本文内容：
1、横向ListView的所有实现思路;
2、其中一个最通用的思路HorizontalListView，并基于横向ListView开发一个简单的相册；
3、实现的横向ListView在点击、浏览时item背景会变色，并解决了listview里setSelected造成item的选择状态混乱的问题。
众所周知，ListView默认的方向是垂直的，但有些时候人们更喜欢横向ListView。纵观整个网络，横向ListView的实现思路如下:
1、在布局里用HorizontalScrollView包含一个ListView，参考这里;
2、利用GridView，把它的行数设为1行；
3、有人继承ListView构造了一个HorizontalScrollListView，参见：这里
4、国外一位大牛继承AdapterView<ListAdapter>构造的HorizontalListView，这是以上所有方法里本人认为最正统的方法，本文即基于此方法，参见:这里
下面看源码：
这是Activity的布局文件:activity_main.xml
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity"
>
<org.yanzi.ui.HorizontalListView
android:id="@+id/horizon_listview"
android:layout_width="match_parent"
android:layout_height="150dip"
android:layout_alignParentTop="true"
>
</org.yanzi.ui.HorizontalListView>
<ImageView
android:id="@+id/image_preview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/horizon_listview"
android:layout_centerInParent="true"
android:clickable="true"
android:background="@drawable/selector_imageview_background"
/>
<!-- android:background="@android:drawable/ic_menu_gallery" -->
</RelativeLayout>
这是横向listview的每个item的布局，图片+文字，horizontal_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="2dip"
android:paddingRight="2dip"
android:paddingTop="2dip"
android:paddingBottom="2dip"
android:orientation="vertical"
android:gravity="center"
android:clickable="true"
android:background="@drawable/selector_item_background">
<ImageView
android:id="@+id/img_list_item"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:id="@+id/text_list_item"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"/>
</LinearLayout>
下面文件是selector_imageview_background.xml，这是大图片你点击浏览时背景发生变化的selector，没有啥实际作用。
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@android:color/holo_green_light" android:state_pressed="true"/>
<item android:drawable="@android:color/holo_green_light" android:state_focused="true"/>
<item android:drawable="@drawable/image_background"></item>
<!-- android:drawable="@android:color/transparent" -->
</selector>
下面是每个item的selector，在focus和select时颜色会发生变化:selector_item_background.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@android:color/holo_red_light" android:state_selected="true"/>
<item android:drawable="@android:color/holo_green_dark" android:state_pressed="true"/>
<item android:drawable="@android:color/transparent"/>
</selector>
主程序:MainActivity.java
package org.yanzi.testhorizontallistview;
import org.yanzi.ui.HorizontalListView;
import org.yanzi.ui.HorizontalListViewAdapter;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ImageView;
public class MainActivity extends Activity {
HorizontalListView hListView;
HorizontalListViewAdapter hListViewAdapter;
ImageView previewImg;
View olderSelectView = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initUI();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void initUI(){
hListView = (HorizontalListView)findViewById(R.id.horizon_listview);
previewImg = (ImageView)findViewById(R.id.image_preview);
String[] titles = {"怀师", "南怀瑾军校", "闭关", "南怀瑾", "南公庄严照", "怀师法相"};
final int[] ids = {R.drawable.nanhuaijin_miss, R.drawable.nanhuaijin_school,
R.drawable.nanhuaijin_biguan, R.drawable.nanhuaijin,
R.drawable.nanhuaijin_zhuangyan, R.drawable.nanhuaijin_faxiang};
hListViewAdapter = new HorizontalListViewAdapter(getApplicationContext(),titles,ids);
hListView.setAdapter(hListViewAdapter);
// hListView.setOnItemSelectedListener(new OnItemSelectedListener() {
//
// @Override
// public void onItemSelected(AdapterView<?> parent, View view,
// int position, long id) {
// // TODO Auto-generated method stub
// if(olderSelected != null){
// olderSelected.setSelected(false); //上一个选中的View恢复原背景
// }
// olderSelected = view;
// view.setSelected(true);
// }
//
// @Override
// public void onNothingSelected(AdapterView<?> parent) {
// // TODO Auto-generated method stub
//
// }
// });
hListView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// TODO Auto-generated method stub
// if(olderSelectView == null){
// olderSelectView = view;
// }else{
// olderSelectView.setSelected(false);
// olderSelectView = null;
// }
// olderSelectView = view;
// view.setSelected(true);
previewImg.setImageResource(ids[position]);
hListViewAdapter.setSelectIndex(position);
hListViewAdapter.notifyDataSetChanged();
}
});
}
}
HorizontalListView.java 这就是自定义的横向listview
package org.yanzi.ui;
/*
* HorizontalListView.java v1.5
*
*
* The MIT License
* Copyright (c) 2011 Paul Soucy (paul@dev-smart.com)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
*/
import java.util.LinkedList;
import java.util.Queue;
import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.Scroller;
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());
}
};
}
HorizontalListViewAdapter.java 横向listview的适配器，我将他单独写到一个java文件里。
package org.yanzi.ui;
import org.yanzi.testhorizontallistview.R;
import org.yanzi.util.BitmapUtil;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.drawable.Drawable;
import android.media.ThumbnailUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class HorizontalListViewAdapter extends BaseAdapter{
private int[] mIconIDs;
private String[] mTitles;
private Context mContext;
private LayoutInflater mInflater;
Bitmap iconBitmap;
private int selectIndex = -1;
public HorizontalListViewAdapter(Context context, String[] titles, int[] ids){
this.mContext = context;
this.mIconIDs = ids;
this.mTitles = titles;
mInflater=(LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);//LayoutInflater.from(mContext);
}
@Override
public int getCount() {
return mIconIDs.length;
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if(convertView==null){
holder = new ViewHolder();
convertView = mInflater.inflate(R.layout.horizontal_list_item, null);
holder.mImage=(ImageView)convertView.findViewById(R.id.img_list_item);
holder.mTitle=(TextView)convertView.findViewById(R.id.text_list_item);
convertView.setTag(holder);
}else{
holder=(ViewHolder)convertView.getTag();
}
if(position == selectIndex){
convertView.setSelected(true);
}else{
convertView.setSelected(false);
}
holder.mTitle.setText(mTitles[position]);
iconBitmap = getPropThumnail(mIconIDs[position]);
holder.mImage.setImageBitmap(iconBitmap);
return convertView;
}
private static class ViewHolder {
private TextView mTitle ;
private ImageView mImage;
}
private Bitmap getPropThumnail(int id){
Drawable d = mContext.getResources().getDrawable(id);
Bitmap b = BitmapUtil.drawableToBitmap(d);
// Bitmap bb = BitmapUtil.getRoundedCornerBitmap(b, 100);
int w = mContext.getResources().getDimensionPixelOffset(R.dimen.thumnail_default_width);
int h = mContext.getResources().getDimensionPixelSize(R.dimen.thumnail_default_height);
Bitmap thumBitmap = ThumbnailUtils.extractThumbnail(b, w, h);
return thumBitmap;
}
public void setSelectIndex(int i){
selectIndex = i;
}
}
下面是效果图：
下图是一个item被选定后，另一个item获得了焦点:
下面是横向时的截图:
要点如下:
1、可以说这个HorizontalListView是完美的，但美中不足的并不是其他人说的不能点击、晃动、加载不全的问题，而是这个横向Listview的高度，如果你设成wrap_cotent那么将会占据整个屏幕，即使你将它适配器里的view的高度限制死，限制成很小，这个HorizontalListView的高度依然是全屏。本文代码里，我把图片缩略图弄成100dip，所以把这个HorizontalListView的高度设为了150dip。
2、在适配器里，我填充了一个图片，下面是文字。为了能让浏览图片时item有反应，搞了一个selector，它的用法详见这里. 但一开始在点击时完全没有反应，参考这里：
http://blog.csdn.net/ljz2009y/article/details/18820071 为此我的selector如下：
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@android:color/holo_red_light" android:state_selected="true"/>
<item android:drawable="@android:color/holo_green_dark" android:state_pressed="true"/>
<item android:drawable="@android:color/transparent"/>
</selector>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@android:color/holo_red_light" android:state_selected="true"/>
<item android:drawable="@android:color/holo_green_dark" android:state_pressed="true"/>
<item android:drawable="@android:color/transparent"/>
</selector>
将自然状态下的背景放到了最后，但点击浏览时依然没有作用。其实最根本原因是在布局文件里horizontal_list_item.xml要让这个布局能够clickable，即：android:clickable="true"
3、上一步完成了，还需要点击即select一个item时，让它变色并且保持住，然后点击另外一个item时，让之前得item恢复默认背景。为了实现这个问题，我曾作如下尝试：
// if(olderSelectView == null){
// olderSelectView = view;
// }else{
// olderSelectView.setSelected(false);
// olderSelectView = null;
// }
// olderSelectView = view;
// view.setSelected(true);
即在click监听里，保存上一个选中的view。遗憾的是这种方法会造成item的选中状态造成混乱，比如第一个item选中了，同时第5个item也莫名其妙的被选中了。上述情况发生在滑动时，即一屏显示不完的情况下。当我横屏时，在所有的item都能一次性显示出来情况下，用上述方法么问题。后来我想到，这可以是适配器里的缓存机制造成的，最好不要再listview适配器外对item作修改，即便修改则一定要调适配器的: hListViewAdapter.notifyDataSetChanged();通知刷新view，毕竟适配器才是view的提供者。参考这位大大的文章:http://longyi-java.iteye.com/blog/976067 在适配器里加了一个接口保存选中的索引，然后再getView函数里进行判断。如果是选中的item，则将布局设为选中状态即可，horizontal_list_item.xml里的Linearlayout就会自动加载那个selector了。而无需像这个参考链接里对每个item的元素分别设置状态。
4、BitmapUtil是个工具类，负责将id转成一个bitmap，然后用android自带的ThumbnailUtils去提取缩略图。
5、之所以horizontal_list_item布局里要设置padding是为了选中item时，整个item有种被圈住的感觉，而不是光下面一点变色。
---------------------------------本文系原创，转载请注明作者:yanzi1225627
源码下载:
Android UI开发: 横向ListView(HorizontalListView)及一个简单相册的完整实现 (附源码下载),布布扣,bubuko.com
Android UI开发: 横向ListView(HorizontalListView)及一个简单相册的完整实现 (附源码下载)