<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:id="@+id/activity_main"android:layout_width="match_parent"android:layout_height="match_parent"tools:context="com.example.a2_.MainActivity"><android.support.v4.view.ViewPager  android:id="@+id/vp"  android:layout_width="match_parent"  android:layout_height="250dp"></android.support.v4.view.ViewPager><LinearLayout  android:orientation="vertical"  android:gravity="center"  android:background="#66000000"  android:layout_alignBottom="@id/vp"  android:layout_width="match_parent"  android:layout_height="50dp">  <TextView    android:id="@+id/desc"    android:text="描述文本"    android:textColor="#ffffff"    android:layout_width="wrap_content"    android:layout_height="wrap_content" />  <LinearLayout    android:id="@+id/layout_dot"    android:orientation="horizontal"    android:layout_width="wrap_content"    android:layout_height="wrap_content">  </LinearLayout></LinearLayout></RelativeLayout>

package com.example.a2_;import android.os.Handler;import android.os.Message;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.TextView;import java.util.ArrayList;public class MainActivity extends AppCompatActivity {private static final int UPDATE_ITEM = 1;private ArrayList<ImageView> imageViews = new ArrayList<>();private int[] imageResIds = {R.mipmap.icon_1, R.mipmap.icon_2, R.mipmap.icon_3,    R.mipmap.icon_4, R.mipmap.icon_5};private String[] descs = {"為夢想堅持", "我相信我是黑馬", "黑馬公開課", "Google/IO", "輕松1w+"};private ViewPager viewPager;private TextView tv_desc;private LinearLayout layout_dot;private int count = 10000000;private Handler handler = new Handler() {  @Override  public void handleMessage(Message msg) {    switch (msg.what) {      case UPDATE_ITEM:        upDataItem();        break;    }    super.handleMessage(msg);  }};@Overrideprotected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  //初始化控件  viewPager = (ViewPager) findViewById(R.id.vp);  tv_desc = (TextView) findViewById(R.id.desc);  layout_dot = (LinearLayout) findViewById(R.id.layout_dot);  //給viewPager設置適配器  viewPager.setAdapter(new MyPagerAdapter());  //對viewPager設置監(jiān)聽器  viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {    //當頁面滾動時觸發(fā)的時間    @Override    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {    }    //當頁面被選中時觸發(fā)的方法    @Override    public void onPageSelected(int position) {      //對position進行處理      position = position % imageViews.size();      //當頁面被選中的時候,改變描述文本      tv_desc.setText(descs[position]);      changeDots(position);    }    //當頁面狀態(tài)滾動狀態(tài)發(fā)生改變時觸發(fā)的事件    @Override    public void onPageScrollStateChanged(int state) {      //當頁面空閑狀態(tài)被改變的時候      if (state == viewPager.SCROLL_STATE_IDLE) {        handler.sendEmptyMessageDelayed(UPDATE_ITEM, 3000);      } else {        handler.removeMessages(UPDATE_ITEM);      }    }  });  //初始化圖片  initImage();  //初始化文字下方的點  initDot();  //當加載頁面的時候,默認讓第一個文本加載出來//    initDescFirst();  //使兩邊都可以無限輪播  viewPager.setCurrentItem(count / 2);//頁面加載時更新  upDataItem();}private void upDataItem() {  int index = viewPager.getCurrentItem();  viewPager.setCurrentItem(++index);  handler.sendEmptyMessageDelayed(UPDATE_ITEM, 3000);}//選中對應的原點private void changeDots(int position) {  //先把所有的點恢復為白色  for (int i = 0; i < layout_dot.getChildCount(); i++) {    View view = layout_dot.getChildAt(i);    view.setSelected(false);  }  //獲取當前被選中的條目 設置為選中狀態(tài)  layout_dot.getChildAt(position).setSelected(true);}//初始化文字下方的點private void initDot() {  LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(10, 10);  layoutParams.setMargins(4, 4, 4, 4);  for (int i = 0; i < imageViews.size(); i++) {    View view = new View(this);    view.setBackgroundResource(R.drawable.seletor_dot);    view.setLayoutParams(layoutParams);    layout_dot.addView(view);  }}//當加載頁面的時候,默認讓第一個文本加載出來private void initDescFirst() {  tv_desc.setText(descs[0]);  changeDots(0);}//添加圖片,準備一個ImageView集合,用來交給instantiateItem添加到頁面private void initImage() {  for (int i = 0; i < imageResIds.length; i++) {    //創(chuàng)建出ImageView對象    ImageView imageView = new ImageView(getApplicationContext());    imageView.setImageResource(imageResIds[i]);    imageViews.add(imageView);  }}private class MyPagerAdapter extends PagerAdapter {  @Override  public int getCount() {    return count;  }  @Override  public boolean isViewFromObject(View view, Object object) {    //判斷這個view是不是通過instantiateItem創(chuàng)建出來的    return view == object;  }  //用來創(chuàng)建條目  @Override  public Object instantiateItem(ViewGroup container, int position) {    position = position % imageResIds.length;    //獲取條目    ImageView imageView = imageViews.get(position);    container.addView(imageView);    return imageView;  }  //用來銷毀條目,,且最多會創(chuàng)建出三個條目,多出來的條目將會被銷毀  @Override  public void destroyItem(ViewGroup container, int position, Object object) {    //銷毀創(chuàng)建的條目    container.removeView((View) object);  }}@Overrideprotected void onStart() {  super.onStart();  //當頁面顯示的時候,更新輪播圖  handler.sendEmptyMessageDelayed(UPDATE_ITEM, 3000);}@Overrideprotected void onStop() {  super.onStop();  //當頁面不可見時,停止更新  handler.removeCallbacksAndMessages(null);}}