android 浮動的View不會跟隨ScrollView消失而消失，androidscrollview

android 浮動的View不會跟隨ScrollView消失而消失，androidscrollview
轉載請註明出處王亟亟的大牛之路

標題比較抽象，先上下以及項目結構

向上滑（沒到底）

滑到頭

反過來就是這個流程再反一反。

如何?？看下你就懂了

黑色的線是我們的螢幕
藍色的線類比的是我們上部的一個布局，我們現在使這個死庫水的妹子
紅色的線類比的是我們的那一個打麥麥屁股的一個LinearLayout
那麼綠色呢？
綠色其實跟紅色的內容是一模一樣只是在初始化的時候受否可見為gone，說到這裡大家理解了嗎？
我們監聽ScrollView的滑動當向上滑動的距離大於妹子時，我們的綠色部分就顯現出來，反之則隱藏。就是這麼簡單，那我們來看下代碼

自訂的滾動布局CustomScrollView

public class CustomScrollView extends ScrollView {    View mTopView;    View mFlowView;    public CustomScrollView(Context context, AttributeSet attrs) {        super(context, attrs);        // TODO Auto-generated constructor stub    }    @Override    protected void onScrollChanged(int l, int t, int oldl, int oldt) {        super.onScrollChanged(l, t, oldl, oldt);        if(mTopView != null && mFlowView != null) {            if(t >= mTopView.getHeight()) {                mFlowView.setVisibility(View.VISIBLE);            } else {                mFlowView.setVisibility(View.GONE);            }        }    }    /**     * 監聽浮動view的滾動狀態     * @param topView 頂部地區view，即當ScrollView滑動的高度要大於等於哪個view的時候隱藏floatview     * @param flowView 浮動view，即要哪個view停留在頂部     */    public void listenerFlowViewScrollState(View topView, View flowView) {        mTopView = topView;        mFlowView = flowView;    }}

主視圖MainActivity

public class MainActivity extends Activity {    private CustomScrollView mScrollView;    private ImageView mImageView;    private LinearLayout mFlowLayout;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();    }    private void initView() {        mScrollView = (CustomScrollView) findViewById(R.id.scroll_view);        mImageView = (ImageView) findViewById(R.id.image_view);        mFlowLayout = (LinearLayout) findViewById(R.id.flow_llay);        ListView listview = (ListView) findViewById(R.id.list_view);        listview.setAdapter(new ListViewDataAdapter(getData(), this));        listview.setFocusable(false);        listview.setOnItemClickListener(onItemClickListener);        setListViewHeightBasedOnChildren(listview);        //監聽浮動view的滾動狀態        mScrollView.listenerFlowViewScrollState(mImageView, mFlowLayout);        //將ScrollView滾動到起始位置        mScrollView.scrollTo(0, 0);    }    OnItemClickListener onItemClickListener = new OnItemClickListener() {        @Override        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,                long arg3) {            Toast.makeText(MainActivity.this, "菜單"+(arg2+1), Toast.LENGTH_SHORT).show();        }    };    private ArrayList<String> getData() {        ArrayList<String> data = new ArrayList<String>();        for(int i=1; i<30; i++) {            data.add("菜單"+i);        }        return data;    }    /**     * 用於解決ScrollView嵌套listview時，出現listview只能顯示一行的問題     * @param listView     */     public void setListViewHeightBasedOnChildren(ListView listView) {            // 擷取ListView對應的Adapter            ListAdapter listAdapter = listView.getAdapter();            if (listAdapter == null) {               return;            }            int totalHeight = 0;            for (int i = 0, len = listAdapter.getCount(); i < len; i++) {                // listAdapter.getCount()返回資料項目的數目                View listItem = listAdapter.getView(i, null, listView);               // 計運算元項View 的寬高                listItem.measure(0, 0);                 // 統計所有子項的總高度                    totalHeight += listItem.getMeasuredHeight();            }            ViewGroup.LayoutParams params = listView.getLayoutParams();            params.height = totalHeight+ (listView.getDividerHeight() * (listAdapter.getCount() - 1));            // listView.getDividerHeight()擷取子項間分隔字元佔用的高度            // params.height最後得到整個ListView完整顯示需要的高度            listView.setLayoutParams(params);       }  }

主布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".MainActivity" >    <com.jimstin.topfloatdemo.view.CustomScrollView        android:id="@+id/scroll_view"        android:layout_width="match_parent"        android:layout_height="match_parent">        <LinearLayout             android:layout_width="match_parent"            android:layout_height="wrap_content"            android:orientation="vertical">            <ImageView                 android:id="@+id/image_view"                android:layout_width="match_parent"                android:layout_height="120dp"                android:background="@drawable/pic01"/>           <LinearLayout                 android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:background="#4169E1">                <TextView                     android:layout_width="0dp"                    android:layout_height="wrap_content"                    android:layout_weight="1"                    android:textSize="10pt"                    android:text="打屁股麥麥"                    android:textColor="#ffffff"/>                <Button                     android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="打他屁股"                    android:textColor="#ffffff"/>            </LinearLayout>            <ListView                 android:id="@+id/list_view"                android:layout_width="match_parent"                android:layout_height="0dp"                android:layout_weight="1">            </ListView>        </LinearLayout>    </com.jimstin.topfloatdemo.view.CustomScrollView>    <LinearLayout          android:id="@+id/flow_llay"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:orientation="horizontal"         android:background="#4169E1"         android:visibility="gone">         <TextView               android:layout_width="0dp"              android:layout_height="wrap_content"              android:layout_weight="1"              android:textSize="10pt"              android:text="打屁股麥麥"              android:textColor="#ffffff"/>          <Button               android:layout_width="wrap_content"              android:layout_height="wrap_content"              android:text="打他屁股"              android:textColor="#ffffff"/>     </LinearLayout></RelativeLayout>

適配器ListViewDataAdapter

public class ListViewDataAdapter extends BaseAdapter {    private ArrayList<String> mData = new ArrayList<String>();    private Context mContext;    public ListViewDataAdapter(ArrayList<String> mData, Context mContext) {        super();        this.mData = mData;        this.mContext = mContext;    }    @Override    public int getCount() {        // TODO Auto-generated method stub        return mData.size();    }    @Override    public Object getItem(int arg0) {        // TODO Auto-generated method stub        return mData.get(arg0);    }    @Override    public long getItemId(int arg0) {        // TODO Auto-generated method stub        return 0;    }    @Override    public View getView(int arg0, View convertView, ViewGroup arg2) {        // TODO Auto-generated method stub        Holder holder = null;        if(convertView == null) {            LayoutInflater inflater = LayoutInflater.from(mContext);            convertView = inflater.inflate(R.layout.layout_list_view_item, null);            holder = new Holder();            holder.avator_iv = (ImageView) convertView.findViewById(R.id.avator);            holder.name_tv = (TextView) convertView.findViewById(R.id.item_tv);            convertView.setTag(holder);        }        holder = (Holder) convertView.getTag();        holder.avator_iv.setImageResource(R.drawable.pic02);        holder.name_tv.setText(mData.get(arg0));        return convertView;    }    class Holder {        ImageView avator_iv;        TextView name_tv;    }}

東西就這麼點，只要想到怎麼做的話實現其實並不複雜，源碼今天就不傳了，因為並沒有什麼資源檔什麼的，這幾個類 複製黏貼就能用了，周末愉快

部分內容參考互連網，如有重複請見諒

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