Android开发之app基础---自动轮播图

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