DataSetObserver使用——自定义View之二

这是一个开源项目：https://github.com/Jude95/RollViewPager图片轮播控件，写的特别好，有必要好好总结一下。

RollViewPager 是一个ViewGroup，里面封装了ViewPager和指示器(HintView)。里面有很多东西值得我们学习：

1.间隔时间自己滑动

2.手动点击就不自动滑动（事件处理）

3.可以动态设置和更新页面和指示器

我这篇文章主要想研究里面的观察者，怎么样通过DataSetObserver，实现no动态设置页面个数和指示器个数。

package lib.util.open.rollviewpage;import android.content.Context;import android.content.res.TypedArray;import android.database.DataSetObserver;import android.graphics.Color;import android.graphics.drawable.GradientDrawable;import android.os.Handler;import android.os.Message;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.util.AttributeSet;import android.view.GestureDetector;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.view.animation.Interpolator;import android.widget.RelativeLayout;import android.widget.Scroller;import lib.util.open.R;import lib.util.open.rollviewpage.adapter.LoopPagerAdapter;import lib.util.open.rollviewpage.hintview.ColorPointHintView;import java.lang.ref.WeakReference;import java.lang.reflect.Field;import java.util.Timer;import java.util.TimerTask;/** * 支持轮播和提示的的viewpager * https://github.com/Jude95/RollViewPager */public class RollPagerView extends RelativeLayout implements OnPageChangeListener {private ViewPager mViewPager;private PagerAdapter mAdapter;private OnItemClickListener mOnItemClickListener;    private GestureDetector mGestureDetector;private long mRecentTouchTime;//播放延迟private int delay;//hint位置private int gravity;//hint颜色private int color;//hint透明度private int alpha;private int paddingLeft;private int paddingTop;private int paddingRight;private int paddingBottom;private View mHintView;private Timer timer;public interface HintViewDelegate{        void setCurrentPosition(int position, HintView hintView);        void initView(int length, int gravity, HintView hintView);    }    private HintViewDelegate mHintViewDelegate = new HintViewDelegate() {        @Override        public void setCurrentPosition(int position,HintView hintView) {            if(hintView!=null)                hintView.setCurrent(position);        }        @Override        public void initView(int length, int gravity,HintView hintView) {            if (hintView!=null)            hintView.initView(length,gravity);        }    };public RollPagerView(Context context){this(context,null);}public RollPagerView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public RollPagerView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initView(attrs);}/** * 读取提示形式  和   提示位置   和    播放延迟 * @param attrs */private void initView(AttributeSet attrs){if(mViewPager!=null){removeView(mViewPager);}TypedArray type = getContext().obtainStyledAttributes(attrs, R.styleable.RollViewPager);gravity = type.getInteger(R.styleable.RollViewPager_rollviewpager_hint_gravity, 1);delay = type.getInt(R.styleable.RollViewPager_rollviewpager_play_delay, 0);color = type.getColor(R.styleable.RollViewPager_rollviewpager_hint_color, Color.BLACK);alpha = type.getInt(R.styleable.RollViewPager_rollviewpager_hint_alpha, 0);paddingLeft = (int) type.getDimension(R.styleable.RollViewPager_rollviewpager_hint_paddingLeft, 0);paddingRight = (int) type.getDimension(R.styleable.RollViewPager_rollviewpager_hint_paddingRight, 0);paddingTop = (int) type.getDimension(R.styleable.RollViewPager_rollviewpager_hint_paddingTop, 0);paddingBottom = (int) type.getDimension(R.styleable.RollViewPager_rollviewpager_hint_paddingBottom, Util.dip2px(getContext(),4));mViewPager = new ViewPager(getContext());mViewPager.setId(R.id.rollViewpager_inner);mViewPager.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));addView(mViewPager);type.recycle();initHint(new ColorPointHintView(getContext(),Color.parseColor("#E3AC42"),Color.parseColor("#88ffffff")));        //手势处理        mGestureDetector = new GestureDetector(getContext(), new GestureDetector.SimpleOnGestureListener(){            @Override            public boolean onSingleTapUp(MotionEvent e) {                if (mOnItemClickListener!=null){                    if (mAdapter instanceof LoopPagerAdapter){//原谅我写了这么丑的代码                        mOnItemClickListener.onItemClick(mViewPager.getCurrentItem()%((LoopPagerAdapter) mAdapter).getRealCount());                    }else {                        mOnItemClickListener.onItemClick(mViewPager.getCurrentItem());                    }                }                return super.onSingleTapUp(e);            }        });}    private final static class TimeTaskHandler extends Handler{        private WeakReference<RollPagerView> mRollPagerViewWeakReference;        public TimeTaskHandler(RollPagerView rollPagerView) {            this.mRollPagerViewWeakReference = new WeakReference<>(rollPagerView);        }        @Override        public void handleMessage(Message msg) {            RollPagerView rollPagerView = mRollPagerViewWeakReference.get();            int cur = rollPagerView.getViewPager().getCurrentItem()+1;            if(cur>=rollPagerView.mAdapter.getCount()){                cur=0;            }            rollPagerView.getViewPager().setCurrentItem(cur);            rollPagerView.mHintViewDelegate.setCurrentPosition(cur, (HintView) rollPagerView.mHintView);if (rollPagerView.mAdapter.getCount()<=1)rollPagerView.stopPlay();        }    }    private TimeTaskHandler mHandler = new TimeTaskHandler(this);    private static class WeakTimerTask extends TimerTask{        private WeakReference<RollPagerView> mRollPagerViewWeakReference;        public WeakTimerTask(RollPagerView mRollPagerView) {            this.mRollPagerViewWeakReference = new WeakReference<>(mRollPagerView);        }        @Override        public void run() {            RollPagerView rollPagerView = mRollPagerViewWeakReference.get();            if (rollPagerView!=null){                if(rollPagerView.isShown() && System.currentTimeMillis()-rollPagerView.mRecentTouchTime>rollPagerView.delay){                    rollPagerView.mHandler.sendEmptyMessage(0);                }            }else{                cancel();            }        }    }/** * 开始播放 * 仅当view正在显示 且 触摸等待时间过后 播放 */private void startPlay(){if(delay<=0||mAdapter==null||mAdapter.getCount()<=1){return;}if (timer!=null){timer.cancel();}timer = new Timer();//用一个timer定时设置当前项为下一项timer.schedule(new WeakTimerTask(this), delay, delay);}    private void stopPlay(){        if (timer!=null){            timer.cancel();            timer = null;        }    }    public void setHintViewDelegate(HintViewDelegate delegate){        this.mHintViewDelegate = delegate;    }private void initHint(HintView hintview){if(mHintView!=null){removeView(mHintView);}if(hintview == null||!(hintview instanceof HintView)){return;}mHintView = (View) hintview;loadHintView();}/** * 加载hintview的容器 */private void loadHintView(){addView(mHintView);mHintView.setPadding(paddingLeft, paddingTop, paddingRight, paddingBottom);LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);lp.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);((View) mHintView).setLayoutParams(lp);GradientDrawable gd = new GradientDrawable();gd.setColor(color);gd.setAlpha(alpha);mHintView.setBackgroundDrawable(gd);        mHintViewDelegate.initView(mAdapter == null ? 0 : mAdapter.getCount(), gravity, (HintView) mHintView);}/** * 设置viewager滑动动画持续时间 * @param during */public void setAnimationDurtion(final int during){try {// viePager平移动画事件(反射)Field mField = ViewPager.class.getDeclaredField("mScroller");mField.setAccessible(true);Scroller mScroller = new Scroller(getContext(),// 动画效果与ViewPager的一致                    new Interpolator() {                        public float getInterpolation(float t) {                            t -= 1.0f;                            return t * t * t * t * t + 1.0f;                        }                    }) {                @Override                public void startScroll(int startX, int startY, int dx,                                        int dy, int duration) {                    // 如果手工滚动,则加速滚动                    if (System.currentTimeMillis() - mRecentTouchTime > delay) {                        duration = during;                    } else {                        duration /= 2;                    }                    super.startScroll(startX, startY, dx, dy, duration);                }@Overridepublic void startScroll(int startX, int startY, int dx,int dy) {super.startScroll(startX, startY, dx, dy,during);}};mField.set(mViewPager, mScroller);} catch (NoSuchFieldException e) {e.printStackTrace();} catch (IllegalArgumentException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}}    public void setPlayDelay(int delay){        this.delay = delay;        startPlay();    }    public void pause(){        stopPlay();    }    public void resume(){        startPlay();    }    public boolean isPlaying(){        return timer!=null;    }    public void setOnItemClickListener(OnItemClickListener listener){        this.mOnItemClickListener = listener;    }/** * 设置提示view的位置 * */public void setHintPadding(int left,int top,int right,int bottom){paddingLeft = left;paddingTop = top;paddingRight = right;paddingBottom = bottom;mHintView.setPadding(paddingLeft, paddingTop, paddingRight, paddingBottom);}/** * 设置提示view的透明度 * @param alpha 0为全透明  255为实心 */public void setHintAlpha(int alpha){this.alpha = alpha;initHint((HintView)mHintView);}/** * 支持自定义hintview * 只需new一个实现HintView的View传进来 * 会自动将你的view添加到本View里面。重新设置LayoutParams。 * @param hintview */public void setHintView(HintView hintview){if (mHintView != null) {removeView(mHintView);}this.mHintView = (View) hintview;if (hintview!=null&&hintview instanceof View){initHint(hintview);}}/** * 取真正的Viewpager * @return */public ViewPager getViewPager() {return mViewPager;}/** * 设置Adapter * @param adapter */public void setAdapter(PagerAdapter adapter){        mViewPager.setAdapter(adapter);        mViewPager.addOnPageChangeListener(this);mAdapter = adapter;dataSetChanged();//关键的一步adapter.registerDataSetObserver(new JPagerObserver());    }/** * 用来实现adapter的notifyDataSetChanged通知HintView变化 */private class JPagerObserver extends DataSetObserver {@Overridepublic void onChanged() {dataSetChanged();}@Overridepublic void onInvalidated() {dataSetChanged();}}private void dataSetChanged(){if(mHintView!=null) {mHintViewDelegate.initView(mAdapter.getCount(), gravity, (HintView) mHintView);mHintViewDelegate.setCurrentPosition(mViewPager.getCurrentItem(), (HintView) mHintView);}        startPlay();    }/** * 为了实现触摸时和过后一定时间内不滑动,这里拦截 * @param ev * @return */    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {mRecentTouchTime = System.currentTimeMillis();        mGestureDetector.onTouchEvent(ev);        return super.dispatchTouchEvent(ev);    }    @Overridepublic void onPageScrollStateChanged(int arg0) {// TODO Auto-generated method stub}@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {// TODO Auto-generated method stub}@Overridepublic void onPageSelected(int arg0) {        mHintViewDelegate.setCurrentPosition(arg0, (HintView) mHintView);}}