Android简单实现无限滚动自动滚动的ViewPager
作者：Burnner
这篇文章主要介绍了Android简单实现无限滚动自动滚动的ViewPager，百度谷歌上面也有很多关于这方面的教程，但是感觉都略显麻烦，而且封装的都不是很彻底。所以试着封装一个比较好用的ViewPager，实现思路一起通过本文学习吧
经常我们会在应用中看到一个可以自动滚动，并且无限滚动的一个ViewPager，百度谷歌上面也有很多关于这方面的教程，但是感觉都略显麻烦，而且封装的都不是很彻底。所以试着封装一个比较好用的ViewPager
效果如下：
简单的说一下实现思路，要实现无限滚动的话就要在PagerAdapter上面做一些手脚，在PagerAdapter的getCount的函数的返回值设置成Integer.MXA_VALUE就可以实现向右无限滚动，但是要实现向左无限滚动呢？就是一开始的时候setCurrentItem的时候设置一个非常大的值（大到你向左滚动了一万年还是有东西）
@Override
public int getCount() {
return Integer.MAX_VALUE;
}
mPager.setCurrentItem(10000 * mDatas.size());//一开始设置成这样的话就可以向左无限滚动了
然后另外一个就是底部的游标了：
底部的游标是用一个自定义视图：无非就是画一个背景，然后在画一个高亮的游标
/**
* 指示游标
*/
private class TipView extends View {
private int mPadding;
private int mCount;
private int mCurPos;
private Paint mNorPaint;//未被选中的颜色
private Paint mSelPaint;//被选中的颜色 白色
private int mHeight;
public TipView(Context context, int count) {
super(context);
mNorPaint = new Paint();
mNorPaint.setAntiAlias(true);
int selHeight = ShowUtils.dip2px(2);
int norHeight = ShowUtils.dip2px(1);
mHeight = ShowUtils.dip2px(2);
mNorPaint.setStrokeWidth(norHeight);
mNorPaint.setColor(Color.argb(80, 255, 255, 255));
mSelPaint = new Paint();
mSelPaint.setAntiAlias(true);
mSelPaint.setStrokeWidth(selHeight);
mSelPaint.setColor(Color.WHITE);
mCount = count;
mPadding = ShowUtils.dip2px(0);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int ow = (getWidth()-2 * mPadding)/ mCount;
int y = getHeight() / 2;
canvas.drawLine(mPadding, y, mCurPos * ow + mPadding, y, mNorPaint);
canvas.drawLine(mCurPos * ow + mPadding, y, (mCurPos + 1) * ow + mPadding, y, mSelPaint);
canvas.drawLine((mCurPos + 1) * ow + mPadding, y, getWidth() - mPadding, y, mNorPaint);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
ViewGroup.LayoutParams vp = getLayoutParams();
vp.width = ViewGroup.LayoutParams.MATCH_PARENT;
vp.height = mHeight;
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
public void setCurPostion(int pos) {
mCurPos = pos;
invalidate();
}
public void setCount(int count) {
mCount = count;
}
}
R.layout.layout_recommend_item的布局：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/iv_pic"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:contentDescription="@null"
android:scaleType="fitXY"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="48dp"
android:orientation="vertical"
android:layout_alignParentBottom="true"
android:background="@drawable/recommend"
android:gravity="center">
<TextView
android:id="@+id/tv_desc"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="@color/white"
android:textSize="@dimen/text_normal"
android:maxLines="1"
android:ellipsize="end"
android:shadowColor="#ff333333"
android:shadowDx="2"
android:shadowDy="2"
android:paddingRight="8dp"
android:paddingLeft="8dp"
android:shadowRadius="1" />
</LinearLayout>
</RelativeLayout>
还有一个是实现自动滚动，自动滚动的话就是监听OnPagerChangeListener里面的函数，在ViewPager状态改变的时候利用Handler发送一个切换界面的消息：
@Override
public void onPageScrollStateChanged(int i) {
curState = i;
if(i == ViewPager.SCROLL_STATE_DRAGGING){ //viewpager正在被拖动的时候
stopAnimation();
}else { //没有可执行消息时候添加消息 实现自动滚动
if(!(sHandler.hasMessages(START_SCROLL)&&sHandler.hasMessages(SCROLL_NEXT))){
startAnimation();
}
}
}
@Override
public void onPageSelected(final int i) { //页面跳转后得到调用
sHandler.removeMessages(SCROLL_NEXT);
sHandler.removeMessages(START_SCROLL);
if(curState == ViewPager.SCROLL_STATE_DRAGGING){
return;
}
Message msg = sHandler.obtainMessage(SCROLL_NEXT);
msg.arg1 = i + 1;
msg.obj = mPager;
sHandler.sendMessageDelayed(msg, SHOW_TIME);
mTipView.setCurPostion(i % mDatas.size());
}
整体的代码：
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.papau.show.R;
import com.papau.show.entity.HeadViewEntity;
import com.papau.show.utils.ShowUtils;
import java.util.ArrayList;
import java.util.List;
public class RecommendView extends RelativeLayout implements IRecommend {
private static final int START_SCROLL = 1;
private static final int SCROLL_NEXT = 2;
private static final int SHOW_TIME = 5000;
private List<HeadViewEntity> mDatas = new ArrayList<>();
private ViewPager mPager;
private Context mContext;
private int mWidth, mHeight;
private ImageLoader mLoader;
private DisplayImageOptions mOptions;
private int mTitleHeight;
private TipView mTipView;
private static Handler sHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
int w = msg.what;
ViewPager pager = (ViewPager) msg.obj;
switch (w) {
case START_SCROLL:
pager.setCurrentItem(msg.arg1, true);
break;
case SCROLL_NEXT:
pager.setCurrentItem(msg.arg1, true);
break;
}
}
};
public RecommendView(Context context) {
super(context);
}
public RecommendView(Context context, int w, int h) {
super(context);
mContext = context;
mWidth = w;
mHeight = h;
initView();
// mPager.setAdapter(new RecommendAdapter());
mPager.setOnPageChangeListener(new MOnPagerChangeListener());
mLoader = ImageLoaderManager.getImageLoader(mContext);
mOptions = ImageLoaderManager.getCacheOnDiskOptions(mContext);
init();
// DisplayMetrics dm = mContext.getResources().getDisplayMetrics();
mTitleHeight = ShowUtils.dip2px(48);//设置游标高度
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
ViewGroup.LayoutParams vp = getLayoutParams();
if (vp != null) { //设置视图的宽高
vp.width = mWidth;
vp.height = mHeight;
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
private void initView() {
mPager = new ViewPager(mContext);
RelativeLayout.LayoutParams rp = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
addView(mPager, rp);
}
/**
* 初始化指示游标
*/
private void initTipView() {
if (mTipView == null) {
RelativeLayout.LayoutParams rp = new RelativeLayout.LayoutParams(10, 10);
rp.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);//显示在父控件的底部
rp.bottomMargin = mTitleHeight;//游标的高度
mTipView = new TipView(mContext, mDatas.size());
addView(mTipView, rp);
} else {
mTipView.setCount(mDatas.size());
}
}
@Override
public void upDate() {
getData();
}
@Override
public void init() {
getData();
}
@Override
public void startAnimation() {
if (mDatas.size() == 0) {
return;
}
Message msg = sHandler.obtainMessage(START_SCROLL);
msg.obj = mPager;
msg.arg1 = (mPager.getCurrentItem() + 1);
sHandler.sendMessageDelayed(msg, SHOW_TIME);
}
@Override
public void stopAnimation() {
sHandler.removeMessages(START_SCROLL);
sHandler.removeMessages(SCROLL_NEXT);
}
/**
* 获取viewpager要显示的数据
*/
private void getData() {
String[] imageData = new String[]{"http://f.hiphotos.baidu.com/image/h%3D360/sign=e105b9f1d61b0ef473e89e58edc651a1/b151f8198618367a9f738e022a738bd4b21ce573.jpg",
"http://c.hiphotos.baidu.com/image/h%3D360/sign=b8cea9e92b738bd4db21b437918b876c/f7246b600c3387448982f948540fd9f9d72aa0bb.jpg",
"http://a.hiphotos.baidu.com/image/h%3D360/sign=3da95d01e7dde711f8d245f097eecef4/71cf3bc79f3df8dc39cb6295cf11728b461028c4.jpg",
"http://d.hiphotos.baidu.com/image/h%3D360/sign=410c3c96a60f4bfb93d09852334f788f/10dfa9ec8a136327a1de913a938fa0ec08fac78c.jpg",
"http://e.hiphotos.baidu.com/image/h%3D360/sign=f6600b1613dfa9ece22e501152d1f754/342ac65c10385343ff41ee2b9113b07eca808829.jpg"};
for (int i = 0; i < 5; i++) {
HeadViewEntity info = new HeadViewEntity();
info.setImageUrl(imageData[i]);
info.setTitle("我不做大哥好多年"+i);
info.setUrl("www.baidu.com");
mDatas.add(info);
}
sHandler.postDelayed(new Runnable() {
@Override
public void run() {
stopAnimation();
initTipView();
mPager.setAdapter(new RecommendAdapter());
mPager.setCurrentItem(10000 * mDatas.size());//一开始设置成这样的话就可以向左无限滚动了
}
},2000);
}
/**
* viewpager子项内容
*/
private class RecommendAdapter extends PagerAdapter {
/**
* 填充子项视图的内容
* @param container 父控件 viewpager
* @param position 子项的位置
* @return 返回子项视图
*/
@Override
public Object instantiateItem(ViewGroup container, int position) {
int curPos = position % mDatas.size();
View view = View.inflate(mContext, R.layout.layout_recommend_item, null);
ViewGroup.LayoutParams vp = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
ImageView iv = (ImageView) view.findViewById(R.id.iv_pic);
TextView tv = (TextView) view.findViewById(R.id.tv_desc);
tv.setText(mDatas.get(curPos).getTitle());
mLoader.displayImage(mDatas.get(curPos).getImageUrl(), iv, mOptions);
container.addView(view, vp);
view.setTag(curPos);
view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
return view;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
@Override
public int getCount() {
return Integer.MAX_VALUE;
}
@Override
public boolean isViewFromObject(View view, Object o) {
return view == o;
}
}
private class MOnPagerChangeListener implements ViewPager.OnPageChangeListener {
private int curState;
@Override
public void onPageScrolled(int i, float v, int i1) {
}
@Override
public void onPageScrollStateChanged(int i) {
curState = i;
if(i == ViewPager.SCROLL_STATE_DRAGGING){ //viewpager正在被拖动的时候
stopAnimation();
}else { //没有可执行消息时候添加消息 实现自动滚动
if(!(sHandler.hasMessages(START_SCROLL)&&sHandler.hasMessages(SCROLL_NEXT))){
startAnimation();
}
}
}
@Override
public void onPageSelected(final int i) { //页面跳转后得到调用
sHandler.removeMessages(SCROLL_NEXT);
sHandler.removeMessages(START_SCROLL);
if(curState == ViewPager.SCROLL_STATE_DRAGGING){
return;
}
Message msg = sHandler.obtainMessage(SCROLL_NEXT);
msg.arg1 = i + 1;
msg.obj = mPager;
sHandler.sendMessageDelayed(msg, SHOW_TIME);
mTipView.setCurPostion(i % mDatas.size());
}
}
/**
* 指示游标
*/
private class TipView extends View {
private int mPadding;
private int mCount;
private int mCurPos;
private Paint mNorPaint;//未被选中的颜色
private Paint mSelPaint;//被选中的颜色 白色
private int mHeight;
public TipView(Context context, int count) {
super(context);
mNorPaint = new Paint();
mNorPaint.setAntiAlias(true);
int selHeight = ShowUtils.dip2px(2);
int norHeight = ShowUtils.dip2px(1);
mHeight = ShowUtils.dip2px(2);
mNorPaint.setStrokeWidth(norHeight);
mNorPaint.setColor(Color.argb(80, 255, 255, 255));
mSelPaint = new Paint();
mSelPaint.setAntiAlias(true);
mSelPaint.setStrokeWidth(selHeight);
mSelPaint.setColor(Color.WHITE);
mCount = count;
mPadding = ShowUtils.dip2px(0);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int ow = (getWidth()-2 * mPadding)/ mCount;
int y = getHeight() / 2;
canvas.drawLine(mPadding, y, mCurPos * ow + mPadding, y, mNorPaint);
canvas.drawLine(mCurPos * ow + mPadding, y, (mCurPos + 1) * ow + mPadding, y, mSelPaint);
canvas.drawLine((mCurPos + 1) * ow + mPadding, y, getWidth() - mPadding, y, mNorPaint);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
ViewGroup.LayoutParams vp = getLayoutParams();
vp.width = ViewGroup.LayoutParams.MATCH_PARENT;
vp.height = mHeight;
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
public void setCurPostion(int pos) {
mCurPos = pos;
invalidate();
}
public void setCount(int count) {
mCount = count;
}
}
}
然后提供了一个接口调用：
/**
* RecommendView接口
*/
public interface IRecommend {
void upDate();
void init();
void startAnimation();
void stopAnimation();
}
图片的加载用到了ImageLoad库：
import android.content.Context;
import android.graphics.Bitmap;
import com.nostra13.universalimageloader.cache.disc.impl.UnlimitedDiskCache;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
import com.nostra13.universalimageloader.core.assist.ImageScaleType;
import com.papau.show.constant.Constants;
import java.io.File;
public class ImageLoaderManager {
/**
* 不带硬盘缓存的options
*
* @param context
* @return
*/
public static synchronized DisplayImageOptions getCacheOnMemoryOptions(Context context) {
DisplayImageOptions options = new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisk(false)
.imageScaleType(ImageScaleType.EXACTLY_STRETCHED)
.bitmapConfig(Bitmap.Config.ARGB_8888)
// .showImageOnLoading(
// context.getResources().getDrawable(
// R.drawable.loading_wait))
// .showImageOnFail(
// context.getResources().getDrawable(
// R.drawable.loading_wait))
.build();
return options;
}
public static synchronized DisplayImageOptions getCircleOptions(Context context) {
DisplayImageOptions options = new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisk(false)
.imageScaleType(ImageScaleType.EXACTLY_STRETCHED)
.bitmapConfig(Bitmap.Config.ARGB_8888)
// .showImageOnLoading(
// context.getResources().getDrawable(
// R.drawable.ic_user_head_hint))
// .showImageOnFail(
// context.getResources().getDrawable(
// R.drawable.ic_user_head_hint))
.build();
return options;
}
/**
* 获取在硬盘中缓存options
*
* @param context
* @return options
*/
public static synchronized DisplayImageOptions getCacheOnDiskOptions(
Context context) {
DisplayImageOptions options = new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisk(true)
.imageScaleType(ImageScaleType.EXACTLY)
.bitmapConfig(Bitmap.Config.ARGB_8888)
// .showImageOnLoading(
// context.getResources().getDrawable(
// R.drawable.loading_wait))
// .showImageOnFail(
// context.getResources().getDrawable(
// R.drawable.loading_wait))
.build();
return options;
}
/**
* 获取imageLoader 单例
*
* @param context
* @return
*/
public static synchronized ImageLoader getImageLoader(Context context) {
ImageLoader imageLoader = ImageLoader.getInstance();
File cacheDir = new File(Constants.sPicCacheLocalPath);
ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(
context).diskCache(new UnlimitedDiskCache(cacheDir))
.threadPoolSize(3)
.diskCacheExtraOptions(480, 320, null)
.build();
imageLoader.init(config);
return imageLoader;
}
}
使用方法
DisplayMetrics dm = getActivity().getResources().getDisplayMetrics();
RecommendView rv = new RecommendView(getActivity(),dm.widthPixels ,(dm.widthPixels)/2);
headViewPager.addView(rv);
以上所述是小编给大家介绍的Android简单实现无限滚动自动滚动的ViewPager，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！