android 实现QQ好友列表（扩展listview:ExpandableListView）

        在某些android开发群里，看到有些新手问怎么实现QQ好友列表，其实网上一搜挺多的。接触Android，也才一年的时间，大部分时间花在工作上（解bug。。。），界面上开发很少参与。自己维护的系统应用里，有个ExpandableListView的界面（其实android例子APIDemo也有类似的例子）就在这里写个Demo供新手参考。

        ExpandableListView的用法：难点就是重写BaseExpandableListAdapter及提供的数据源。

        下面看看继承BaseExpandableListAdapter的适配器：

<span xmlns="http://www.w3.org/1999/xhtml">package com.xyz.expande;

import java.util.List;

import android.app.AlertDialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class ExpandeAdapter extends BaseExpandableListAdapter {

    private Context mContext;
    private LayoutInflater mInflater = null;
    private String[] mGroupStrings = null;
    private List<List<Item>> mData = null;

    public ExpandeAdapter(Context ctx, List<List<Item>> list) {
        mContext = ctx;
        mInflater = (LayoutInflater) mContext
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mGroupStrings = mContext.getResources().getStringArray(R.array.groups);
        mData = list;
    }

    public void setData(List<List<Item>> list) {
        mData = list;
    }

    @Override
    public int getGroupCount() {
        // TODO Auto-generated method stub
        return mData.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        // TODO Auto-generated method stub
        return mData.get(groupPosition).size();
    }

    @Override
    public List<Item> getGroup(int groupPosition) {
        // TODO Auto-generated method stub
        return mData.get(groupPosition);
    }

    @Override
    public Item getChild(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        return mData.get(groupPosition).get(childPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        // TODO Auto-generated method stub
        return groupPosition;
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        return childPosition;
    }

    @Override
    public boolean hasStableIds() {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.group_item_layout, null);
        }
        GroupViewHolder holder = new GroupViewHolder();
        holder.mGroupName = (TextView) convertView
                .findViewById(R.id.group_name);
        holder.mGroupName.setText(mGroupStrings[groupPosition]);
        holder.mGroupCount = (TextView) convertView
                .findViewById(R.id.group_count);
        holder.mGroupCount.setText("[" + mData.get(groupPosition).size() + "]");
        return convertView;
    }

    @Override
    public View getChildView(int groupPosition, int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.child_item_layout, null);
        }
        ChildViewHolder holder = new ChildViewHolder();
        holder.mIcon = (ImageView) convertView.findViewById(R.id.img);
        holder.mIcon.setBackgroundDrawable(getRoundCornerDrawable(
                getChild(groupPosition, childPosition).getImageId(), 10));
        holder.mChildName = (TextView) convertView.findViewById(R.id.item_name);
        holder.mChildName.setText(getChild(groupPosition, childPosition)
                .getName());
        holder.mDetail = (TextView) convertView.findViewById(R.id.item_detail);
        holder.mDetail.setText(getChild(groupPosition, childPosition)
                .getDetail());
        return convertView;
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        /* 很重要：实现ChildView点击事件，必须返回true */
        return true;
    }

    private Drawable getRoundCornerDrawable(int resId, float roundPX /* 圆角的半径 */) {
        Drawable drawable = mContext.getResources().getDrawable(resId);
        int w = mContext.getResources().getDimensionPixelSize(R.dimen.image_width);
        int h = w;

        Bitmap bitmap = Bitmap
                .createBitmap(w,h,
                        drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                                : Bitmap.Config.RGB_565);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        drawable.draw(canvas);

        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        Bitmap retBmp = Bitmap.createBitmap(width, height, Config.ARGB_8888);
        Canvas can = new Canvas(retBmp);

        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, width, height);
        final RectF rectF = new RectF(rect);

        paint.setColor(color);
        paint.setAntiAlias(true);
        can.drawARGB(0, 0, 0, 0);
        can.drawRoundRect(rectF, roundPX, roundPX, paint);

        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        can.drawBitmap(bitmap, rect, rect, paint);
        return new BitmapDrawable(retBmp);
    }

    private class GroupViewHolder {
        TextView mGroupName;
        TextView mGroupCount;
    }

    private class ChildViewHolder {
        ImageView mIcon;
        TextView mChildName;
        TextView mDetail;
    }

}
</span>

        里面用到的有两个布局，GroupView（ChildViewt没展开的情况）如图：  

布局group_item_layout.xml如下:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:orientation="horizontal" >

    <TextView
        android:id="@+id/group_name"
        android:layout_width="wrap_content"
        android:layout_height="?android:attr/listPreferredItemHeight"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:layout_marginLeft="35dip"
        android:gravity="center_vertical"
        android:singleLine="true" />

    <TextView
        android:id="@+id/group_count"
        android:layout_width="wrap_content"
        android:layout_height="?android:attr/listPreferredItemHeight"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:layout_marginLeft="5dip"
        android:gravity="center_vertical"
        android:singleLine="true"/>

</LinearLayout>

         另外一个就是ChildView，本例仿QQ好友列表，如图：

哈哈，熟悉吧。布局child_item_layout.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="wrap_content"
    android:minHeight="@dimen/min_Height"
    <span style="color:#ff0000;">android:descendantFocusability="blocksDescendants"
</span>    android:orientation="horizontal" >

    <ImageView
        android:id="@+id/img"
        android:layout_width="@dimen/image_width"
        android:layout_height="@dimen/image_width"
        android:layout_marginLeft="2dip"
        android:layout_marginRight="10dip"
        android:layout_gravity="center_vertical" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/item_name"
            android:layout_width="wrap_content"
            android:layout_height="0.0dip"
            android:gravity="center_vertical"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/item_detail"
            android:layout_width="wrap_content"
            android:layout_height="0.0dip"
            android:gravity="center_vertical"
            android:singleLine="true"
            android:ellipsize="end"
            android:layout_weight="1" />

    </LinearLayout>

</LinearLayout>

        适配器弄好了，ExpandableListView就用系统的，现在只剩下显示的问题啦

        先来几张效果图：

主Activity如下：

package com.xyz.expande;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;

public class HomeActivity extends Activity implements OnChildClickListener {

    private ExpandableListView mListView = null;
    private ExpandeAdapter mAdapter = null;
    private List<List<Item>> mData = new ArrayList<List<Item>>();

    private int[] mGroupArrays = new int[] {
            R.array.tianlongbabu,
            R.array.shediaoyingxiongzhuan,
            R.array.shendiaoxialv };

    private int[] mDetailIds = new int[] {
            R.array.tianlongbabu_detail,
            R.array.shediaoyingxiongzhuan_detail,
            R.array.shendiaoxialv_detail };

    private int[][] mImageIds = new int[][] {
            { R.drawable.img_00,
              R.drawable.img_01,
              R.drawable.img_02 },
            { R.drawable.img_10,
              R.drawable.img_11,
              R.drawable.img_12,
              R.drawable.img_13,
              R.drawable.img_14,
              R.drawable.img_15,
              R.drawable.img_16 },
            { R.drawable.img_20,
              R.drawable.img_21 } };

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        initData();
        mListView = new ExpandableListView(this);
        mListView.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
                LayoutParams.FILL_PARENT));
        setContentView(mListView);

        mListView.setGroupIndicator(getResources().getDrawable(
                R.drawable.expander_floder));
        mAdapter = new ExpandeAdapter(this, mData);
        mListView.setAdapter(mAdapter);
        mListView.setOnChildClickListener(this);
    }

    <span style="color:#ff0000;">/*
     * ChildView 设置 布局很可能onChildClick进不来，要在 ChildView layout 里加上
     * android:descendantFocusability="blocksDescendants",
     * 还有isChildSelectable里返回true
     */
</span>    @Override
    public boolean onChildClick(ExpandableListView parent, View v,
            int groupPosition, int childPosition, long id) {
        // TODO Auto-generated method stub
        Item item = mAdapter.getChild(groupPosition, childPosition);
        new AlertDialog.Builder(this)
                .setTitle(item.getName())
                .setMessage(item.getDetail())
                .setIcon(android.R.drawable.ic_menu_more)
                .setNegativeButton(android.R.string.cancel,
                        new OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int which) {
                                // TODO Auto-generated method stub

                            }
                        }).create().show();
        return true;
    }

    private void initData() {
        for (int i = 0; i < mGroupArrays.length; i++) {
            List<Item> list = new ArrayList<Item>();
            String[] childs = getStringArray(mGroupArrays[i]);
            String[] details = getStringArray(mDetailIds[i]);
            for (int j = 0; j < childs.length; j++) {
                Item item = new Item(mImageIds[i][j], childs[j], details[j]);
                list.add(item);
            }
            mData.add(list);
        }
    }

    private String[] getStringArray(int resId) {
        return getResources().getStringArray(resId);
    }

}

        写这个demo的时候，想实现ChildView的点击事件，实现接口onChildClick，发现不进来，很尴尬。。。最后还是在网上找到答案了，第一，在适配器里isChildSelectable 必须返回true，第二，ChildView布局child_item_layout.xml最外层的layout设置个属性：

<span style="FONT-SIZE: 14px"><span xmlns="http://www.w3.org/1999/xhtml"><span xmlns="http://www.w3.org/1999/xhtml"><span xmlns="http://www.w3.org/1999/xhtml"><span xmlns="http://www.w3.org/1999/xhtml">android:descendantFocusability="blocksDescendants"</span></span></span></span></span>

上面已标示红色的啦。

       细心的同学会发现 Item 是啥？也贴出来吧

package com.xyz.expande;

public class Item {

    private int resId;
    private String name;
    private String detail;

    public Item(int resId, String name, String detail) {
        this.resId  = resId;
        this.name   = name;
        this.detail = detail;
    }

    public void setImageId(int resId) {
        this.resId  = resId;
    }

    public int getImageId() {
        return resId;
    }

    public void setName(String name) {
        this.name   = name;
    }

    public String getName() {
        return name;
    }

    public void setDetail(String detail) {
        this.detail = detail;
    }

    public String getDetail() {
        return detail;
    }

    public String toString() {
        return "Item[" + resId + ", " + name + ", " + detail + "]";
    }

}

    。。。这不是面向对象程序设计（OOP)类及类的实现最简单的例子么。

    有不对的地方请指正，互相学习！（ChildView左边的图片处理成圆角：请看函数getRoundCornerDrawable：具体细节请看：Android --- 图片的特效处理

    免分下载源码路径：http://download.csdn.net/detail/zhouyuanjing/4843520   

    ~~完~~