Android 使用ViewPager实现轮播图效果
时间：2021-02-07 14:46:16|栏目：Android代码|点击： 次
写这篇文章只是对今天所学的知识进行加深印象，对ViewPager的一些处理，比如适配器和各个方法的作用等。
先看效果图
这里我是在xml中写的圆点
Drawable文件夹下的xml代码：
Shape_yes.xml:
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android"> <solid android:color="#ff6c67"></solid> <corners android:radius="1000dp"></corners> </shape>
Shape_no.xml:
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android"> <solid android:color="#f0f0f0"></solid> <corners android:radius="1000dp"></corners> </shape>
选择器
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_no"
android:state_selected="false"
/>
<item android:drawable="@drawable/shape_yes"
android:state_selected="true"
/>
</selector>
Activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="160dp">
<android.support.v4.view.ViewPager
android:id="@+id/vp"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</android.support.v4.view.ViewPager>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_alignParentBottom="true"
android:gravity="center_horizontal"
android:padding="5dp"
android:orientation="vertical"
android:background="#66000000">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:gravity="center"
android:orientation="horizontal"
android:paddingBottom="10dp">
<ImageView
android:id="@+id/iv_one"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_marginRight="20dp"
android:background="@drawable/selector_show" />
<ImageView
android:id="@+id/iv_two"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_marginRight="20dp"
android:background="@drawable/selector_show" />
<ImageView
android:id="@+id/iv_three"
android:layout_width="20dp"
android:layout_height="20dp"
android:background="@drawable/selector_show" />
</LinearLayout>
</LinearLayout>
</RelativeLayout>
</RelativeLayout>
写一个类ViewPagerAdapter_Circleextends PagerAdapter
public class ViewPagerAdapter_Circle extends PagerAdapter {
ArrayList<View> arrayList;
Context context;
public ViewPagerAdapter_Circle(ArrayList<View> arrayList, Context context) {
this.arrayList = arrayList;
this.context = context;
}
/***数据源的大小（条目）*/
@Override
public int getCount() {
return arrayList.size();
}
/**
* 页面视图是否关联到特定的对象
*/
@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;//判断当前要显示的页面
}
/**
* 初始化页面
* 1.页面添加到container
* 2.将页面返回
*/
@Override
public Object instantiateItem(ViewGroup container, int position) {
container.addView(arrayList.get(position));//页面添加到container，添加位置
return arrayList.get(position);
}
/**
* 销毁当前页面
*/
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView(arrayList.get(position));
}
}
MainActivity中代码（含注解）
public class MainActivity extends AppCompatActivity {
ViewPager viewPager;
int imageResIds[];
ArrayList<View> imageViewList;//存图片的集合
ArrayList<ImageView> imageViews;//存白点的集合
ImageView iv_one,iv_two,iv_three;
int oldPostion;//记录原来的位置
private Boolean flag;
int count=0;
Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
if (msg.what == 0) {
viewPager.setCurrentItem(count);
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化布局
initView();
//初始化数据
initData();
//设置适配器
initAdapter();
//设置圆点
initPoint();
flag = true;
//循环设置播放
new Thread() {
@Override
public void run() {
while (flag) {
try {
Thread.sleep(3000);
count++;
if (count == 3) {
count = 0;
}
} catch (InterruptedException e) {
e.printStackTrace();
}
/**传递信息*/
Message msg = new Message();
msg.what = 0;
msg.obj = count;
handler.sendMessage(msg);
}
}
}.start();
}
private void initView() {
viewPager = (ViewPager) findViewById(R.id.vp);
}
//初始化要显示的数据
private void initData() {
//图片资源数组
imageResIds = new int[]{R.mipmap.a, R.mipmap.b, R.mipmap.c};
imageViewList = new ArrayList<>();//存图片的集合
ImageView imageView;
for (int i = 0; i < imageResIds.length; i++) {
imageView = new ImageView(this);
imageView.setBackgroundResource(imageResIds[i]);
imageViewList.add(imageView);
}
}
//设置适配器
private void initAdapter() {
ViewPagerAdapter_Circle myViewPagerAdapter = new ViewPagerAdapter_Circle(imageViewList, this);
viewPager.setAdapter(myViewPagerAdapter);
}
/**
* 设置圆点的
*/
private void initPoint() {
iv_one = (ImageView) findViewById(R.id.iv_one);
iv_two = (ImageView) findViewById(R.id.iv_two);
iv_three = (ImageView) findViewById(R.id.iv_three);
imageViews = new ArrayList<>();
imageViews.add(iv_one);
imageViews.add(iv_two);
imageViews.add(iv_three);
iv_one.setSelected(true);//设置第一个圆点为true
/**viewPager监听事件*/
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
/**滑动时调用*/
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
/**停止时调用*/
@Override
public void onPageSelected(int position) {
imageViews.get(position).setSelected(true);//滑动后颜色改变
imageViews.get(oldPostion).setSelected(false);//变为初始颜色
oldPostion = position;//把滑动后的圆点的position给原来的oldPostion
}
/**滑动状态改变时调用*/
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
}
