Android引导界面的实现分析

一、实现过程

1.设计引导界面整体布局，修改自动生成的 activity_guide.xml 文件，在布局文件里首先加 入 ViewPager 这个组件，然后加入加入四个 ImageView 组件，主要代码如下： 

<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=".GuideActivity" >    <android.support.v4.view.ViewPager        android:id="@+id/vpGuide"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true" >    </android.support.v4.view.ViewPager>    <!-- 底部的四个圆点 -->    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_centerHorizontal="true"        android:layout_marginBottom="40dp" >        <ImageView            android:id="@+id/guide_dot1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:background="@drawable/bg_point_selected" />        <ImageView            android:id="@+id/guide_dot2"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginLeft="10dp"            android:background="@drawable/bg_point" />        <ImageView            android:id="@+id/guide_dot3"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginLeft="10dp"            android:background="@drawable/bg_point" />        <ImageView            android:id="@+id/guide_dot4"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginLeft="10dp"            android:background="@drawable/bg_point" />    </LinearLayout></RelativeLayout>

其中 bg_point_selected.xml 文件如下：

<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"    android:shape="oval" >    <solid android:color="#427AB7" />    <size        android:height="8dp"        android:width="8dp" /></shape>

bg_point.xml 文件如下： 

<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"    android:shape="oval" >    <!-- 未被选中 -->    <solid android:color="@android:color/black" />    <size        android:height="8dp"        android:width="8dp" /></shape>

2.定义好要切换的布局文件 view1_of_pager.xml 文件、view2_of_pager.xml 文件、 view3_of_pager.xml 文件、view4_of_pager.xml 文件 view1_of_pager.xml 文件、view2_of_pager.xml 文件、view3_of_pager.xml 文件布局类似，只有背景图片不同。

<?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/guide_1"    android:orientation="vertical" ></LinearLayout>

view4_of_pager.xml 文件代码如下： 

<?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/guide_1"    android:orientation="vertical" >    <TextView        android:id="@+id/tvGo"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_alignParentRight="true"        android:layout_marginBottom="16dp"        android:layout_marginRight="19dp"        android:background="@drawable/start_select"        android:gravity="center"        android:text="Go"        android:textColor="#ffffff"        android:textSize="30sp" /></RelativeLayout>

其中 start_select.xml 文件如下： 

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

start_before.xml 文件如下： 

<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"    android:shape="oval" >    <solid android:color="#2362A7" />    <size        android:height="80dp"        android:width="80dp" /></shape>

3.编写 GuideAdapter 类，继承 PageAdapter 

public class GuideAdapter extends PagerAdapter { private List<View> views; public GuideAdapter(List<View> views) { this.views = views; } @Overridepublic int getCount() { return views.size(); } @Override public boolean isViewFromObject(View view, Object object) { return view == object; } @Override public Object instantiateItem(ViewGroup container, int position) { container.addView(views.get(position)); return views.get(position); } @Override public void destroyItem(ViewGroup container, int position, Object object) {  View view = views.get(position); container.removeView(view); }} 

4.修改 GuideActivity 类，代码如下：

public class GuideActivity extends Activity { private List<View> guideViews;   private ViewPager vpGuide;    private int[] guide_dots = {R.id.guide_dot1,R.id.guide_dot2,R.id.guide_dot3,R.id.guide_dot4};// 4 个导航点    private ImageView[] dots;     private TextView tvGo;  @Override  protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);  setContentView(R.layout.activity_guide);   initGuideViews();  tvGo=(TextView) findViewById(R.id.tvGo); initDots();  setListeners();}  }private void initDots() { dots=new ImageView[4]; for(int i=0;i<dots.length;i++){ dots[i]=(ImageView) findViewById(guide_dots[i]); } }  private void setListeners() { vpGuide.setOnPageChangeListener(new OnPageChangeListener() {     @Overridepublic void onPageSelected(int position) { for (int i = 0; i < guide_dots.length; i++) { if (position == i) {    dots[i].setImageResource(R.drawable.bg_point_selected);     } else {    dots[i].setImageResource(R.drawable.bg_point); }   }  }       @Override   public void onPageScrolled(int arg0, float arg1, int arg2) {  }       @Overridepublic void onPageScrollStateChanged(int arg0) { }  });   tvGo.setOnClickListener(new OnClickListener() { @Override   public void onClick(View view) {  Intent intent=new Intent(GuideActivity.this,LoginActivity.class);startActivity(intent); }  }); } private void initGuideViews() { vpGuide=(ViewPager) findViewById(R.id.vpGuide);   //准备好切换的 viewguideViews=new ArrayList<View>(); LayoutInflater layoutInflater=LayoutInflater.from(this);guideViews.add(layoutInflater.inflate(R.layout.view1ofpager, null));guideViews.add(layoutInflater.inflate(R.layout.view2ofpager, null)); guideViews.add(layoutInflater.inflate(R.layout.view3ofpager, null)); guideViews.add(layoutInflater.inflate(R.layout.view4ofpager, null)); GuideAdapter guideAdapter=new GuideAdapter(guideViews); vpGuide.setAdapter(guideAdapter);}} 

二、运行界面效果图

 通过引导界面，用户能够快速了解应用的主要功能。当滑动到最后一个界面时，点击 Go 进入到主界面。