Android 轮番图

jar compile’com.android.support:recyclerview-v7:26+’ compile’com.github.bumptech.glide:glide:3.7.0’

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代码1.自定义控件

/* Created by 周岩 on 17/8/24.*/

public class BannerRecyclerView extends RecyclerView {

private static final intSCROLL=1;

private intstartX;

private intstartY;

privateHandlermHandler=newHandler() {

@Override

public void handleMessage(Message msg) {

super.handleMessage(msg);

switch(msg.what) {

caseSCROLL:

smoothScrollToPosition(++mCurrentPosition);

break;

}

}

};

private booleanisTouching=false;

private booleanisPlaying=false;

private intmPeriod=3500;

private TimermTimer;

private TimerTaskmTimerTask;

private RunnablemPlayTask=newRunnable() {

@Override

public voidrun() {

if(!isTouching) {

mHandler.sendEmptyMessage(SCROLL);

mHandler.postDelayed(this,mPeriod);

}

}

};;

public int getCurrentPosition() {

return mCurrentPosition;

}

public void setCurrentPosition(intcurrentPosition) {

mCurrentPosition= currentPosition;

}

private intmCurrentPosition;

public BannerRecyclerView(Context context) {

super(context);

}

public BannerRecyclerView(Context context,@NullableAttributeSet attrs) {

super(context, attrs);

newPagerSnapHelper().attachToRecyclerView(this);

addOnScrollListener(newOnScrollListener() {

@Override

public voidonScrollStateChanged(RecyclerView recyclerView,intnewState) {

super.onScrollStateChanged(recyclerView, newState);

switch(newState) {

caseRecyclerView.SCROLL_STATE_IDLE:

int firstVisibleItemPosition = ((LinearLayoutManager) recyclerView.getLayoutManager()).findFirstVisibleItemPosition();

int lastVisibleItemPosition = ((LinearLayoutManager) recyclerView.getLayoutManager()).findLastVisibleItemPosition();

if(lastVisibleItemPosition-firstVisibleItemPosition==2&&mCurrentPosition!=firstVisibleItemPosition+1){

mCurrentPosition=firstVisibleItemPosition+1;

}

break;

}}});}

public BannerRecyclerView(Context context,@NullableAttributeSet attrs,intdefStyle) {

this(context, attrs);

}

@Override

public boolean dispatchTouchEvent(MotionEvent ev) {

switch(ev.getAction()) {

caseMotionEvent.ACTION_DOWN:

isTouching=true;

startX= (int)ev.getX();

startY= (int)ev.getY();

getParent().requestDisallowInterceptTouchEvent(true);

mHandler.removeCallbacksAndMessages(null);

break;

caseMotionEvent.ACTION_MOVE:

intmoveX = (int) ev.getX();

intmoveY = (int) ev.getY();

intdisX = moveX -startX;

intdisY = moveY -startY;

booleanisHorizontalMove = Math.abs(disX) *1.5> Math.abs(disY);

getParent().requestDisallowInterceptTouchEvent(isHorizontalMove);

break;

caseMotionEvent.ACTION_CANCEL:

caseMotionEvent.ACTION_UP:

isTouching=false;

resetAutoScroll();

break;

}

return super.dispatchTouchEvent(ev);

}

private class PagerSnapHelperextendsLinearSnapHelper {

@Override

public intfindTargetSnapPosition(LayoutManager layoutManager,intvelocityX,intvelocityY) {

inttargetPos =super.findTargetSnapPosition(layoutManager, velocityX, velocityY);

finalView currentView = findSnapView(layoutManager);

if(targetPos != RecyclerView.NO_POSITION&& currentView !=null) {

intcurrentPos = layoutManager.getPosition(currentView);

intfirst = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();

intlast = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();

currentPos = targetPos < currentPos ? last : (targetPos > currentPos ? first : currentPos);

targetPos = targetPos < currentPos ? currentPos -1: (targetPos > currentPos ? currentPos +1: currentPos);

}

returntargetPos;

}}

public void startAutoScroll() {

mHandler.postDelayed(mPlayTask,100);

}

public void resetAutoScroll(){

mHandler.postDelayed(mPlayTask,mPeriod);

}}

2 代码

（1）工具类

/*@author zhouyan*/

public class GlideManager {

private static final intduration=300;//渐显动画时间

private static final intplaceholder= R.drawable.img_index_top;//占位图

private static final intheader_placeholder= R.drawable.img_index_top;//圆形头像占位图

private static final interror=0;//加载失败图R.drawable.ls_logo

/* 加载网络图片*/

public static void setNormalImage(Activity context, String url, ImageView iv) {

if(context !=null)

Glide.with(context.getApplicationContext()).load(url).placeholder(placeholder)//加载之前的 默认占位图

.error(error)//图片无法加载时的 默认占位图

.crossFade(duration)//淡入淡出动画 默认300ms

.centerCrop().into(iv);}

/* 加载本地图片*/

public static void setNormalImage(Activity context,intresId, ImageView iv) {

if(context !=null)

Glide.with(context.getApplicationContext()).load(resId).placeholder(placeholder)//加载之前的 默认占位图.error(error)//图片无法加载时的 默认占位图

.crossFade(duration)//淡入淡出动画 默认300ms.centerCrop().into(iv);}

}

（2）activity 代码

public class MainActivity extends AppCompatActivity {

private BannerRecyclerView mBannerRecyclerView;

private ArrayList imageUrls;

private RecyclerView.Adapter mRVAdapter;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mBannerRecyclerView= (BannerRecyclerView) findViewById(R.id.brv_show);

imageUrls=newArrayList();

imageUrls.add(“http://img.taodiantong.cn/v55183/infoimg/2013-07/130720115322ky.jpg“);

imageUrls.add(“http://pic30.nipic.com/20130626/8174275_085522448172_2.jpg“);

imageUrls.add(“http://pic18.nipic.com/20111215/577405_080531548148_2.jpg“);

imageUrls.add(“http://pic15.nipic.com/20110722/2912365_092519919000_2.jpg“);

imageUrls.add(“http://pic.58pic.com/58pic/12/64/27/55U58PICrdX.jpg“);

LinearLayoutManager mLinearLayoutManager =newLinearLayoutManager(this, LinearLayoutManager.HORIZONTAL,false);

mBannerRecyclerView.setLayoutManager(mLinearLayoutManager);

view(imageUrls,this);

}

private void view(final ArrayList mBannerinfosBeanList,final Activity context) {

if(mBannerRecyclerView.getAdapter() ==null) {

mRVAdapter=newRecyclerView.Adapter() {

@Override

publicViewHolderRV onCreateViewHolder(ViewGroup parent,int viewType) {

ViewHolderRV holderRV =new ViewHolderRV(LayoutInflater.from(context).inflate(R.layout.item_rv, parent,false));

return holderRV;

}

@Override

public void onBindViewHolder(ViewHolderRV holder,int position) {

if(holder!=null){

if(mBannerinfosBeanList!=null&&mBannerinfosBeanList.size() !=0) {

position = position %mBannerinfosBeanList.size();

//”?width=400&height=220”能过减小图片大小

GlideManager.setNormalImage(context,mBannerinfosBeanList.get(position)+”?width=400&height=220”, holder.mIv);}else{GlideManager.setNormalImage(context, R.drawable.img_index_top, holder.mIv);}}}

@Override

public int getItemCount() {returnInteger.MAX_VALUE>>2;}};

mBannerRecyclerView.setAdapter(mRVAdapter);

mBannerRecyclerView.setCurrentPosition(200* mBannerinfosBeanList.size() -1);

mBannerRecyclerView.scrollToPosition(mBannerRecyclerView.getCurrentPosition());

if(mBannerinfosBeanList.size()!=1)mBannerRecyclerView.startAutoScroll();}}

//适配器

private class ViewHolderRV extends RecyclerView.ViewHolder {

public ImageView mIv;

publicViewHolderRV(View itemView) {super(itemView);mIv= (ImageView) itemView.findViewById(R.id.iv_item_home);}}}