【ViewPager学习2】ViewPager入门以及实现APP引导页

原CSDN博客已弃用，文章会逐渐迁移过来。

一、最简单的ViewPager实现

(一)、创建可左右滑动的三个布局

view_first.xml

<?xml version="1.0" encoding="utf-8"?>  
<android.support.constraint.ConstraintLayout  
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"  
android:layout_height="match_parent">  

<TextView  
    android:textSize="20sp"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:text="first"/>  
</android.support.constraint.ConstraintLayout> 

view_second.xml

<?xml version="1.0" encoding="utf-8"?>  
<android.support.constraint.ConstraintLayout  
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"  
    android:layout_height="match_parent">  
    <TextView  
        android:textSize="20sp"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="second"/>  
</android.support.constraint.ConstraintLayout>  

view_thrid.xml

<?xml version="1.0" encoding="utf-8"?>  
<android.support.constraint.ConstraintLayout  
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"  
    android:layout_height="match_parent">  
    <TextView  
        android:textSize="20sp"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="thrid"/>  
</android.support.constraint.ConstraintLayout>  

(二)、activity_main.xml

<?xml version="1.0" encoding="utf-8"?>  
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:app="http://schemas.android.com/apk/res-auto"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    tools:context="com.administrator.viewpagerproject.MainActivity">  

    <android.support.v4.view.ViewPager  
        android:id="@+id/view_papger"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent">  
    </android.support.v4.view.ViewPager>  

</android.support.constraint.ConstraintLayout>  

(三)、MainActivity.java

package com.administrator.viewpagerproject;  

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 java.util.ArrayList;  
import java.util.List;  

public class MainActivity extends AppCompatActivity {  

    private ViewPager mViewPager;  
    private List<View> mViews;  

    /** 
     *一组视图 
     */  
    private int[] mLayoutIDs = {  
            R.layout.view_first,  
            R.layout.view_second,  
            R.layout.view_thrid};  
    private ImageView mImageView;  

    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        ViewPager mViewPager = findViewById(R.id.view_papger);  
        /** 
         * 一组视图放在列表里 
         */  
        //初始化数据  
        mViews = new ArrayList<>();  
        for (int i = 0; i < mLayoutIDs.length; i++) {  
            View view = getLayoutInflater().inflate(mLayoutIDs[i], null);  
            mViews.add(view);  
//            mImageView = new ImageView(this);  
//            mImageView.setImageResource(R.mipmap.ic_launcher);  
//            mViews.add(mImageView);  
        }  
        mViewPager.setAdapter(mPagerAdapter);//给Adapter  
    }  
    //设置Adapter  
    PagerAdapter mPagerAdapter = new PagerAdapter() {  
        @Override  
        public int getCount() {  
            return mLayoutIDs.length;  
        }  

        @Override  
        public boolean isViewFromObject(View view, Object object) {  
            return view == object;  
        }  

        //按顺序给页  
        @Override  
        public Object instantiateItem(ViewGroup container, int position) {  
            View child = mViews.get(position);  
            container.addView(child);  
            return child;  
        }  

        //按顺序销毁页  
        @Override  
        public void destroyItem(ViewGroup container, int position, Object object) {  
            container.removeView(mViews.get(position));  
        }  
    };  
}  

二、使用ViewPager实现App引导页

添加一张图片用于测试，图片名为diglett.png

可鼠标右键另存为保存这张测试图片

(一)、创建可左右滑动的三个布局

view_first.xml

<?xml version="1.0" encoding="utf-8"?>  
<android.support.constraint.ConstraintLayout  
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"  
    android:layout_height="match_parent">  

    <TextView  
        android:textSize="20sp"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="first"/>  
</android.support.constraint.ConstraintLayout>  

view_second.xml

<?xml version="1.0" encoding="utf-8"?>  
<android.support.constraint.ConstraintLayout  
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"  
    android:layout_height="match_parent">  
    <TextView  
        android:textSize="20sp"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="second"/>  
</android.support.constraint.ConstraintLayout>  

view_thrid.xml

<?xml version="1.0" encoding="utf-8"?>  
<android.support.constraint.ConstraintLayout  
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"  
    android:layout_height="match_parent">  
    <TextView  
        android:textSize="20sp"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="thrid"/>  
</android.support.constraint.ConstraintLayout>  

(二)、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">  

    <android.support.v4.view.ViewPager  
        android:id="@+id/view_papger"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent">  
    </android.support.v4.view.ViewPager>  
    <LinearLayout  
        android:id="@+id/dot_layout"  
        android:layout_width="120dp"  
        android:layout_height="30dp"  
        android:layout_alignParentBottom="true"  
        android:layout_centerHorizontal="true"  
        android:layout_marginBottom="30dp"  
        android:gravity="center"  
        android:orientation="horizontal">  

    </LinearLayout>  

</RelativeLayout>  

(三)、MainActivity.java

package com.administrator.viewpagerproject;  

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 java.util.ArrayList;  
import java.util.List;  

public class MainActivity extends AppCompatActivity {  

    private ViewPager mViewPager;  
    private List<View> mViews;  

    /** 
     *一组视图 
     */  
    private int[] mLayoutIDs = {  
            R.layout.view_first,  
            R.layout.view_second,  
            R.layout.view_thrid};  
    private ImageView mImageView;  

    private ViewGroup mDotViewGroup;  
    private List<ImageView> mDotViews = new ArrayList<>();  

    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        mViewPager = findViewById(R.id.view_papger);  
        mDotViewGroup = findViewById(R.id.dot_layout);  
        /** 
         * 一组视图放在列表里 
         */  
        //初始化数据  
        mViews = new ArrayList<>();  
        for (int i = 0; i < mLayoutIDs.length; i++) {  
            ImageView imageView = new ImageView(this);  
            imageView.setImageResource(R.mipmap.ic_launcher);  
            mViews.add(imageView);  

            ImageView dot = new ImageView(this);  
            dot.setImageResource(R.mipmap.ic_launcher);  
            dot.setMaxWidth(100);  
            dot.setMaxHeight(100);  

            LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(50,50);//相距50，50  
            layoutParams.leftMargin = 20;//每个点距离左边点20  
            dot.setLayoutParams(layoutParams);  
            dot.setEnabled(false);  

            mDotViewGroup.addView(dot);  
            mDotViews.add(dot);  
        }  
        //设置Adapter  
        mViewPager.setAdapter(mPagerAdapter);//给Adapter  
        mViewPager.setOffscreenPageLimit(4);//屏上的至少有几个  
        mViewPager.setCurrentItem(0);//控制最开始位置是第个布局，如：mViewPager.setCurrentItem(2);  
        setDotViews(0);//控制最开始位置是第几个点，如setDotViews(2);  
        mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {  
            @Override  
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {  
                //当它被滚动的时候  
            }  

            @Override  
            public void onPageSelected(int position) {  
                //当它被选中的时候  
                setDotViews(position);  

            }  

            @Override  
            public void onPageScrollStateChanged(int state) {  
                //当它滚动的状态变化的时候  
            }  
        });  

    }  

    public void setDotViews(int position) {  
        for (int index = 0; index < mDotViews.size() ; index++) {  
            mDotViews.get(index).setImageResource(position == index ? R.mipmap.diglett:R.mipmap.ic_launcher);  
        }  
    }  
    PagerAdapter mPagerAdapter = new PagerAdapter() {  
        @Override  
        public int getCount() {  
            return mLayoutIDs.length;  
        }  

        @Override  
        public boolean isViewFromObject(View view, Object object) {  
            return view == object;  
        }  

        //按顺序给页  
        @Override  
        public Object instantiateItem(ViewGroup container, int position) {  
            View child = mViews.get(position);  
            container.addView(child);  
            return child;  
        }  

        //按顺序销毁页  
        @Override  
        public void destroyItem(ViewGroup container, int position, Object object) {  
            container.removeView(mViews.get(position));  
        }  
    };  
}  

简单效果图：

三、较好用的引导页效果，滑动结束后点击按钮跳转

activity_guide.xml

<?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:layout_width="match_parent"  
    android:layout_height="match_parent"  
    tools:context="com.example.nanchen.guidepagedemo.GuideActivity">  

    <android.support.v4.view.ViewPager  
        android:id="@+id/guide_vp"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent">  
    </android.support.v4.view.ViewPager>  

    <LinearLayout  
        android:id="@+id/guide_ll_point"  
        android:layout_width="match_parent"  
        android:layout_height="wrap_content"  
        android:orientation="horizontal"  
        android:layout_alignParentBottom="true"  
        android:layout_marginBottom="40dp"  
        android:gravity="center_horizontal">  
    </LinearLayout>  

    <ImageButton  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:id="@+id/guide_ib_start"  
        android:src="@mipmap/btn_start"  
        android:layout_centerHorizontal="true"  
        android:layout_above="@+id/guide_ll_point"  
        android:background="@null"  
        android:visibility="gone"/>  
</RelativeLayout>  

GuidePagerAdapter.java

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

import java.util.List;  

/** 
 * Created by 南尘 on 2016/7/10. 
 */  
public class GuidePageAdapter extends PagerAdapter {  

    private List<View> viewList;  

    public GuidePageAdapter(List<View> viewList) {  
        this.viewList = viewList;  
    }  

    /** 
     * @return 返回页面的个数 
     */  
    @Override  
    public int getCount() {  
        if (viewList != null){  
            return viewList.size();  
        }  
        return 0;  
    }  

    /** 
     * 判断对象是否生成界面 
     * @param view 
     * @param object 
     * @return 
     */  
    @Override  
    public boolean isViewFromObject(View view, Object object) {  
        return view == object;  
    }  

    /** 
     * 初始化position位置的界面 
     * @param container 
     * @param position 
     * @return 
     */  
    @Override  
    public Object instantiateItem(ViewGroup container, int position) {  
        container.addView(viewList.get(position));  
        return viewList.get(position);  
    }  


    @Override  
    public void destroyItem(ViewGroup container, int position, Object object) {  
        container.removeView(viewList.get(position));  
    }  
}  

GuideActivity.java

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

import java.util.ArrayList;  
import java.util.List;  

/** 
 * 实现首次启动的引导页面 
 */  
public class GuideActivity extends AppCompatActivity implements ViewPager.OnPageChangeListener{  

    private ViewPager vp;  
    private int []imageIdArray;//图片资源的数组  
    private List<View> viewList;//图片资源的集合  
    private ViewGroup vg;//放置圆点  

    //实例化原点View  
    private ImageView iv_point;  
    private ImageView []ivPointArray;  

    //最后一页的按钮  
    private ImageButton ib_start;  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        supportRequestWindowFeature(Window.FEATURE_NO_TITLE);  
        setContentView(R.layout.activity_guide);  

        ib_start = (ImageButton) findViewById(R.id.guide_ib_start);  
        ib_start.setOnClickListener(new View.OnClickListener() {  
            @Override  
            public void onClick(View v) {  
                startActivity(new Intent(GuideActivity.this,MainActivity.class));  
                finish();  
            }  
        });  

        //加载ViewPager  
        initViewPager();  

        //加载底部圆点  
        initPoint();  
    }  

    /** 
     * 加载底部圆点 
     */  
    private void initPoint() {  
        //这里实例化LinearLayout  
        vg = (ViewGroup) findViewById(R.id.guide_ll_point);  
        //根据ViewPager的item数量实例化数组  
        ivPointArray = new ImageView[viewList.size()];  
        //循环新建底部圆点ImageView，将生成的ImageView保存到数组中  
        int size = viewList.size();  
        for (int i = 0;i<size;i++){  
            iv_point = new ImageView(this);  
            iv_point.setLayoutParams(new ViewGroup.LayoutParams(20,20));  
            iv_point.setPadding(30,0,30,0);//left,top,right,bottom  
            ivPointArray[i] = iv_point;  
            //第一个页面需要设置为选中状态，这里采用两张不同的图片  
            if (i == 0){  
                iv_point.setBackgroundResource(R.mipmap.full_holo);  
            }else{  
                iv_point.setBackgroundResource(R.mipmap.empty_holo);  
            }  
            //将数组中的ImageView加入到ViewGroup  
            vg.addView(ivPointArray[i]);  
        }  



    }  

    /** 
     * 加载图片ViewPager 
     */  
    private void initViewPager() {  
        vp = (ViewPager) findViewById(R.id.guide_vp);  
        //实例化图片资源  
        imageIdArray = new int[]{R.mipmap.guide1,R.mipmap.guide2,R.mipmap.guide3};  
        viewList = new ArrayList<>();  
        //获取一个Layout参数，设置为全屏  
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(  
                LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.MATCH_PARENT);  

        //循环创建View并加入到集合中  
        int len = imageIdArray.length;  
        for (int i = 0;i<len;i++){  
            //new ImageView并设置全屏和图片资源  
            ImageView imageView = new ImageView(this);  
            imageView.setLayoutParams(params);  
            imageView.setBackgroundResource(imageIdArray[i]);  

            //将ImageView加入到集合中  
            viewList.add(imageView);  
        }  

        //View集合初始化好后，设置Adapter  
        vp.setAdapter(new GuidePageAdapter(viewList));  
        //设置滑动监听  
        vp.setOnPageChangeListener(this);  
    }  


    @Override  
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {  

    }  

    /** 
     * 滑动后的监听 
     * @param position 
     */  
    @Override  
    public void onPageSelected(int position) {  
        //循环设置当前页的标记图  
        int length = imageIdArray.length;  
        for (int i = 0;i<length;i++){  
            ivPointArray[position].setBackgroundResource(R.mipmap.full_holo);  
            if (position != i){  
                ivPointArray[i].setBackgroundResource(R.mipmap.empty_holo);  
            }  
        }  

        //判断是否是最后一页，若是则显示按钮  
        if (position == imageIdArray.length - 1){  
            ib_start.setVisibility(View.VISIBLE);  
        }else {  
            ib_start.setVisibility(View.GONE);  
        }  
    }  


    @Override  
    public void onPageScrollStateChanged(int state) {  

    }  
}  

总的来说实现流程比较简单。

1）先加载ViewPager，新建ImageView并添加到View集合中，然后设置Adapter并显示。

2）然后加载LinearLayout，放置原点图片，同样新建ImageView设置背景后放在圆点图集合中。

3）最后设置ViewPager的滑动监听事件，在滑动完成的监听OnPageSelected方法中，设置对应的圆点为选中，如果是最后一页，则显示按钮。