Android实现导航页之一动态显示页面下小点

一、创建项目；

二、创建第二个导航页面activity_guide

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;

import java.util.ArrayList;

public class activity_guide extends AppCompatActivity{

    private ViewPager guide_ViewPager;
    private VpAdapter vpAdapter;
    private static int[] imgs = {R.drawable.a, R.drawable.b, R.drawable.c};
    private ArrayList<ImageView> imageViews;
    private ImageView[] dotViews;//小圆点
    private VpAdapter adapter;
    private LinearLayout dot_Layout;
    private ViewPager vp;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_guide);
        initView();


    }

    private void initView() {
        dot_Layout = (LinearLayout) findViewById(R.id.dot_Layout);
        initImages();
        initDots();
        vp = (ViewPager) findViewById(R.id.vp);

        vpAdapter=new VpAdapter(imageViews);
        vp.setAdapter(vpAdapter);
        vp.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                for(int i = 0; i < dotViews.length; i++) {
                    if (position == i) {
                        dotViews[i].setSelected(true);
                    } else {
                        dotViews[i].setSelected(false);
                    }
                }
                }
            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    private void initDots() {
        LinearLayout layout = (LinearLayout) findViewById(R.id.dot_Layout);
        LinearLayout.LayoutParams mParams = new LinearLayout.LayoutParams(20, 20);
        mParams.setMargins(10, 0, 10, 0);//设置小圆点左右之间的间隔
        dotViews = new ImageView[imgs.length];
        //判断小圆点的数量，从0开始，0表示第一个
        for (int i = 0; i < imageViews.size(); i++) {
            ImageView imageView = new ImageView(this);
            imageView.setLayoutParams(mParams);
            imageView.setImageResource(R.drawable.asd);
            if (i == 0) {
                imageView.setSelected(true);//默认启动时，选中第一个小圆点
            } else{
                imageView.setSelected(false);
            }


            dotViews[i] = imageView;//得到每个小圆点的引用，用于滑动页面时，（onPageSelected方法中）更改它们的状态。
            layout.addView(imageView);//添加到布局里面显示
        }

    }


    private void initImages() {
        //设置每一张图片都填充窗口
        ViewPager.LayoutParams mParams = new ViewPager.LayoutParams();
        imageViews = new ArrayList<ImageView>();

        for (int i = 0; i < imgs.length; i++) {
            ImageView iv = new ImageView(this);
            iv.setLayoutParams(mParams);//设置布局
            iv.setImageResource(imgs[i]);//为ImageView添加图片资源
            iv.setScaleType(ImageView.ScaleType.FIT_XY);//这里也是一个图片的适配
            imageViews.add(iv);
            if (i == imgs.length - 1) {
                //为最后一张图片添加点击事件
                iv.setOnTouchListener(new View.OnTouchListener() {
                    @Override
                    public boolean onTouch(View v, MotionEvent event) {

                        Intent toMainActivity = new Intent(activity_guide.this, MainActivity.class);//跳转到主界面
                        startActivity(toMainActivity);
                        return true;

                    }
                });
            }

        }


    }


}

三、创建适配器vpAdapter

import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import java.util.ArrayList;

public class VpAdapter  extends PagerAdapter {

    private ArrayList<ImageView> imageViews;

    public VpAdapter(ArrayList<ImageView> imageViews) {
        this.imageViews = imageViews;
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return imageViews.size();
    }

    /**
     * 判断是否用对象生成界面
     */
    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        // TODO Auto-generated method stub
        return arg0 == arg1;
    }

    /**
     * 从ViewGroup中移除当前对象（图片）
     */
    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView(imageViews.get(position));
    }

    /**
     * 当前要显示的对象（图片）
     */
    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        container.addView(imageViews.get(position));
        return imageViews.get(position);
    }

}

四、在drawable文件夹下创建xml文件asd.xml设置圆点颜色改变

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:drawable="@drawable/circle_grey1" android:state_selected="false"/>
    <item android:drawable="@drawable/circle_blu1e" android:state_selected="true"/>

五、修改mainfests.xml文件改到引导页启动页面

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.viewpagesp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">

        </activity>
        <activity android:name=".activity_guide"   >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity   >
    </application>

</manifest>

注释以下是需要的图片元素材料