ViewPager（实现引导页功能）

• 首先在引导界面的布局文件定义一个ViewPager：

• 再定义几个ImageView来显示不同的图片：
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:id="@+id/ll"
  android:layout_alignParentBottom="true"
  android:orientation="horizontal"
  android:gravity="center_horizontal">

• 设置ViewPager的Adapter，继承自PagerAdapter：

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

• 最后在onCreate方法中设置Adapter：

    adapter=new MyAdapter(views,this);
    vp= (ViewPager) findViewById(R.id.vp);
    vp.setAdapter(adapter);
  

• 在每个图片下面添加导航点，这就需要调用ViewPager的setOnPageChangeListener(this)方法了。并覆盖onPageSelected(int position)。

    @Override
    public void onPageSelected(int position) {
        for (int i = 0; i < ids.length; i++) {
        //被选中的页面的导航点颜色要更深一些
            if (position == i) {
                dots[i].setImageResource(R.drawable.login_point_selected);
            } else {
                dots[i].setImageResource(R.drawable.login_point);
            }
        }
    }
  

• 第一次启动应用是启动欢迎界面，在启动引导界面，最后启动主界面，第二次后就不启动引导界面了，通过Handler来发送消息。

    public static final int time=2000;
    public static final int GOHMOE =1000;
    public static final int GOGUILD =1001;
  
    private boolean isFistIn=false;
  
    private Handler mHandler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case GOHMOE:
                    goHome();
                    break;
                case GOGUILD:
                    goGuild();
                    break;
            }
        }
    };
    
    private void goHome(){
    Intent intent=new Intent(WelcomAty.this,MainActivity.class);
    startActivity(intent);
    finish();
    }private void goGuild(){
    Intent intent=new Intent(WelcomAty.this,Guild.class);
    startActivity(intent);
    finish();
    }
  
    private void init(){
    SharedPreferences preferences= getSharedPreferences("jike",MODE_PRIVATE);
    isFistIn=preferences.getBoolean("isFistIn",true);
    if (!isFistIn){
        mHandler.sendEmptyMessageDelayed(GOHMOE,time);
    }else {
  
    mHandler.sendEmptyMessageDelayed(GOGUILD,time);
        SharedPreferences.Editor editor=preferences.edit();
        editor.putBoolean("isFistIn",false);
        editor.commit();
        }
    }