ViewPager封装工具类： 轻松实现APP导航或APP中的广告栏

  相信做app应用开发的，绝对都接触过ViewPager，毕竟ViewPager的应用可以说无处不在；APP第一次启动时的新手导航页，APP中结合Fragment实现页面滑动，APP中常见的广告栏的自动滑动（也可手动滑动）。 ViewPager有这么多好处，在APP中到处都可能会用到，那大家岂不是要写好多重复的代码呢？ 作为有思想的开发者，我们应当想到，把ViewPager封装起来，做成一个更好使用，更加强大的工具！

  不多说，直接贴代码：

package com.lnyp.viewpagerhelper;import android.os.Handler;import android.os.Message;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.LinearLayout;import java.util.List;import java.util.concurrent.atomic.AtomicInteger;/** * ViewPager帮助类，可用于app的引导页，app的广告栏 **/public class ViewPagerHelper {    // 判断是否自动滑动    private boolean mIsAuto;    private ViewPager mViewPager;    private List<View> mViews;    private LinearLayout mIndicatorParents; // 指示器容器    private PagerAdapter mPagerAdapter;    private int mSelect;    private int mUnSelect;    private OnViewInstantiateListener mOnViewInstantiateListener;    // 一个提供原子操作的Integer的类    private AtomicInteger atomicInteger = new AtomicInteger(0);    // 广告不停的循环播放    private boolean isContinue = true;    /*     * 每隔固定时间切换广告栏图片     */    private final Handler viewHandler = new Handler() {        @Override        public void handleMessage(Message msg) {            if (msg.what == mViews.size()) {                mViewPager.setCurrentItem(1);            } else {                mViewPager.setCurrentItem(msg.what);            }            super.handleMessage(msg);        }    };    /**     * View 被附加到viewpager的时候调用     */    public interface OnViewInstantiateListener {        public void onInstantiate(int position, View view);    }    /**     * @param isAuto              指定该ViewPager中的内容是否自动滑动，true为自动滑动，false为手动滑动     * @param viewPager     * @param views               加载到ViewPager中的View的集合     * @param indicatorParents    导航页下面小圆点的父容器     * @param selectDrawableRes   选中页显示的导航点的图片     * @param unselectDrawableRes 未选中页的导航点的图片     */    public ViewPagerHelper(boolean isAuto, ViewPager viewPager, List<View> views, LinearLayout indicatorParents,                           int selectDrawableRes, int unselectDrawableRes) {        mIsAuto = isAuto;        mViewPager = viewPager;        mViews = views;        mIndicatorParents = indicatorParents;        mSelect = selectDrawableRes;        mUnSelect = unselectDrawableRes;        init();    }    /**     * 设置atomicInteger     */    private void atomicOption() {        atomicInteger.incrementAndGet();        if (atomicInteger.get() > mViews.size() - 1) {            atomicInteger.getAndAdd(-mViews.size());        }        try {            Thread.sleep(5000);        } catch (InterruptedException e) {        }    }    public ViewPager getViewPager() {        return mViewPager;    }    public List<View> getViews() {        return mViews;    }    public void setOnViewInstantiateListener(OnViewInstantiateListener listener) {        mOnViewInstantiateListener = listener;    }    /**     *     */    private void init() {        mPagerAdapter = new PagerAdapter() {            @Override            public int getCount() {                return mViews.size();            }            @Override            public boolean isViewFromObject(View arg0, Object arg1) {                return arg0 == (arg1);            }            @Override            public int getItemPosition(Object object) {                View view = (View) object;                if (mViews.contains(view)) {                    return mViews.indexOf(view);                }                return POSITION_NONE;            }            @Override            public void destroyItem(ViewGroup container, int position, Object object) {                container.removeView(mViews.get(position));// 删除页卡            }            @Override            public Object instantiateItem(ViewGroup container, int position) {                View view = mViews.get(position);                container.addView(view, 0);                if (mOnViewInstantiateListener != null) {                    mOnViewInstantiateListener.onInstantiate(position, view);                }                return mViews.get(position);            }        };        mViewPager.setAdapter(mPagerAdapter);        mViewPager.addOnPageChangeListener(new OnPageChangeListener() {            @Override            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {                // 从1到2滑动，在1滑动前调用            }            @Override            public void onPageSelected(int position) {                // activity从1到2滑动，2被加载后掉用此方法                switchBannerIndicator(position);            }            @Override            public void onPageScrollStateChanged(int state) {                // 状态有三个0空闲，1是正在滑行中，2目标加载完毕            }        });        if (mIndicatorParents != null) {            for (int i = 0; i < mViews.size(); i++) {                // 导航点直接的间距                int margin = 20;                // 设置未选中的也没的导航点的图片                ImageView view = new ImageView(mViewPager.getContext());                view.setBackgroundResource(mUnSelect);                // 设置图片的属性                LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);                if (i < mViews.size() - 1) {                    params.rightMargin = margin;                }                // 将导航点加入到容器中                mIndicatorParents.addView(view, params);            }            // 单独设置选中的导航点的图片            mIndicatorParents.getChildAt(0).setBackgroundResource(mSelect);        }        /**         * 判断是否自动更新View         */        if (mIsAuto) {            // 启动线程，定时更改View            new Thread(new Runnable() {                @Override                public void run() {                    while (true) {                        if (isContinue) {                            viewHandler.sendEmptyMessage(atomicInteger.get());                            atomicOption();                        }                    }                }            }).start();        }    }    /**     * 设置指示器当前页码     */    private void switchBannerIndicator(int index) {        if (mIndicatorParents != null) {            for (int i = 0; i < mIndicatorParents.getChildCount(); i++) {                View view = mIndicatorParents.getChildAt(i);                if (i == index) {                    view.setBackgroundResource(mSelect);                } else {                    view.setBackgroundResource(mUnSelect);                }            }        }    }}

  代码中注释已经很详细了，不多解释，下面来看看如何使用该ViewPagerHelper，我们用它来试下你APP的新手导航页：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical">    <android.support.v4.view.ViewPager        android:id="@+id/viewpager"        android:layout_width="fill_parent"        android:layout_height="fill_parent" />    <LinearLayout        android:id="@+id/dots_parent"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_centerHorizontal="true"        android:gravity="center"        android:layout_marginBottom="20dp"        android:orientation="horizontal" /></RelativeLayout>

import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.support.v4.view.ViewPager;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.view.Window;import android.view.WindowManager;import android.widget.LinearLayout;import java.util.ArrayList;import java.util.List;import butterknife.Bind;import butterknife.ButterKnife;/** * 新手导航页 * * @author lining */public class GudieActivity extends Activity {    private List<View> views = null;    @Bind(R.id.viewpager)    public ViewPager mViewPager;    @Bind(R.id.dots_parent)    public LinearLayout viewPoints;    @Override    protected void onCreate(Bundle savedInstanceState) {        this.requestWindowFeature(Window.FEATURE_NO_TITLE);        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,                WindowManager.LayoutParams.FLAG_FULLSCREEN);        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_guide);        ButterKnife.bind(this);        this.initDatas();    }    /**     * 初始化数据     */    private void initDatas() {        views = new ArrayList<View>();        View view1 = LayoutInflater.from(this).inflate(R.layout.page_guide_first, null);        View view2 = LayoutInflater.from(this).inflate(R.layout.page_guide_second, null);        View view3 = LayoutInflater.from(this).inflate(R.layout.page_guide_third, null);        views.add(view1);        views.add(view2);        views.add(view3);        view3.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                Intent intent = new Intent(GudieActivity.this, MainActivity.class);                GudieActivity.this.startActivity(intent);                GudieActivity.this.finish();            }        });        new ViewPagerHelper(true, mViewPager, views, viewPoints, R.mipmap.page_indicator_focused,                R.mipmap.page_indicator_unfocused);    }}

 注： 请着重看下这行代码：

new ViewPagerHelper(false, mViewPager, views, viewPoints, R.mipmap.page_indicator_focused, R.mipmap.page_indicator_unfocused);

  没错，使用ViewPagerHelper就这么简单的一句！！！ 只要把需要的参数传递过去即可啦，看下效果：

  有没有被惊艳到？

  好吧，确实没啥惊艳的，哈哈，不过我想，该工具类确实能很好的帮助大家精简以后的开发工作！

实例源码下载地址（免费）：http://download.csdn.net/detail/zuiwuyuan/9212197