Android ExpandableListView BaseExpandableListAdapter (类似QQ分组列表）

分组列表视图(ExpandableListView)

和ListView不同的是它是一个两级的滚动列表视图,每一个组可以展开,显示一些子项,类似于
QQ列表,这些项目来至于ExpandableListAdapter的子类,也就是说,要实现向里面添加项目,必
须写一个子类实现ExpandableListAdapter的接口或者使用系统为我们实现在子类

　　常用属性　　　

　　　　1. android:childDivider 指定各组内子类表项之间的分隔条,

　　　　2. android:childIndicator 显示在子列表旁边的Drawable对象

　　　　3. android:childIndicatorLeft 子列表项指示符的左边约束位置

　　　　4. android:childIndicatorRight 子列表项指示符的右边约束位置

　　　　5. android:groupIndicator 显示在组列表旁边的Drawable对象

　　　　6. android:indicatorLeft 组列表项指示器的左边约束位置

　　　　7. android:indicatorRight 组列表项指示器的右边约束位置

一般适用于ExpandableListView的Adapter都要继承BaseExpandableListAdapter这个类，
并且必须重载getGroupView和getChildView这两个最为重要的方法。
当扩展BaseExpandableListAdapter时，要实现全部方法，关键是实现其中的四个方法。

1、首相activity_main.xml布局搭建

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent">

     <ExpandableListView
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:id="@+id/elv"/>

 </RelativeLayout>

activity_main.xml

2、然后是搭建QQ分组的布局

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical" >

     <TextView
         android:id="@+id/groupName"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:textSize="20sp"
         android:text="分组名称" />

     <TextView
         android:id="@+id/groupOnline"
         android:layout_alignParentRight="true"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="0/8" />

 </RelativeLayout>

item_group.xml

3、再搭建分组中各选项的布局（QQ联系人，包括头像，昵称，签名）

　　 这里由于引用了外部的自定义的控件，所以这里包名加类名

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:layout_gravity="center_vertical"
     android:orientation="horizontal" >

     <com.test.lesson7_expandablelistview.CircleImageView
         android:id="@+id/img"
         android:layout_width="80dp"
         android:layout_height="80dp"
         android:src="@drawable/ic_launcher" />

     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginLeft="10dp"
         android:orientation="vertical" >

         <TextView
             android:id="@+id/nickName"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:text="昵称"
             android:textSize="18sp" />

         <LinearLayout
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_marginTop="10dp"
             android:orientation="horizontal" >

             <TextView
                 android:id="@+id/online"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="[在线]" />

             <TextView
                 android:id="@+id/sign"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_marginLeft="10dp"
                 android:text="我要飞的更高~" />
         </LinearLayout>
     </LinearLayout>

 </LinearLayout>

item_child.xml

4、圆角图片形状

　　在res/values中建circle_attr.xml

 <resources>

     <declare-styleable name="CircularImage">
         <attr name="border_width" format="dimension" />
         <attr name="border_color" format="color" />
     </declare-styleable>

 </resources>

5、然后新建一个CircleImageView继承ImageView

　　此处自定义控件是在GitHub上下载

 public class CircleImageView extends ImageView {
     private static final Xfermode MASK_XFERMODE;
     private Bitmap mask;
     private Paint paint;
     private int mBorderWidth = 10;
     private int mBorderColor = Color.parseColor("#f2f2f2");
     private boolean useDefaultStyle = false;

     static {
         PorterDuff.Mode localMode = PorterDuff.Mode.DST_IN;
         MASK_XFERMODE = new PorterDuffXfermode(localMode);
     }

     public CircleImageView(Context context) {
         super(context);
     }

     public CircleImageView(Context context, AttributeSet attrs) {
         this(context, attrs, 0);
     }

     public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);
         TypedArray a = context.obtainStyledAttributes(attrs,
                 R.styleable.CircularImage);
         mBorderColor = a.getColor(R.styleable.CircularImage_border_color,
                 mBorderColor);
         final int def = (int) (2 * context.getResources().getDisplayMetrics().density + 0.5f);
         mBorderWidth = a.getDimensionPixelOffset(
                 R.styleable.CircularImage_border_width, def);
         a.recycle();
     }

     private void useDefaultStyle(boolean useDefaultStyle) {
         this.useDefaultStyle = useDefaultStyle;
     }

     @Override
     protected void onDraw(Canvas canvas) {
         if (useDefaultStyle) {
             super.onDraw(canvas);
             return;
         }
         final Drawable localDraw = getDrawable();
         if (localDraw == null) {
             return;
         }
         if (localDraw instanceof NinePatchDrawable) {
             return;
         }
         if (this.paint == null) {
             final Paint localPaint = new Paint();
             localPaint.setFilterBitmap(false);
             localPaint.setAntiAlias(true);
             localPaint.setXfermode(MASK_XFERMODE);
             this.paint = localPaint;
         }
         final int width = getWidth();
         final int height = getHeight();
         int layer = canvas.saveLayer(0.0F, 0.0F, width, height, null, 31);
         localDraw.setBounds(0, 0, width, height);
         localDraw.draw(canvas);
         if ((this.mask == null) || (this.mask.isRecycled())) {
             this.mask = createOvalBitmap(width, height);
         }
         canvas.drawBitmap(this.mask, 0.0F, 0.0F, this.paint);
         canvas.restoreToCount(layer);
         drawBorder(canvas, width, height);
     }

     private void drawBorder(Canvas canvas, final int width, final int height) {
         if (mBorderWidth == 0) {
             return;
         }
         final Paint mBorderPaint = new Paint();
         mBorderPaint.setStyle(Paint.Style.STROKE);
         mBorderPaint.setAntiAlias(true);
         mBorderPaint.setColor(mBorderColor);
         mBorderPaint.setStrokeWidth(mBorderWidth);
         canvas.drawCircle(width / 2, height / 2, (width - mBorderWidth) / 2,
                 mBorderPaint);
         canvas = null;
     }

     public Bitmap createOvalBitmap(final int width, final int height) {
         Bitmap.Config localConfig = Bitmap.Config.ARGB_8888;
         Bitmap localBitmap = Bitmap.createBitmap(width, height, localConfig);
         Canvas localCanvas = new Canvas(localBitmap);
         Paint localPaint = new Paint();
         final int padding = (mBorderWidth - 3) > 0 ? mBorderWidth - 3 : 1;

         RectF localRectF = new RectF(padding, padding, width - padding, height
                 - padding);
         localCanvas.drawOval(localRectF, localPaint);

         return localBitmap;
     }

 }

CircleImageView

6、创建Group类

 public class Group {
     //分组名
     public String groupName;
     //有很多User
     public List<User> list;

     public Group(String groupName){
         this.groupName = groupName;
         list = new ArrayList<User>();
     }
     //添加User
     public void addUser(User user){
         list.add(user);
     }

     //获取某个分组中User的数量
     public int getChildCount() {
         return list.size();
     }
     //获取某个分组中User在线的数量
     public int getOnlineCount(){
         int sum = 0;
         for (User user : list) {
             if(user.isOnline()){
                 sum++;
             }
         }
         return sum;
     }
     //获取分组中某个孩子
     public User getChild(int childPosition) {
         return list.get(childPosition);
     }

 }

Group.java

7、创建User类

 public class User {
     private int imgId;
     private String nickName;
     private boolean isOnline;
     private String sign;

     public User() {
         super();
     }
     public User(int imgId, String nickName, boolean isOnline, String sign) {
         super();
         this.imgId = imgId;
         this.nickName = nickName;
         this.isOnline = isOnline;
         this.sign = sign;
     }

     public int getImgId() {
         return imgId;
     }
     public void setImgId(int imgId) {
         this.imgId = imgId;
     }
     public String getNickName() {
         return nickName;
     }
     public void setNickName(String nickName) {
         this.nickName = nickName;
     }
     public boolean isOnline() {
         return isOnline;
     }
     public void setOnline(boolean isOnline) {
         this.isOnline = isOnline;
     }
     public String getSign() {
         return sign;
     }
     public void setSign(String sign) {
         this.sign = sign;
     }

 }

User

8、设置适配器

 public class GroupAdapter extends BaseExpandableListAdapter{

     Context context;
     List<Group> list;

     public GroupAdapter(Context context, List<Group> list) {
         this.context = context;
         this.list = list;
     }

     @Override
     public View getGroupView(int groupPosition, boolean isExpanded,
             View convertView, ViewGroup parent) {
         GroupHolder holder;
         if(convertView == null){
             convertView = View.inflate(context, R.layout.item_grouplayout, null);
             holder = new GroupHolder(convertView);
             convertView.setTag(holder);
         }else{
             holder = (GroupHolder) convertView.getTag();
         }
         //设置数据
         Group group = getGroup(groupPosition);
         holder.groupName.setText(group.groupName);
         holder.groupOnline.setText(group.getOnlineCount()+"/"+getChildrenCount(groupPosition));

         return convertView;
     }

     @Override
     public View getChildView(int groupPosition, int childPosition,
             boolean isLastChild, View convertView, ViewGroup parent) {
         ChildHolder holder;
         if(convertView == null){
             convertView = View.inflate(context, R.layout.item_childlayout, null);
             holder = new ChildHolder(convertView);
             convertView.setTag(holder);
         }else{
             holder = (ChildHolder) convertView.getTag();
         }
         //设置数据
         User user = getGroup(groupPosition).getChild(childPosition);
         holder.img.setImageResource(user.getImgId());
         holder.nickName.setText(user.getNickName());
         holder.online.setText(user.isOnline()?"[在线]":"[离线]");
         holder.sign.setText(user.getSign());

         return convertView;

     }

     class GroupHolder{
         TextView groupName;
         TextView groupOnline;

         public GroupHolder(View convertView){
             groupName = (TextView) convertView.findViewById(R.id.groupName);
             groupOnline = (TextView) convertView.findViewById(R.id.groupOnline);

         }
     }
     class ChildHolder{
         ImageView img;
         TextView nickName;
         TextView online;
         TextView sign;

         public ChildHolder(View convertView){
             img = (ImageView) convertView.findViewById(R.id.img);
             nickName = (TextView) convertView.findViewById(R.id.nickName);
             online = (TextView) convertView.findViewById(R.id.online);
             sign = (TextView) convertView.findViewById(R.id.sign);

         }

     }

     @Override
     public int getGroupCount() {
         return list.size();
     }

     @Override
     public int getChildrenCount(int groupPosition) {
         return list.get(groupPosition).getChildCount();
     }

     @Override
     public Group getGroup(int groupPosition) {
         return list.get(groupPosition);
     }

     @Override
     public User getChild(int groupPosition, int childPosition) {
         return list.get(groupPosition).getChild(childPosition);
     }

     @Override
     public long getGroupId(int groupPosition) {
         return groupPosition;
     }

     @Override
     public long getChildId(int groupPosition, int childPosition) {
         return childPosition;
     }

     @Override
     public boolean hasStableIds() {
         return true;
     }

     @Override
     public boolean isChildSelectable(int groupPosition, int childPosition) {
         return true;
     }

 }

GroupAdapter

9、MainActivity.java中将所有组件找到，初始化数据源，并给ListView设置适配器

 public class MainActivity extends Activity {

     ExpandableListView elv;
     private List<Group> list = new ArrayList<Group>();
     int[] img = new int[6];

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         initData();
         elv = (ExpandableListView) findViewById(R.id.elv);
         GroupAdapter adapter = new GroupAdapter(getBaseContext(), list);
         elv.setAdapter(adapter);

     }

     private void initData() {
         for (int i = 0; i < img.length; i++) {
             try {
                 img[i] = R.drawable.class.getField("img0"+(i+1)).getInt(null);
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }

         Group group1 = new Group("贵圈好乱");
         group1.addUser(new User(img[0], "张翰", true, "我爱娜扎！"));
         group1.addUser(new User(img[1], "郑爽", false, "妈蛋，要么瘦，要么死！"));
         group1.addUser(new User(img[2], "胡彦斌", true, "其实我只是长得抽象了"));
         group1.addUser(new User(img[5], "撒贝宁", true, "子怡当年没选择我是个美丽的错误"));
         group1.addUser(new User(img[3], "杨幂", false, "其实我跟恺威已经离婚了，现在跟李易峰在一起，就酱~"));

         Group group2 = new Group("超星星");
         group2.addUser(new User(img[4], "林志炫", true, "其实我的小肚子都是唱歌导致的，哈哈哈"));

         list.add(group1);
         list.add(group2);

     }

 }

MainActivity.java

运行效果有点渣渣。请忽略：