本文实例为大家分享了Android自定义轮播图的具体代码，供大家参考，具体内容如下
定义Banner
主要使用ViewPager实现滑动
public class Banner extends FrameLayout {
public Context context;
private @LayoutRes
int layoutId = R.layout.banner_view;
private View inflate;
private ViewPager pager;
private AutoHandler mHandler;
private PagerAdapter adapter;
public IndicatorView indicatorView;
public Banner(@NonNull Context context) {
this(context, null);
}
public Banner(@NonNull Context context, @Nullable AttributeSet attrs) {
this(context, attrs, -1);
}
public Banner(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context, attrs, defStyleAttr);
}
public void setAdapter(PagerAdapter adapter) {
this.adapter = adapter;
pager.setAdapter(adapter);
indicatorView.setPager(pager);
}
private void init(Context context, AttributeSet attrs, int defStyleAttr) {
this.context = context;
inflate = LayoutInflater.from(context).inflate(layoutId, this, true);
pager = inflate.findViewById(R.id.banner_pager);
indicatorView = inflate.findViewById(R.id.indicatorView);
mHandler = new AutoHandler(pager);
mHandler.start();
}
public abstract static class BannerAdapter extends PagerAdapter {
private List list;
private Context context;
public BannerAdapter(List list, Context context) {
this.list = list;
this.context = context;
}
@Override
public int getCount() {
if (null == list || list.size() == 0) {
return 1;
} else {
return list.size();
}
}
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
return view == object;
}
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
if (getLayout() > 0) {
View inflate = LayoutInflater.from(context).inflate(getLayout(), container, false);
container.addView(inflate);
setView(inflate, position);
return inflate;
} else {
ImageView imageView = new ImageView(context);
container.addView(imageView);
if (list.size() > 0) {
Glide.with(context).load(list.get(position))
.apply(new RequestOptions().centerCrop())
.into(imageView);
} else {
// Glide.with(context)
// .load(R.mipmap.ic_launcher)
// .apply(new RequestOptions().centerCrop())
// .into(imageView);
imageView.setBackgroundResource(R.mipmap.ic_launcher);
}
return imageView;
}
}
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
container.removeView((View) object);
}
protected abstract void setView(View inflate, int position);
protected abstract int getLayout();
}
}
定义定时器Handler
主要处理ViewPager的滚动 开启定时任务 ViewPager自动滚动
public class AutoHandler extends Handler {
private ViewPager pager;
public static int TIME = 1000 * 2;
public boolean stopHandler;
public AutoHandler(ViewPager pager) {
this.pager = pager;
}
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 100:
if (!stopHandler) {
sendEmptyMessageDelayed(100, TIME);
int position = pager.getCurrentItem() + 1;
if (position >= pager.getAdapter().getCount()) {
position = 0;
}
pager.setCurrentItem(position);
} else {
removeMessages(100);
}
break;
default:
removeMessages(100);
break;
}
}
public void start() {
stopHandler = false;
if (!hasMessages(100)) {
sendEmptyMessageDelayed(100, TIME);
}
}
public void stop() {
stopHandler = true;
if (hasMessages(100)) {
removeMessages(100);
}
}
}
绘制一个下标指示器
主要根据需求自行绘制 可有可无 和ViewPager关联在一起 实现联动
public class IndicatorView extends View {
private Context context;
private ValueAnimator valueAnimator;
private float value;
public int indiWidth;
public int indiHeight;
public int indiDivide;
//0圆角 1直角
public int mode;
private int normalColor;
private int selectColor;
private int curPosition;
private int count;
private Paint paint;
private int width;
private int height;
private double lastPosition;
private ViewPager pager;
private PagerAdapter adapter;
private DataSetObserver dataSetObserver;
public void setPager(final ViewPager pager) {
this.pager = pager;
this.adapter = pager.getAdapter();
dataSetObserver = new DataSetObserver() {
@Override
public void onChanged() {
super.onChanged();
setCount(adapter.getCount());
setCurPosition(pager.getCurrentItem());
}
};
if (null != adapter) {
setCount(adapter.getCount());
setCurPosition(pager.getCurrentItem());
adapter.registerDataSetObserver(dataSetObserver);
}
pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
lastPosition = position;
}
@Override
public void onPageSelected(int position) {
curPosition = position;
setCurPosition(position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
pager.addOnAdapterChangeListener(new ViewPager.OnAdapterChangeListener() {
@Override
public void onAdapterChanged(@NonNull ViewPager viewPager, @Nullable PagerAdapter oldAdapter, @Nullable PagerAdapter newAdapter) {
if (oldAdapter != newAdapter) {
adapter = newAdapter;
setCount(adapter.getCount());
setCurPosition(viewPager.getCurrentItem());
}
}
});
}
public void setCount(int count) {
this.count = count;
if (count <= 1) {
setVisibility(INVISIBLE);
}
requestLayout();
postInvalidate();
}
public void setCurPosition(int curPos) {
/*记录上次记录*/
//lastPos = this.curPos;
this.curPosition = curPos;
//postInvalidate();
valueAnimator.start();
}
public IndicatorView(Context context) {
this(context, null);
}
public IndicatorView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, -1);
}
public IndicatorView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context, attrs, defStyleAttr);
}
private void init(Context context, AttributeSet attrs, int defStyleAttr) {
this.context = context;
valueAnimator = ValueAnimator.ofFloat(0, 1f);
valueAnimator.setDuration(200);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
value = (float) animation.getAnimatedValue();
postInvalidate();
}
});
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.IndicatorView);
indiHeight = (int) typedArray.getDimension(R.styleable.IndicatorView_indi_height, getResources().getDimension(R.dimen.dp4));
indiWidth = (int) typedArray.getDimension(R.styleable.IndicatorView_indi_width, getResources().getDimension(R.dimen.dp4));
indiDivide = (int) typedArray.getDimension(R.styleable.IndicatorView_indi_divier, getResources().getDimension(R.dimen.dp4));
normalColor = typedArray.getColor(R.styleable.IndicatorView_indi_color, Color.parseColor("#66dddddd"));
selectColor = typedArray.getColor(R.styleable.IndicatorView_indi_color_select, Color.parseColor("#eedddddd"));
mode = typedArray.getInteger(R.styleable.IndicatorView_indi_mode, 0);
curPosition = 0;
count = 0;
paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(normalColor);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
width = indiWidth * count + (count - 1) * indiDivide;//每个的宽度加上中间间距的宽度
height = indiHeight;
setMeasuredDimension(width, height);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (int i = 0; i < count; i++) {
int x = i * (indiDivide + indiWidth);
if (mode == 0) {
paint.setColor(normalColor);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
canvas.drawRoundRect(x, 0, x + indiWidth, indiHeight, indiHeight / 2, indiHeight / 2, paint);
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
if (curPosition == i) {
paint.setColor(selectColor);
if (curPosition > lastPosition) {
canvas.drawRoundRect(x, 0, x + value * indiWidth, indiHeight, indiHeight / 2, indiHeight / 2, paint);
} else {
canvas.drawRoundRect(x + (1 - value) * indiWidth, 0, x + indiWidth, indiHeight, indiHeight / 2, indiHeight / 2, paint);
}
}
}
if (mode == 1) {
paint.setColor(normalColor);
canvas.drawRect(x, 0, x + indiWidth, indiHeight, paint);
if (curPosition == i) {
paint.setColor(selectColor);
if (curPosition > lastPosition) {
canvas.drawRect(x, 0, x + value * indiWidth, indiHeight, paint);
} else {
canvas.drawRect(x + (1 - value) * indiWidth, 0, x + indiWidth, indiHeight, paint);
}
}
}
}
}
}
}
在Activity中使用
banner.setAdapter(new Banner.BannerAdapter(strings, this) {
@Override
protected void setView(View inflate, int position) {
ImageView img = inflate.findViewById(R.id.img);
Glide.with(MainActivity.this).load(strings.get(position))
.apply(new RequestOptions().centerCrop())
.into(img);
}
@Override
protected int getLayout() {
return R.layout.img;
// return 0;
}
});
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
