.setOnClickListener(new OnClickListener(){

			@Override
			public void onClick(View v) {
				linear.setVisibility(View.GONE);
				elistview.collapseGroup(the_group_expand_position);
			}
			
		});
		
		/**
		 * 通过setOnScrollListener来监听列表上下滑动时item显示和消失的事件
		 */
		
		elistview.setOnScrollListener(new OnScrollListener(){

			@Override
			public void onScrollStateChanged(AbsListView view, int scrollState) {
				
			}

			@Override
			public void onScroll(AbsListView view, int firstVisibleItem,
					int visibleItemCount, int totalItemCount) {
				if(isExpanding){
					// 当当前第一个item id小于打开的父节点id 或大于打开的父节点id和它的子节点总数之和时
					if(firstVisibleItem<the_group_expand_position ||
							firstVisibleItem>(the_group_expand_position+position_child_count)){
						linear.setVisibility(View.GONE);
					}else{
						linear.setVisibility(View.VISIBLE);
						tv.setText(((Map)parentData.get(the_group_expand_position)).get("parend").toString());
					}
				}
			}
			
		});
		
		getData();
		
		SimpleExpandableListAdapter selAdapter = new SimpleExpandableListAdapter(this,
				parentData,
				R.layout.qq_listview_parend_item,
				new String[]{"parend"},
				new int[]{R.id.parend},
				childData,
				R.layout.qq_liatview_child_item,
				new String[]{"child"},
				new int[]{R.id.child}
				);
		elistview.setAdapter(selAdapter);

	}

}

实现的思路是通过setOnScrollListener来监听listview，从而获得显示在视图中的item的id,通过id的判断来决定显示在顶端的自定义的view是否显示