Android横向ListView功能实现-优快云博客

本文介绍了一种用于App中实现横向滚动ListView的方法，适用于显示动态数量的新闻附件等场景。通过自定义HorizontalListView类并结合适配器，可以轻松创建一个可以左右滑动查看多个项目的列表。

--在开发类似新闻功能的App过程中需要在新闻页面展示新闻附件，附件一多的话一行展示不完，换行又不好看，为此需要做像今日头条导航栏那样可以横向滑动的列表，不同点在于附件数量是动态添加的可能有一个也可能是十个，所以做成ListView方式最好。下面是网上横向ListView的例子，很好用，拿来借鉴一下：

public class HorizontalListView extends AdapterView<ListAdapter> {
public boolean mAlwaysOverrideTouch = true;
protected ListAdapter mAdapter;
private int mLeftViewIndex = -1;
private int mRightViewIndex = 0;
protected int mCurrentX;
protected int mNextX;
private int mMaxX = Integer.MAX_VALUE;
private int mDisplayOffset = 0;
protected Scroller mScroller;
private GestureDetector mGesture;
private Queue<View> mRemovedViewQueue = new LinkedList<View>();
private OnItemSelectedListener mOnItemSelected;
private OnItemClickListener mOnItemClicked;
private OnItemLongClickListener mOnItemLongClicked;
private boolean mDataChanged = false;


public HorizontalListView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initView();
}

private synchronized void initView() {
    mLeftViewIndex = -1;
    mRightViewIndex = 0;
    mDisplayOffset = 0;
    mCurrentX = 0;
    mNextX = 0;
    mMaxX = Integer.MAX_VALUE;
    mScroller = new Scroller(getContext());
    mGesture = new GestureDetector(getContext(), mOnGesture);
}

@Override
public void setOnItemSelectedListener(AdapterView.OnItemSelectedListener listener) {
    mOnItemSelected = listener;
}

@Override
public void setOnItemClickListener(AdapterView.OnItemClickListener listener) {
    mOnItemClicked = listener;
}

@Override
public void setOnItemLongClickListener(AdapterView.OnItemLongClickListener listener) {
    mOnItemLongClicked = listener;
}

private DataSetObserver mDataObserver = new DataSetObserver() {

    @Override
    public void onChanged() {
        synchronized (HorizontalListView.this) {
            mDataChanged = true;
        }
        invalidate();
        requestLayout();
    }

    @Override
    public void onInvalidated() {
        reset();
        invalidate();
        requestLayout();
    }

};

@Override
public ListAdapter getAdapter() {
    return mAdapter;
}

@Override
public View getSelectedView() {
    //TODO: implement
    return null;
}

@Override
public void setAdapter(ListAdapter adapter) {
    if (mAdapter != null) {
        mAdapter.unregisterDataSetObserver(mDataObserver);
    }
    mAdapter = adapter;
    mAdapter.registerDataSetObserver(mDataObserver);
    reset();
}

private synchronized void reset() {
    initView();
    removeAllViewsInLayout();
    requestLayout();
}

@Override
public void setSelection(int position) {
    //TODO: implement
}

private void addAndMeasureChild(final View child, int viewPos) {
    LayoutParams params = child.getLayoutParams();
    if (params == null) {
        params = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
    }

    addViewInLayout(child, viewPos, params, true);
    child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
            MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));
}


@Override
protected synchronized void onLayout(boolean changed, int left, int top, int right, int bottom) {
    super.onLayout(changed, left, top, right, bottom);

    if (mAdapter == null) {
        return;
    }

    if (mDataChanged) {
        int oldCurrentX = mCurrentX;
        initView();
        removeAllViewsInLayout();
        mNextX = oldCurrentX;
        mDataChanged = false;
    }

    if (mScroller.computeScrollOffset()) {
        int scrollx = mScroller.getCurrX();
        mNextX = scrollx;
    }

    if (mNextX <= 0) {
        mNextX = 0;
        mScroller.forceFinished(true);
    }
    if (mNextX >= mMaxX) {
        mNextX = mMaxX;
        mScroller.forceFinished(true);
    }

    int dx = mCurrentX - mNextX;

    removeNonVisibleItems(dx);
    fillList(dx);
    positionItems(dx);

    mCurrentX = mNextX;

    if (!mScroller.isFinished()) {
        post(new Runnable() {
            @Override
            public void run() {
                requestLayout();
            }
        });

    }
}

private void fillList(final int dx) {
    int edge = 0;
    View child = getChildAt(getChildCount() - 1);
    if (child != null) {
        edge = child.getRight();
    }
    fillListRight(edge, dx);

    edge = 0;
    child = getChildAt(0);
    if (child != null) {
        edge = child.getLeft();
    }
    fillListLeft(edge, dx);


}

private void fillListRight(int rightEdge, final int dx) {
    while (rightEdge + dx < getWidth() && mRightViewIndex < mAdapter.getCount()) {

        View child = mAdapter.getView(mRightViewIndex, mRemovedViewQueue.poll(), this);
        addAndMeasureChild(child, -1);
        rightEdge += child.getMeasuredWidth();

        if (mRightViewIndex == mAdapter.getCount() - 1) {
            mMaxX = mCurrentX + rightEdge - getWidth();
        }

        if (mMaxX < 0) {
            mMaxX = 0;
        }
        mRightViewIndex++;
    }

}

private void fillListLeft(int leftEdge, final int dx) {
    while (leftEdge + dx > 0 && mLeftViewIndex >= 0) {
        View child = mAdapter.getView(mLeftViewIndex, mRemovedViewQueue.poll(), this);
        addAndMeasureChild(child, 0);
        leftEdge -= child.getMeasuredWidth();
        mLeftViewIndex--;
        mDisplayOffset -= child.getMeasuredWidth();
    }
}

private void removeNonVisibleItems(final int dx) {
    View child = getChildAt(0);
    while (child != null && child.getRight() + dx <= 0) {
        mDisplayOffset += child.getMeasuredWidth();
        mRemovedViewQueue.offer(child);
        removeViewInLayout(child);
        mLeftViewIndex++;
        child = getChildAt(0);

    }

    child = getChildAt(getChildCount() - 1);
    while (child != null && child.getLeft() + dx >= getWidth()) {
        mRemovedViewQueue.offer(child);
        removeViewInLayout(child);
        mRightViewIndex--;
        child = getChildAt(getChildCount() - 1);
    }
}

private void positionItems(final int dx) {
    if (getChildCount() > 0) {
        mDisplayOffset += dx;
        int left = mDisplayOffset;
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            int childWidth = child.getMeasuredWidth();
            child.layout(left, 0, left + childWidth, child.getMeasuredHeight());
            left += childWidth + child.getPaddingRight();
        }
    }
}

public synchronized void scrollTo(int x) {
    mScroller.startScroll(mNextX, 0, x - mNextX, 0);
    requestLayout();
}

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    boolean handled = super.dispatchTouchEvent(ev);
    handled |= mGesture.onTouchEvent(ev);
    return handled;
}

protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                          float velocityY) {
    synchronized (HorizontalListView.this) {
        mScroller.fling(mNextX, 0, (int) -velocityX, 0, 0, mMaxX, 0, 0);
    }
    requestLayout();

    return true;
}

protected boolean onDown(MotionEvent e) {
    mScroller.forceFinished(true);
    return true;
}

private OnGestureListener mOnGesture = new GestureDetector.SimpleOnGestureListener() {

    @Override
    public boolean onDown(MotionEvent e) {
        return HorizontalListView.this.onDown(e);
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                           float velocityY) {
        return HorizontalListView.this.onFling(e1, e2, velocityX, velocityY);
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2,
                            float distanceX, float distanceY) {

        synchronized (HorizontalListView.this) {
            mNextX += (int) distanceX;
        }
        requestLayout();

        return true;
    }

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            if (isEventWithinView(e, child)) {
                if (mOnItemClicked != null) {
                    mOnItemClicked.onItemClick(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i));
                }
                if (mOnItemSelected != null) {
                    mOnItemSelected.onItemSelected(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i));
                }
                break;
            }

        }
        return true;
    }

    @Override
    public void onLongPress(MotionEvent e) {
        int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = getChildAt(i);
            if (isEventWithinView(e, child)) {
                if (mOnItemLongClicked != null) {
                    mOnItemLongClicked.onItemLongClick(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i));
                }
                break;
            }

        }
    }

    private boolean isEventWithinView(MotionEvent e, View child) {
        Rect viewRect = new Rect();
        int[] childPosition = new int[2];
        child.getLocationOnScreen(childPosition);
        int left = childPosition[0];
        int right = left + child.getWidth();
        int top = childPosition[1];
        int bottom = top + child.getHeight();
        viewRect.set(left, top, right, bottom);
        return viewRect.contains((int) e.getRawX(), (int) e.getRawY());
    }
};
}
复制代码

--界面引用如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#dddd"
android:gravity="center_horizontal"
android:orientation="vertical">

<com.hundsun.gildata.downloadpdf.HorizontalListView
    android:id="@+id/list"
    android:layout_width="match_parent"
    android:layout_height="40dp"/>
</LinearLayout>
复制代码

--适配器

public class HorizontalListViewAdapter extends BaseAdapter {
List<String> mData;
Context mContext;
public HorizontalListViewAdapter(Context mContext, List<String> mData) {
    this.mData = mData;
    this.mContext=mContext;
}

@Override
public int getCount() {
    return mData.size();
}

@Override
public Object getItem(int position) {
    return position;
}

private ViewHolder vh = new ViewHolder();

private static class ViewHolder {
    private TextView file;
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if (convertView == null) {
        convertView = LayoutInflater.from(mContext).inflate(R.layout.hor_list_item, null);
        vh.file = (TextView) convertView.findViewById(R.id.file);
        convertView.setTag(vh);
    } else {
        vh = (ViewHolder) convertView.getTag();
    }
    return convertView;
}
}
复制代码

--适配器很简单，只需要一个TextView就行了,自定义是为了给他添加附件类型图标。适配器用到的hor_list_item.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="match_parent"
          android:background="@xml/attch"
          android:gravity="center"
          android:layout_margin="4dp"
          android:orientation="horizontal"
          android:padding="4dp">

<TextView
    android:id="@+id/file"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:drawableLeft="@drawable/file"
    android:drawableStart="@drawable/file"
    android:gravity="center"
    android:focusable="false"
    android:padding="4dp"
    android:text="附件"
    android:textColor="#6f6f6f"/>

</LinearLayout>
复制代码

--在MainActivity中可以这么用：

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
HorizontalListView mHorizontalListView;
HorizontalListViewAdapter mAdapter;
List<String> mData;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mHorizontalListView = (HorizontalListView) findViewById(R.id.list);
    initView();
}
private void initView() {
    mData = new ArrayList<>();
    mData.add("504540");
    mData.add("457662");
    mData.add("502690");
    mData.add("457669");
    mData.add("457672");
    mData.add("481660");
    mData.add("479358");
    mAdapter = new HorizontalListViewAdapter(this, mData);
    mHorizontalListView.setAdapter(mAdapter);

    mHorizontalListView.setOnItemClickListener(this);
    mWifiManager = (WifiManager) this
            .getSystemService(Context.WIFI_SERVICE);
    WifiInfo wifiInfo = mWifiManager.getConnectionInfo();
    editPort.setText(int2ip(wifiInfo.getIpAddress()) + ":55555");
}
@Override
public void onItemClick(AdapterView<?> view, View view1, final int i, long l) {
    Toast.makeText(this, "id=" + mData.get(i), Toast.LENGTH_SHORT).show();
}
}
复制代码