Android开发之app基础---自动轮播图
来源：互联网 发布：淘宝客在哪里设置 编辑：程序博客网 时间：2024/04/28 17:09
前面已经介绍了app基本框架，框架搭好之后自然要进入到页面中，最常用的自然是我们首页的轮播图了，下面就来分享下我看到的比较好的一个banner轮播图的代码：
- 三个自定义view FlowIndictor CircleFlowIndictor，ViewFlow,封装了banner图所需的逻辑
- FlowView的设置轮播图片
- 创建BannerAdapter 适配器加载图片
ok说到这就基本上完了，是不是觉得很简单呢，他不需要自己再写一个viewpager，而且避免了一个问题，就是当图片跳到最后一张的时候不会很突兀的跳到第一张，我想刚开始很多人遇到过这个问题吧，废话讲了这么多，上代码吧！
CircleFlowIndicator
package com.example.bannerdemo;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.Paint.Style;import android.os.AsyncTask;import android.util.AttributeSet;import android.view.View;import android.view.animation.Animation;import android.view.animation.Animation.AnimationListener;import android.view.animation.AnimationUtils;/** * A FlowIndicator which draws circles (one for each view). * <br/> * Availables attributes are:<br/> * <ul> * activeColor: Define the color used to draw the active circle (default to white) * </ul> * <ul> * inactiveColor: Define the color used to draw the inactive circles (default to 0x44FFFFFF) * </ul> * <ul> * inactiveType: Define how to draw the inactive circles, either stroke or fill (default to stroke) * </ul> * <ul> * activeType: Define how to draw the active circle, either stroke or fill (default to fill) * </ul> * <ul> * fadeOut: Define the time (in ms) until the indicator will fade out (default to 0 = never fade out) * </ul> * <ul> * radius: Define the circle radius (default to 4.0) * </ul> */public class CircleFlowIndicator extends View implements FlowIndicator, AnimationListener { private static final int STYLE_STROKE = 0; private static final int STYLE_FILL = 1; private float radius = 4; private float circleSeparation = 2*radius+radius; private float activeRadius = 0.5f; private int fadeOutTime = 0; private final Paint mPaintInactive = new Paint(Paint.ANTI_ALIAS_FLAG); private final Paint mPaintActive = new Paint(Paint.ANTI_ALIAS_FLAG); private ViewFlow viewFlow; private int currentScroll = 0; private int flowWidth = 0; private FadeTimer timer; public AnimationListener animationListener = this; private Animation animation; private boolean mCentered = false; /** * Default constructor * * @param context */ public CircleFlowIndicator(Context context) { super(context); initColors(0xFFFFFFFF, 0xFFFFFFFF, STYLE_FILL, STYLE_STROKE); } /** * The contructor used with an inflater * * @param context * @param attrs */ public CircleFlowIndicator(Context context, AttributeSet attrs) { super(context, attrs); // Retrieve styles attributs TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleFlowIndicator); // Gets the inactive circle type, defaulting to "fill" int activeType = a.getInt(R.styleable.CircleFlowIndicator_activeType, STYLE_FILL); int activeDefaultColor = 0xFFFFFFFF; // Get a custom inactive color if there is one int activeColor = a .getColor(R.styleable.CircleFlowIndicator_activeColor, activeDefaultColor); // Gets the inactive circle type, defaulting to "stroke" int inactiveType = a.getInt( R.styleable.CircleFlowIndicator_inactiveType, STYLE_STROKE); int inactiveDefaultColor = 0x44FFFFFF; // Get a custom inactive color if there is one int inactiveColor = a.getColor( R.styleable.CircleFlowIndicator_inactiveColor, inactiveDefaultColor); // Retrieve the radius radius = a.getDimension(R.styleable.CircleFlowIndicator_radius, 4.0f); circleSeparation = a.getDimension(R.styleable.CircleFlowIndicator_circleSeparation, 2*radius+radius); activeRadius = a.getDimension(R.styleable.CircleFlowIndicator_activeRadius, 0.5f); // Retrieve the fade out time fadeOutTime = a.getInt(R.styleable.CircleFlowIndicator_fadeOut, 0); mCentered = a.getBoolean(R.styleable.CircleFlowIndicator_centered, false); initColors(activeColor, inactiveColor, activeType, inactiveType); } private void initColors(int activeColor, int inactiveColor, int activeType, int inactiveType) { // Select the paint type given the type attr switch (inactiveType) { case STYLE_FILL: mPaintInactive.setStyle(Style.FILL); break; default: mPaintInactive.setStyle(Style.STROKE); } mPaintInactive.setColor(inactiveColor); // Select the paint type given the type attr switch (activeType) { case STYLE_STROKE: mPaintActive.setStyle(Style.STROKE); break; default: mPaintActive.setStyle(Style.FILL); } mPaintActive.setColor(activeColor); } /* * (non-Javadoc) * * @see android.view.View#onDraw(android.graphics.Canvas) */ @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); int count = 3; if (viewFlow != null) { count = viewFlow.getViewsCount(); } //this is the amount the first circle should be offset to make the entire thing centered float centeringOffset = 0; int leftPadding = getPaddingLeft(); // Draw stroked circles for (int iLoop = 0; iLoop < count; iLoop++) { canvas.drawCircle(leftPadding + radius + (iLoop * circleSeparation) + centeringOffset, getPaddingTop() + radius, radius, mPaintInactive); } float cx = 0; if (flowWidth != 0) { // Draw the filled circle according to the current scroll cx = (currentScroll * circleSeparation) / flowWidth; } // The flow width has been upadated yet. Draw the default position canvas.drawCircle(leftPadding + radius + cx+centeringOffset, getPaddingTop() + radius, radius + activeRadius, mPaintActive); } /* * (non-Javadoc) * * @see * org.taptwo.android.widget.ViewFlow.ViewSwitchListener#onSwitched(android * .view.View, int) */ @Override public void onSwitched(View view, int position) { } /* * (non-Javadoc) * * @see * org.taptwo.android.widget.FlowIndicator#setViewFlow(org.taptwo.android * .widget.ViewFlow) */ @Override public void setViewFlow(ViewFlow view) { resetTimer(); viewFlow = view; flowWidth = viewFlow.getWidth(); invalidate(); } /* * (non-Javadoc) * * @see org.taptwo.android.widget.FlowIndicator#onScrolled(int, int, int, * int) */ @Override public void onScrolled(int h, int v, int oldh, int oldv) { setVisibility(View.VISIBLE); resetTimer(); flowWidth = viewFlow.getWidth(); if(viewFlow.getViewsCount()*flowWidth!=0){ currentScroll = h%(viewFlow.getViewsCount()*flowWidth); }else { currentScroll = h; } invalidate(); } /* * (non-Javadoc) * * @see android.view.View#onMeasure(int, int) */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec)); } /** * Determines the width of this view * * @param measureSpec * A measureSpec packed into an int * @return The width of the view, honoring constraints from measureSpec */ private int measureWidth(int measureSpec) { int result = 0; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); // We were told how big to be if (specMode == MeasureSpec.EXACTLY) { result = specSize; } // Calculate the width according the views count else { int count = 3; if (viewFlow != null) { count = viewFlow.getViewsCount(); } float temp = circleSeparation - 2*radius; result = (int) (getPaddingLeft() + getPaddingRight() + (count * 2 * radius) + (count - 1) * temp + 1); // Respect AT_MOST value if that was what is called for by // measureSpec if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return result; } /** * Determines the height of this view * * @param measureSpec * A measureSpec packed into an int * @return The height of the view, honoring constraints from measureSpec */ private int measureHeight(int measureSpec) { int result = 0; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); // We were told how big to be if (specMode == MeasureSpec.EXACTLY) { result = specSize; } // Measure the height else { result = (int) (2 * radius + getPaddingTop() + getPaddingBottom() + 1); // Respect AT_MOST value if that was what is called for by // measureSpec if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return result; } /** * Sets the fill color * * @param color * ARGB value for the text */ public void setFillColor(int color) { mPaintActive.setColor(color); invalidate(); } /** * Sets the stroke color * * @param color * ARGB value for the text */ public void setStrokeColor(int color) { mPaintInactive.setColor(color); invalidate(); } /** * Resets the fade out timer to 0. Creating a new one if needed */ private void resetTimer() { // Only set the timer if we have a timeout of at least 1 millisecond if (fadeOutTime > 0) { // Check if we need to create a new timer if (timer == null || timer._run == false) { // Create and start a new timer timer = new FadeTimer(); timer.execute(); } else { // Reset the current tiemr to 0 timer.resetTimer(); } } } /** * Counts from 0 to the fade out time and animates the view away when * reached */ private class FadeTimer extends AsyncTask<Void, Void, Void> { // The current count private int timer = 0; // If we are inside the timing loop private boolean _run = true; public void resetTimer() { timer = 0; } @Override protected Void doInBackground(Void... arg0) { while (_run) { try { // Wait for a millisecond Thread.sleep(1); // Increment the timer timer++; // Check if we've reached the fade out time if (timer == fadeOutTime) { // Stop running _run = false; } } catch (InterruptedException e) { e.printStackTrace(); } } return null; } @Override protected void onPostExecute(Void result) { animation = AnimationUtils.loadAnimation(getContext(), android.R.anim.fade_out); animation.setAnimationListener(animationListener); startAnimation(animation); } } @Override public void onAnimationEnd(Animation animation) { setVisibility(View.GONE); } @Override public void onAnimationRepeat(Animation animation) { } @Override public void onAnimationStart(Animation animation) { }}FlowIndicator
package com.example.bannerdemo;/** * An interface which defines the contract between a ViewFlow and a * FlowIndicator.<br/> * A FlowIndicator is responsible to show an visual indicator on the total views * number and the current visible view.<br/> * */public interface FlowIndicator extends ViewFlow.ViewSwitchListener { /** * Set the current ViewFlow. This method is called by the ViewFlow when the * FlowIndicator is attached to it. * * @param view */ public void setViewFlow(ViewFlow view); /** * The scroll position has been changed. A FlowIndicator may implement this * method to reflect the current position * * @param h * @param v * @param oldh * @param oldv */ public void onScrolled(int h, int v, int oldh, int oldv);}ViewFlow
package com.example.bannerdemo;import java.util.ArrayList;import java.util.LinkedList;import android.content.Context;import android.content.res.Configuration;import android.content.res.TypedArray;import android.database.DataSetObserver;import android.os.Handler;import android.os.Message;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.ViewConfiguration;import android.view.ViewGroup;import android.view.ViewTreeObserver.OnGlobalLayoutListener;import android.widget.AbsListView;import android.widget.Adapter;import android.widget.AdapterView;import android.widget.Scroller;/** * A horizontally scrollable {@link ViewGroup} with items populated from an * {@link Adapter}. The ViewFlow uses a buffer to store loaded {@link View}s in. * The default size of the buffer is 3 elements on both sides of the currently * visible {@link View}, making up a total buffer size of 3 * 2 + 1 = 7. The * buffer size can be changed using the {@code sidebuffer} xml attribute. * */public class ViewFlow extends AdapterView<Adapter> { private static final int SNAP_VELOCITY = 1000; private static final int INVALID_SCREEN = -1; private final static int TOUCH_STATE_REST = 0; private final static int TOUCH_STATE_SCROLLING = 1; private LinkedList<View> mLoadedViews; private int mCurrentBufferIndex; private int mCurrentAdapterIndex; private int mSideBuffer = 2; private Scroller mScroller; private VelocityTracker mVelocityTracker; private int mTouchState = TOUCH_STATE_REST; private float mLastMotionX; private int mTouchSlop; private int mMaximumVelocity; private int mCurrentScreen; private int mNextScreen = INVALID_SCREEN; private boolean mFirstLayout = true; private ViewSwitchListener mViewSwitchListener; private Adapter mAdapter; private int mLastScrollDirection; private AdapterDataSetObserver mDataSetObserver; private FlowIndicator mIndicator; private int mLastOrientation = -1; private long timeSpan = 4500; private Handler handler; private OnGlobalLayoutListener orientationChangeListener = new OnGlobalLayoutListener() { @Override public void onGlobalLayout() { getViewTreeObserver().removeGlobalOnLayoutListener( orientationChangeListener); setSelection(mCurrentAdapterIndex); } }; /** * Receives call backs when a new {@link View} has been scrolled to. */ public static interface ViewSwitchListener { /** * This method is called when a new View has been scrolled to. * * @param view * the {@link View} currently in focus. * @param position * The position in the adapter of the {@link View} currently in focus. */ void onSwitched(View view, int position); } public ViewFlow(Context context) { super(context); mSideBuffer = 3; init(); } public ViewFlow(Context context, int sideBuffer) { super(context); mSideBuffer = sideBuffer; init(); } public ViewFlow(Context context, AttributeSet attrs) { super(context, attrs); TypedArray styledAttrs = context.obtainStyledAttributes(attrs,R.styleable.ViewFlow); mSideBuffer = styledAttrs.getInt(R.styleable.ViewFlow_sidebuffer, 3); init(); } private void init() { mLoadedViews = new LinkedList<View>(); mScroller = new Scroller(getContext()); final ViewConfiguration configuration = ViewConfiguration .get(getContext()); mTouchSlop = configuration.getScaledTouchSlop(); mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); } public void startAutoFlowTimer(){ handler = new Handler(){ @Override public void handleMessage(Message msg) { snapToScreen((mCurrentScreen+1)%getChildCount()); Message message = handler.obtainMessage(0); sendMessageDelayed(message, timeSpan); } }; Message message = handler.obtainMessage(0); handler.sendMessageDelayed(message, timeSpan); } public void stopAutoFlowTimer(){ if(handler!=null) handler.removeMessages(0); handler = null; } public void onConfigurationChanged(Configuration newConfig) { if (newConfig.orientation != mLastOrientation) { mLastOrientation = newConfig.orientation; getViewTreeObserver().addOnGlobalLayoutListener(orientationChangeListener); } } public int getViewsCount() { return mSideBuffer; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); final int width = MeasureSpec.getSize(widthMeasureSpec); final int widthMode = MeasureSpec.getMode(widthMeasureSpec); if (widthMode != MeasureSpec.EXACTLY && !isInEditMode()) { throw new IllegalStateException( "ViewFlow can only be used in EXACTLY mode."); } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode != MeasureSpec.EXACTLY && !isInEditMode()) { throw new IllegalStateException( "ViewFlow can only be used in EXACTLY mode."); } // The children are given the same width and height as the workspace final int count = getChildCount(); for (int i = 0; i < count; i++) { getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec); } if (mFirstLayout) { mScroller.startScroll(0, 0, mCurrentScreen * width, 0, 0); mFirstLayout = false; } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { int childLeft = 0; final int count = getChildCount(); for (int i = 0; i < count; i++) { final View child = getChildAt(i); if (child.getVisibility() != View.GONE) { final int childWidth = child.getMeasuredWidth(); child.layout(childLeft, 0, childLeft + childWidth, child.getMeasuredHeight()); childLeft += childWidth; } } } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { if(mSideBuffer<2){ return false; } if (getChildCount() == 0) return false; if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); final int action = ev.getAction(); final float x = ev.getX(); switch (action) { case MotionEvent.ACTION_DOWN: /* * If being flinged and user touches, stop the fling. isFinished * will be false if being flinged. */ if (!mScroller.isFinished()) { mScroller.abortAnimation(); } // Remember where the motion event started mLastMotionX = x; mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; if(handler!=null) handler.removeMessages(0); break; case MotionEvent.ACTION_MOVE: final int xDiff = (int) Math.abs(x - mLastMotionX); boolean xMoved = xDiff > mTouchSlop; if (xMoved) { // Scroll if the user moved far enough along the X axis mTouchState = TOUCH_STATE_SCROLLING; } if (mTouchState == TOUCH_STATE_SCROLLING) { // Scroll to follow the motion event final int deltaX = (int) (mLastMotionX - x); mLastMotionX = x; final int scrollX = getScrollX(); if (deltaX < 0) { if (scrollX > 0) { scrollBy(Math.max(-scrollX, deltaX), 0); } } else if (deltaX > 0) { final int availableToScroll = getChildAt( getChildCount() - 1).getRight() - scrollX - getWidth(); if (availableToScroll > 0) { scrollBy(Math.min(availableToScroll, deltaX), 0); } } return true; } break; case MotionEvent.ACTION_UP: if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); int velocityX = (int) velocityTracker.getXVelocity(); if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) { // Fling hard enough to move left snapToScreen(mCurrentScreen - 1); } else if (velocityX < -SNAP_VELOCITY && mCurrentScreen < getChildCount() - 1) { // Fling hard enough to move right snapToScreen(mCurrentScreen + 1); } else { snapToDestination(); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } mTouchState = TOUCH_STATE_REST; if(handler!=null){ Message message = handler.obtainMessage(0); handler.sendMessageDelayed(message, timeSpan); } break; case MotionEvent.ACTION_CANCEL: mTouchState = TOUCH_STATE_REST; } return false; } @Override public boolean onTouchEvent(MotionEvent ev) { if(mSideBuffer<2){ return false; } if (getChildCount() == 0) return false; if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); final int action = ev.getAction(); final float x = ev.getX(); switch (action) { case MotionEvent.ACTION_DOWN: /* * If being flinged and user touches, stop the fling. isFinished * will be false if being flinged. */ if (!mScroller.isFinished()) { mScroller.abortAnimation(); } // Remember where the motion event started mLastMotionX = x; mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; if(handler!=null) handler.removeMessages(0); break; case MotionEvent.ACTION_MOVE: final int xDiff = (int) Math.abs(x - mLastMotionX); boolean xMoved = xDiff > mTouchSlop; if (xMoved) { // Scroll if the user moved far enough along the X axis mTouchState = TOUCH_STATE_SCROLLING; } if (mTouchState == TOUCH_STATE_SCROLLING) { // Scroll to follow the motion event final int deltaX = (int) (mLastMotionX - x); mLastMotionX = x; final int scrollX = getScrollX(); if (deltaX < 0) { if (scrollX > 0) { scrollBy(Math.max(-scrollX, deltaX), 0); } } else if (deltaX > 0) { final int availableToScroll = getChildAt( getChildCount() - 1).getRight() - scrollX - getWidth(); if (availableToScroll > 0) { scrollBy(Math.min(availableToScroll, deltaX), 0); } } return true; } break; case MotionEvent.ACTION_UP: if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); int velocityX = (int) velocityTracker.getXVelocity(); if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) { // Fling hard enough to move left snapToScreen(mCurrentScreen - 1); } else if (velocityX < -SNAP_VELOCITY && mCurrentScreen < getChildCount() - 1) { // Fling hard enough to move right snapToScreen(mCurrentScreen + 1); }// else if (velocityX < -SNAP_VELOCITY// && mCurrentScreen == getChildCount() - 1) {// snapToScreen(0);// }// else if (velocityX > SNAP_VELOCITY// && mCurrentScreen == 0) {// snapToScreen(getChildCount() - 1);// } else { snapToDestination(); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } mTouchState = TOUCH_STATE_REST; if(handler!=null){ Message message = handler.obtainMessage(0); handler.sendMessageDelayed(message, timeSpan); } break; case MotionEvent.ACTION_CANCEL: snapToDestination(); mTouchState = TOUCH_STATE_REST; } return true; } @Override protected void onScrollChanged(int h, int v, int oldh, int oldv) { super.onScrollChanged(h, v, oldh, oldv); if (mIndicator != null) { /* * The actual horizontal scroll origin does typically not match the * perceived one. Therefore, we need to calculate the perceived * horizontal scroll origin here, since we use a view buffer. */ int hPerceived = h + (mCurrentAdapterIndex - mCurrentBufferIndex) * getWidth(); mIndicator.onScrolled(hPerceived, v, oldh, oldv); } } private void snapToDestination() { final int screenWidth = getWidth(); final int whichScreen = (getScrollX() + (screenWidth / 2)) / screenWidth; snapToScreen(whichScreen); } private void snapToScreen(int whichScreen) { mLastScrollDirection = whichScreen - mCurrentScreen; if (!mScroller.isFinished()) return; whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1)); mNextScreen = whichScreen; final int newX = whichScreen * getWidth(); final int delta = newX - getScrollX(); mScroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 2); invalidate(); } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { scrollTo(mScroller.getCurrX(), mScroller.getCurrY()); postInvalidate(); } else if (mNextScreen != INVALID_SCREEN) { mCurrentScreen = Math.max(0, Math.min(mNextScreen, getChildCount() - 1)); mNextScreen = INVALID_SCREEN; postViewSwitched(mLastScrollDirection); } } /** * Scroll to the {@link View} in the view buffer specified by the index. * * @param indexInBuffer * Index of the view in the view buffer. */ private void setVisibleView(int indexInBuffer, boolean uiThread) { mCurrentScreen = Math.max(0, Math.min(indexInBuffer, getChildCount() - 1)); int dx = (mCurrentScreen * getWidth()) - mScroller.getCurrX(); mScroller.startScroll(mScroller.getCurrX(), mScroller.getCurrY(), dx, 0, 0); if(dx == 0) onScrollChanged(mScroller.getCurrX() + dx, mScroller.getCurrY(), mScroller.getCurrX() + dx, mScroller.getCurrY()); if (uiThread) invalidate(); else postInvalidate(); } /** * Set the listener that will receive notifications every time the {code * ViewFlow} scrolls. * * @param l * the scroll listener */ public void setOnViewSwitchListener(ViewSwitchListener l) { mViewSwitchListener = l; } @Override public Adapter getAdapter() { return mAdapter; } @Override public void setAdapter(Adapter adapter) { setAdapter(adapter, 0); } public void setAdapter(Adapter adapter, int initialPosition) { if (mAdapter != null) { mAdapter.unregisterDataSetObserver(mDataSetObserver); } mAdapter = adapter; if (mAdapter != null) { mDataSetObserver = new AdapterDataSetObserver(); mAdapter.registerDataSetObserver(mDataSetObserver); } if (mAdapter == null || mAdapter.getCount() == 0) return; setSelection(initialPosition); } @Override public View getSelectedView() { return (mCurrentBufferIndex < mLoadedViews.size() ? mLoadedViews .get(mCurrentBufferIndex) : null); } @Override public int getSelectedItemPosition() { return mCurrentAdapterIndex; } /** * Set the FlowIndicator * * @param flowIndicator */ public void setFlowIndicator(FlowIndicator flowIndicator) { mIndicator = flowIndicator; mIndicator.setViewFlow(this); } @Override public void setSelection(int position) { mNextScreen = INVALID_SCREEN; mScroller.forceFinished(true); if (mAdapter == null) return; position = Math.max(position, 0); position = Math.min(position, mAdapter.getCount() - 1); ArrayList<View> recycleViews = new ArrayList<View>(); View recycleView; while (!mLoadedViews.isEmpty()) { recycleViews.add(recycleView = mLoadedViews.remove()); detachViewFromParent(recycleView); } View currentView = makeAndAddView(position, true, (recycleViews.isEmpty() ? null : recycleViews.remove(0))); mLoadedViews.addLast(currentView); for(int offset = 1; mSideBuffer - offset >= 0; offset++) { int leftIndex = position - offset; int rightIndex = position + offset; if(leftIndex >= 0) mLoadedViews.addFirst(makeAndAddView(leftIndex, false, (recycleViews.isEmpty() ? null : recycleViews.remove(0)))); if(rightIndex < mAdapter.getCount()) mLoadedViews.addLast(makeAndAddView(rightIndex, true, (recycleViews.isEmpty() ? null : recycleViews.remove(0)))); } mCurrentBufferIndex = mLoadedViews.indexOf(currentView); mCurrentAdapterIndex = position; for (View view : recycleViews) { removeDetachedView(view, false); } requestLayout(); setVisibleView(mCurrentBufferIndex, false); if (mIndicator != null) { mIndicator.onSwitched(mLoadedViews.get(mCurrentBufferIndex), mCurrentAdapterIndex); } if (mViewSwitchListener != null) { mViewSwitchListener .onSwitched(mLoadedViews.get(mCurrentBufferIndex), mCurrentAdapterIndex); } } private void resetFocus() { mLoadedViews.clear(); removeAllViewsInLayout(); for (int i = Math.max(0, mCurrentAdapterIndex - mSideBuffer); i < Math .min(mAdapter.getCount(), mCurrentAdapterIndex + mSideBuffer + 1); i++) { mLoadedViews.addLast(makeAndAddView(i, true, null)); if (i == mCurrentAdapterIndex) mCurrentBufferIndex = mLoadedViews.size() - 1; } requestLayout(); } private void postViewSwitched(int direction) { if (direction == 0) return; if (direction > 0) { // to the right mCurrentAdapterIndex++; mCurrentBufferIndex++;// if(direction > 1) {// mCurrentAdapterIndex += mAdapter.getCount() - 2;// mCurrentBufferIndex += mAdapter.getCount() - 2;// } View recycleView = null; // Remove view outside buffer range if (mCurrentAdapterIndex > mSideBuffer) { recycleView = mLoadedViews.removeFirst(); detachViewFromParent(recycleView); // removeView(recycleView); mCurrentBufferIndex--; } // Add new view to buffer int newBufferIndex = mCurrentAdapterIndex + mSideBuffer; if (newBufferIndex < mAdapter.getCount()) mLoadedViews.addLast(makeAndAddView(newBufferIndex, true, recycleView)); } else { // to the left mCurrentAdapterIndex--; mCurrentBufferIndex--;// if(direction < -1) {// mCurrentAdapterIndex -= mAdapter.getCount() - 2;// mCurrentBufferIndex -= mAdapter.getCount() - 2;// } View recycleView = null; // Remove view outside buffer range if (mAdapter.getCount() - 1 - mCurrentAdapterIndex > mSideBuffer) { recycleView = mLoadedViews.removeLast(); detachViewFromParent(recycleView); } // Add new view to buffer int newBufferIndex = mCurrentAdapterIndex - mSideBuffer; if (newBufferIndex > -1) { mLoadedViews.addFirst(makeAndAddView(newBufferIndex, false, recycleView)); mCurrentBufferIndex++; } } requestLayout(); setVisibleView(mCurrentBufferIndex, true); if (mIndicator != null) { mIndicator.onSwitched(mLoadedViews.get(mCurrentBufferIndex), mCurrentAdapterIndex); } if (mViewSwitchListener != null) { mViewSwitchListener .onSwitched(mLoadedViews.get(mCurrentBufferIndex), mCurrentAdapterIndex); } } private View setupChild(View child, boolean addToEnd, boolean recycle) { LayoutParams p = (LayoutParams) child .getLayoutParams(); if (p == null) { p = new AbsListView.LayoutParams( LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT, 0); } if (recycle) attachViewToParent(child, (addToEnd ? -1 : 0), p); else addViewInLayout(child, (addToEnd ? -1 : 0), p, true); return child; } private View makeAndAddView(int position, boolean addToEnd, View convertView) { View view = mAdapter.getView(position, convertView, this); return setupChild(view, addToEnd, convertView != null); } class AdapterDataSetObserver extends DataSetObserver { @Override public void onChanged() { View v = getChildAt(mCurrentBufferIndex); if (v != null) { for (int index = 0; index < mAdapter.getCount(); index++) { if (v.equals(mAdapter.getItem(index))) { mCurrentAdapterIndex = index; break; } } } resetFocus(); } @Override public void onInvalidated() { // Not yet implemented! } } public void setTimeSpan(long timeSpan) { this.timeSpan = timeSpan; } public void setmSideBuffer(int mSideBuffer) { this.mSideBuffer = mSideBuffer; }}上面这三个view就是对轮播图片的逻辑的封装,如果只想用的小伙伴就可以不看了，复制粘贴，改下包名ok
MainActivity
package com.example.bannerdemo;import java.util.ArrayList;import java.util.List;import com.nostra13.universalimageloader.core.ImageLoader;import android.app.Activity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;public class MainActivity extends Activity {private ViewFlow viewFlow;private CircleFlowIndicator viewflowindic;private List<Banner > list = new ArrayList<Banner>();String img0 = "http://121.42.220.158:8081/pinke/fileUpload/brannerImages/1451550226031.png";String img1 = "http://121.42.220.158:8081/pinke/fileUpload/brannerImages/1451550217854.png"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); init(); list.add(new Banner(img0)); list.add(new Banner(img1)); setupViewflow(list); } private void init() { viewFlow = (ViewFlow) findViewById(R.id.viewFlow); viewflowindic = (CircleFlowIndicator) findViewById(R.id.viewflowindic); } /** * 设置ViewFlow 轮播图片 */ private void setupViewflow(List<Banner> bannerList) { BannerAdapter bannerAdapter = new BannerAdapter(this, bannerList); viewFlow.setmSideBuffer(bannerList == null ? 0 : bannerList.size()); viewFlow.setSelection(0);//初始位置设置 viewflowindic.setVisibility(View.GONE); if (bannerList != null && bannerList.size() > 1) { viewflowindic.setVisibility(View.VISIBLE); viewFlow.setFlowIndicator(viewflowindic); viewFlow.startAutoFlowTimer(); // 启动自动播放 } else { viewFlow.stopAutoFlowTimer(); } viewFlow.setAdapter(bannerAdapter); }}BannerAdapter
package com.example.bannerdemo;import android.content.Context;import android.content.Intent;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import java.util.List;import com.nostra13.universalimageloader.core.DisplayImageOptions;import com.nostra13.universalimageloader.core.ImageLoader;import com.nostra13.universalimageloader.core.display.RoundedBitmapDisplayer;/** * * 图片轮播适配器 */public class BannerAdapter extends BaseAdapter{ private Context mContext; private List<Banner> bannerList; private LayoutInflater mInflater; DisplayImageOptions options; // DisplayImageOptions是用于设置图片显示的类 public BannerAdapter(Context mContext,List<Banner> bannerList){ this.mContext=mContext; this.bannerList=bannerList; mInflater=LayoutInflater.from(mContext); // 使用DisplayImageOptions.Builder()创建DisplayImageOptions options = new DisplayImageOptions.Builder() .showStubImage(R.drawable.ic_launcher) // 设置图片下载期间显示的图片 .showImageForEmptyUri(R.drawable.ic_launcher) // 设置图片Uri为空或是错误的时候显示的图片 .showImageOnFail(R.drawable.ic_launcher) // 设置图片加载或解码过程中发生错误显示的图片 .cacheInMemory(true) // 设置下载的图片是否缓存在内存中 .cacheOnDisc(true) // 设置下载的图片是否缓存在SD卡中 // .displayer(new RoundedBitmapDisplayer(20)) // 设置成圆角图片 .build(); // 创建配置过得DisplayImageOption对象 } @Override public int getCount() { return Integer.MAX_VALUE;//返回很大的值使得getview中的position不断增大来实现循环 } @Override public Object getItem(int position) { return position; } @Override public long getItemId(int position) { return position; } @Override public View getView(final int position, View convertView, ViewGroup parent){ ViewHolder mHolder=null; if(convertView==null){ mHolder=new ViewHolder(); convertView=mInflater.inflate(R.layout.item_banner,null); mHolder.imageView=(ImageView)convertView.findViewById(R.id.iv_banner); convertView.setTag(mHolder); }else{ mHolder=(ViewHolder)convertView.getTag(); } //因为返回的是最大值所以要取余得当当前循环后的item final Banner banner=bannerList.get(position % bannerList.size()); ImageLoader.getInstance().displayImage(banner.pic_url, mHolder.imageView,options); mHolder.imageView.setOnClickListener(new View.OnClickListener(){ @Override public void onClick(View v) { // 跳转 } }); return convertView; } class ViewHolder{ ImageView imageView; }}Banner实体类
package com.example.bannerdemo;/** * banner图片 */public class Banner { public String pic_url;//uil public Banner(String pic_url) { super(); this.pic_url = pic_url; } public Banner() { super(); }}加载图片的时候用的ImagerLoader框架，如果还需要导入ImagerLoader.jar
然后记得在application中初始化并在清单文件中添加权限：
package com.example.bannerdemo;import com.nostra13.universalimageloader.cache.disc.naming.Md5FileNameGenerator;import com.nostra13.universalimageloader.cache.memory.impl.UsingFreqLimitedMemoryCache;import com.nostra13.universalimageloader.core.DisplayImageOptions;import com.nostra13.universalimageloader.core.ImageLoader;import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;import com.nostra13.universalimageloader.core.assist.QueueProcessingType;import com.nostra13.universalimageloader.core.download.BaseImageDownloader;import android.app.Application;import android.graphics.Bitmap.CompressFormat;public class MyApplication extends Application { @SuppressWarnings("deprecation") @Override public void onCreate() { super.onCreate(); ImageLoaderConfiguration config = new ImageLoaderConfiguration .Builder(this) .memoryCacheExtraOptions(480, 800) // max width, max height，即保存的每个缓存文件的最大长宽 .threadPoolSize(3)//线程池内加载的数量 .threadPriority(Thread.NORM_PRIORITY - 2) .denyCacheImageMultipleSizesInMemory() .memoryCache(new UsingFreqLimitedMemoryCache(2 * 1024 * 1024)) // You can pass your own memory cache implementation/你可以通过自己的内存缓存实现 .memoryCacheSize(2 * 1024 * 1024) .discCacheSize(50 * 1024 * 1024) .discCacheFileNameGenerator(new Md5FileNameGenerator())//将保存的时候的URI名称用MD5 加密 .tasksProcessingOrder(QueueProcessingType.LIFO) .defaultDisplayImageOptions(DisplayImageOptions.createSimple()) .imageDownloader(new BaseImageDownloader(this, 5 * 1000, 30 * 1000)) // connectTimeout (5 s), readTimeout (30 s)超时时间 .writeDebugLogs() // Remove for release app .build();//开始构建 //Initialize ImageLoader with configuration. ImageLoader.getInstance().init(config); } } <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 下面在附加这个项目中用到的一些资源：
atrrs.xml
<?xml version="1.0" encoding="utf-8"?><resources> <declare-styleable name="ViewFlow"> <attr name="sidebuffer" format="integer"/> </declare-styleable> <declare-styleable name="CircleFlowIndicator"> <attr name="activeColor" format="color" /> <attr name="inactiveColor" format="color" /> <attr name="radius" format="dimension" /> <attr name="centered" format="boolean" /> <attr name="fadeOut" format="integer" /> <attr name="inactiveType"> <flag name="stroke" value="0" /> <flag name="fill" value="1" /> </attr> <attr name="activeType"> <flag name="stroke" value="0" /> <flag name="fill" value="1" /> </attr> <attr name="circleSeparation" format="dimension" /> <attr name="activeRadius" format="dimension" /> </declare-styleable></resources>item_banner.xml
<?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:orientation="vertical"> <ImageView android:id="@+id/iv_banner" android:layout_width="match_parent" android:layout_height="match_parent" android:scaleType="fitXY" /></LinearLayout>activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" xmlns:banner="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" > <RelativeLayout android:id="@+id/rl_banner" android:layout_width="match_parent" android:layout_height="150dp" android:layout_marginTop="20dp"> <com.example.bannerdemo.ViewFlow android:id="@+id/viewFlow" android:layout_width="match_parent" android:layout_height="match_parent" /> <com.example.bannerdemo.CircleFlowIndicator android:id="@+id/viewflowindic" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:layout_marginBottom="8dp" android:visibility="gone" banner:activeColor="#8000b5ff" banner:activeType="fill" banner:circleSeparation="15dip" banner:inactiveColor="#80ffffff" banner:inactiveType="fill" banner:radius="3dip" /> </RelativeLayout></RelativeLayout>代码看起来比较多，如果直接继承viewper的话不需要写这么多，但是实际上用到的代码就是MainActivity中的setupViewflow(),需要注意的是adapter中的getCount()的处理！ok，这个基本上就说完了！
附上项目下载地址eclipse版的
http://download.csdn.net/detail/wei8023hzp/9408230
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