ViewPager：
是Android3.0以后出来的一个控件，支持页面的左右滑动。是一个容器，需要通过适配器来完成相应的操作。
ViewPager的事件监听：
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int i, float v, int i1) {
//滚动完成之后调用
}
@Override
public void onPageSelected(int i) {
//页面改变调用
}
@Override
public void onPageScrollStateChanged(int i) {
//页面状态改变之后调用
}
});
滚动控件的适配器：PagerAdapter、FragmentPagerAdapter(是特制给Fragment的适配器，v4包提供，Fragment必须也是v4包才能匹配)
自定义的PagerAdapter如下：
public class MyPagerAdapter extends PagerAdapter {
List<View> views = new ArrayList<>();
public MyPagerAdapter(List<View> views) {
this.views = views;
}
@Override
public int getCount() {
return views.size();
}
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
return false;
}
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
View v = views.get(position);
if (v.getParent() != null) {
ViewGroup vg = (ViewGroup) v.getParent();
vg.removeView(v);
}
container.removeView(v);
container.addView(v);
return v;
}
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
super.destroyItem(container, position, object);
container.removeView(views.get(position));
}
}
ViewPager实现图片广告的自动和手动切换
- 初始化数据
public void initData(){
for (int i = 0; i < titles.length; i++) {
ImageView img = new ImageView(this);
img.setBackgroundResource(imgs[i]); //不设置src而是设置background，为了让图片充满
img.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.MATCH_PARENT));
listImg.add(img); //将需要显示的view装进容器里面
View view = new View(this); //初始化指示器的小白点的view
view.setBackgroundResource(R.drawable.dot_normal); //设置小白点的背景
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(25, 25);
params.setMargins(20,25,0,0); //设置View外边距
view.setLayoutParams(params);
selectedContainer.addView(view);
points.add(view);
}
mTextView.setText(titles[0]);
points.get(0).setBackgroundResource(R.drawable.dot_enable);
}
- 设置适配器,一般这种简单的自定义适配器，使用内部类完成
private void setAdapter() {
MyPagerAdapter myPagerAdapter = new MyPagerAdapter(listImg);
mViewPager.setAdapter(myPagerAdapter);
}
public class MyPagerAdapter extends PagerAdapter {
List<View> views = new ArrayList<>();
public MyPagerAdapter(List<View> views) {
this.views = views;
}
@Override
public int getCount() {
return views.size();
}
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
return view == o;
}
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
View v = views.get(position % views.size());
if (v.getParent() != null) {
ViewGroup vg = (ViewGroup) v.getParent();
vg.removeView(v);
}
container.removeView(v);
container.addView(v);
return v;
}
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
super.destroyItem(container, position, object);
container.removeView(views.get(position % views.size()));
}
}
- 设置页面改变的监听事件
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int i, float v, int i1) {
}
@Override
public void onPageSelected(int i) {
mTextView.setText(titles[i / listImg.size()]);
points.get(prePosition).setBackgroundResource(R.drawable.dot_normal);
points.get(i / listImg.size()).setBackgroundResource(R.drawable.dot_enable);
//记录的是改变之前的位置
prePosition = i % listImg.size();
}
@Override
public void onPageScrollStateChanged(int i) {
}
});
- 设置自动切换
public void enableAutoFling() {
new Thread(new Runnable() {
@Override
public void run() {
while (isLooping){
try {
Thread.sleep(3000);
mHandler.sendEmptyMessage(100); //通过handler传递消息到主线程
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
}
Handler mHandler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what){
case 100:
//获取viewpager当前的位置
int position = mViewPager.getCurrentItem();
//向下一个页面进行滑动
mViewPager.setCurrentItem(position+1);
break;
}
}
};
ViewPager+Fragment的联动使用
- 初始化数据
public void initData(){
for (int i = 0; i < 4; i++) {
ContentFragment mContentFragment = new ContentFragment();
Bundle bundle = new Bundle();
bundle.putString("content","页面 "+i);
mContentFragment.setArguments(bundle); // 将数据传递给Fragment
fragments.add(mContentFragment);
}
}
在Fragment中的onActivityCreated方法中接收传递过来的数据
String result = getArguments().getString("content");
mTextView.setText(result);
- 设置适配器
private void setAdapter() {
MyFragmentPagerAdapter myFragmentPagerAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(myFragmentPagerAdapter);
}
/**
* 自定义适配器，适配ViewPage和Fragment.这种简单的适配器，一般都定义内部类，这样可以共享全局资源。
*/
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
MyFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int i) {
return fragments.get(i);
}
@Override
public int getCount() {
return fragments.size();
}
}
好了，ViewPage和Fragment的简单联动就回顾到这里了，下一篇我会写一个实际的demo来讲解稍复杂一点的情况。喜欢的朋友可以先点个赞哦。收藏一下。
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