常常会有一些APP开发需要用到启动画面或者引导页面，启动页面正常都是一些简单的Logo或者图片之类，主要是能实现一些后台数据的加载。而引导页面可以通过左右滑动方式传达信息（APP介绍，新功能，插入广告等）给用户。

简单实现启动画面

两种方法的实现：

一 建立一个activity，展示启动画面，然后再跳转到主Activity。

public class WelcomeActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //设置无标题
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        //设置全屏
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_welcome);
        new Handler().postDelayed(new Runnable() {//一秒后跳转到主页面
            public void run() {
                // 跳转至 MainActivity
                Intent intent = new Intent(WelcomeActivity.this, MainActivity.class);
                startActivity(intent);
                WelcomeActivity.this.finish();//如果没有finish掉，按回退键就会回到欢迎界面不合理。
            }
        }, 1000);
    }
}

布局layout.activity_welcome.xml：只添加一张背景图片

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@mipmap/timg">
</LinearLayout>

二 在同一个activity展示启动画面，后进行隐藏。

public class Welcome2Activity extends Activity implements Animation.AnimationListener {
    LinearLayout welcomelinearLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_welcome2);
        AlphaAnimation animation = new AlphaAnimation(0.0f, 1.0f);//2秒渐变
        animation.setDuration(2000);
        welcomelinearLayout = (LinearLayout) findViewById(R.id.welcome);
        welcomelinearLayout.setAnimation(animation);
        animation.setAnimationListener(this);

    }

    @Override
    public void onAnimationStart(Animation animation) {
        welcomelinearLayout.setVisibility(View.VISIBLE);//开始时进行显示
    }

    @Override
    public void onAnimationEnd(Animation animation) {
        welcomelinearLayout.setVisibility(View.GONE);  //结束时进行隐藏起来
    }

    @Override
    public void onAnimationRepeat(Animation animation) {

    }
}

布局layout.activity_welcome2.xml

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

    <LinearLayout
        android:id="@+id/welcome"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@mipmap/timg"
        android:orientation="vertical"></LinearLayout>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:text="Welcome To MainActivity!"
        android:textSize="24sp" />
</LinearLayout>

简单实现引导页

这里是用ViewPager实现引导页。

介绍：引导页有四个可以左右滑动的页面，最后一个页面有一个按钮点击可进入主页面。

分别创建4个子布局welcome_item1.xml，welcome_item2.xml，welcome_item3.xml都是一样布局background设置不一样图片而已

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/timg"
    android:orientation="vertical">

</LinearLayout>

welcome_item4.xml也就多一个按钮

<?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:background="@drawable/timg4"
    android:orientation="vertical">

    <Button
        android:id="@+id/Bt_start"
        android:layout_width="200dp"
        android:layout_height="80dp"
        android:layout_centerInParent="true"
        android:layout_margin="10dp"
        android:text="进入主页面"
        android:textSize="20sp" />
</RelativeLayout>

接下来我们来看看主布局activity_welcome4.xml，主页面分两个模块一个是ViewPager还一个是要实现底部的小圆点功能：

<?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:orientation="vertical">

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

    <LinearLayout
        android:id="@+id/spot_linearLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="24dp"
        android:orientation="horizontal"></LinearLayout>
</RelativeLayout>

接下来编写小圆点的selector，分为选中和没选中两种状态。

<?xml version="1.0" encoding="UTF-8"?>
<selector
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_enabled="true" android:drawable="@drawable/dark_dot" />
    <item android:state_enabled="false" android:drawable="@drawable/white_dot" />
</selector>

dark_dot.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval" >
    <solid android:color="#33ccff"/>
    <size android:width="20dp"
    android:height="20dp"/>
</shape>

white_dot

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval" >
    <solid android:color="#ccffbb"/>
    <size android:width="20dp"
    android:height="20dp"/>
</shape>

接下来就是activity部分，先上全码

public class Welcome4Activity extends Activity implements ViewPager.OnPageChangeListener {
    private ViewPager welcome_vp;
    private ArrayList<View> ViewList;
    private Button Bt_start;
    private View view1, view2, view3, view4;
    //底部小点图片
    private ImageView[] dots;
    //引导页个数
    private int Number=4;
    //记录当前选中位置
    private int currentIndex;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //设置无标题
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        //设置全屏
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_welcome4);
        initData();
        //初始化底部小点
        initDots();
        welcome_vp = (ViewPager) findViewById(R.id.welcome_vp);
        WelcomeVPAdapter adapter = new WelcomeVPAdapter();
        welcome_vp.setAdapter(adapter);
        welcome_vp.addOnPageChangeListener(this);
        Bt_start = (Button) view4.findViewById(R.id.Bt_start);
        Bt_start.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                goToActivity(MainActivity.class.getName());
                finish();
            }
        });

    }

    //初始化底部小点
    private void initDots() {
        LinearLayout spot_linearLayout = (LinearLayout) findViewById(R.id.spot_linearLayout);
        //根据个数添加对应小点的ImageView
        for (int i = 0; i < Number; i++) {
            ImageView iv = new ImageView(this);
            iv.setImageResource(R.drawable.dot);
            iv.setPadding(30, 30, 30, 30);
            spot_linearLayout.addView(iv);
        }
        dots = new ImageView[Number];
        //循环取得小点图片
        for (int i = 0; i < Number; i++) {
            dots[i] = (ImageView) spot_linearLayout.getChildAt(i);
            dots[i].setEnabled(true);//全部设置颜色为不选中状态
        }
        currentIndex = 0;
        dots[currentIndex].setEnabled(false);//默认第一个选中状态
    }

    private void setCurDot(int positon) {
        if (positon < 0 || positon > Number - 1 || currentIndex == positon) {
            return;
        }
        dots[positon].setEnabled(false);
        dots[currentIndex].setEnabled(true);
        currentIndex = positon;
    }

    //初始化数据
    private void initData() {
        ViewList = new ArrayList<View>();
        view1 = LayoutInflater.from(this).inflate(R.layout.welcome_item1, null);
        view2 = LayoutInflater.from(this).inflate(R.layout.welcome_item2, null);
        view3 = LayoutInflater.from(this).inflate(R.layout.welcome_item3, null);
        view4 = LayoutInflater.from(this).inflate(R.layout.welcome_item4, null);
        ViewList.add(view1);
        ViewList.add(view2);
        ViewList.add(view3);
        ViewList.add(view4);
    }

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

    }

    @Override
    public void onPageSelected(int position) {
        setCurDot(position);
    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }


    class WelcomeVPAdapter extends PagerAdapter {

        //返回可以滑动的VIew的个数
        @Override
        public int getCount() {
            return ViewList.size();
        }

        //滑动切换的时候销毁当前的组件
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView(ViewList.get(position));
        }

        //将当前视图添加到container中并返回当前View视图
        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            container.addView(ViewList.get(position));
            return ViewList.get(position);
        }

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

    protected void goToActivity(String className) {
        Intent intent = new Intent();
        intent.setClassName(getBaseContext(), className);
        startActivity(intent);
    }

}

首先肯定是初始化数据咯
这里有三个个模块的初始化（点击按钮的就不说了）

• view的初始化

 //初始化数据
    private void initData() {
        ViewList = new ArrayList<View>();
        view1 = LayoutInflater.from(this).inflate(R.layout.welcome_item1, null);
        view2 = LayoutInflater.from(this).inflate(R.layout.welcome_item2, null);
        view3 = LayoutInflater.from(this).inflate(R.layout.welcome_item3, null);
        view4 = LayoutInflater.from(this).inflate(R.layout.welcome_item4, null);
        ViewList.add(view1);
        ViewList.add(view2);
        ViewList.add(view3);
        ViewList.add(view4);
    }

• 小圆点的初始化

  //初始化底部小点
    private void initDots() {
        LinearLayout spot_linearLayout = (LinearLayout) findViewById(R.id.spot_linearLayout);
        //动态添加小圆点的ImageView
        for (int i = 0; i < Number; i++) {
            ImageView iv = new ImageView(this);
            iv.setImageResource(R.drawable.dot);
            iv.setPadding(30, 30, 30, 30);
            spot_linearLayout.addView(iv);
        }
        dots = new ImageView[Number];
        //循环取得小点图片
        for (int i = 0; i < Number; i++) {
            dots[i] = (ImageView) spot_linearLayout.getChildAt(i);
            dots[i].setEnabled(true);//全部设置颜色为不选中状态
        }
        currentIndex = 0;
        dots[currentIndex].setEnabled(false);//默认第一个选中状态
    }

我们知道ViewPager类需要一个PagerAdapter适配器类给它提供数据
所以

    class WelcomeVPAdapter extends PagerAdapter {

        //返回可以滑动的VIew的个数
        @Override
        public int getCount() {
            return ViewList.size();
        }

        //滑动切换的时候销毁当前的组件
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView(ViewList.get(position));
        }

        //将当前视图添加到container中并返回当前View视图
        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            container.addView(ViewList.get(position));
            return ViewList.get(position);
        }

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

然后我们还需要实现了OnPageChangeListener接口，对ViewPager滑动事件作出相应的反应。

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

    }

    @Override
    public void onPageSelected(int position) {
        setCurDot(position);//在这里我们进行小点状态的修改
    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }

ok一个简单的引导页实现了！

1.png