android 开发笔记 图片轮播

package com.guanyueyun.mylook.view;import android.content.Context;import android.os.Handler;import android.os.Message;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.RelativeLayout;import com.guanyueyun.mylook.R;import com.guanyueyun.mylook.bean.AdvertInfo;import com.squareup.picasso.Picasso;import java.util.ArrayList;import java.util.List;/** * 图片轮播的组合控件 * * 从网络中获取了数据并且进行解析之后拿到轮播的数据源 * 伪无限轮播：给定Viewapager的页卡初始化为很大的值，然后每次从中间的某一个位置开始。这样左右在用户滑动的时候都相当于滑不到底部 * 自动轮播:添加线程用于三秒发送信息给主线程更新UI。 * * 添加dot点的内容显示 * * * 凡是进行new出来的控件在进行添加的时候都需要指定宽和高。 * 换句话来说就是指定LayoutParams。 * * 手动切换ViewPager会触发Viewager的滑动监听的方法----onPageScrollStateChanged，该方法中有三种状态可以进行操作。 * * */public class AdvertView {    private RelativeLayout mRelative;//返回的显示视图    private  List<AdvertInfo> list;    private  Context context;    private ViewPager viewPager;//图片轮播对象    private List<View> pagerList;    private LinearLayout dotLinear;//dot点的布局    private boolean isAlive = true;//控制线程是否存在    private boolean isRunning = true;//控制是否发送UI来更新操作    private DotThread thread;//线程对象    //控制接收子线程发送的消息，是否更新下一页的操作    private Handler handler = new Handler(new Handler.Callback() {        @Override        public boolean handleMessage(Message msg) {            int currentItem = viewPager.getCurrentItem();            //切换到下一个页卡进行显示            viewPager.setCurrentItem(++currentItem);            return true;        }    });    //停止更新    public AdvertView(List<AdvertInfo> list, Context context) {        this.list = list;        this.context = context;    }    //提供视图的方法给外界进行调用    public View getView(){        if (mRelative==null){            initViews();        }        return mRelative;    }    //内部控件的初始化    private void initViews() {        //最外层的relativeLayout的初始化        mRelative = new RelativeLayout(context);        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.MATCH_PARENT);        mRelative.setLayoutParams(lp);        //viewpager        initViewPager();        //圆点呈现的线性布局        initDotLinear();        //给Viewpager添加页卡切换的监听        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {            @Override            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {            }            //页卡选中的方法            @Override            public void onPageSelected(int position) {                checkPoint(position%list.size());            }            @Override            public void onPageScrollStateChanged(int state) {                switch (state){                    case ViewPager.SCROLL_STATE_DRAGGING://拖拽                        //关闭切换                        isRunning  = false;                        break;                    case ViewPager.SCROLL_STATE_IDLE://空闲                        isRunning = true;                        break;                    case ViewPager.SCROLL_STATE_SETTLING://滑翔                        break;                }            }        });    }    //初始化dot布局    private void initDotLinear() {        dotLinear = new LinearLayout(context);        RelativeLayout.LayoutParams dotLp = new RelativeLayout.LayoutParams(-2,-2);        dotLp.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM,RelativeLayout.TRUE);//添加规则底部对齐   属性名称 verb  属性填充的值anchor        dotLp.addRule(RelativeLayout.CENTER_HORIZONTAL, RelativeLayout.TRUE);//水平居中        dotLinear.setOrientation(LinearLayout.HORIZONTAL);//设置水平呈现        dotLinear.setLayoutParams(dotLp);//设置显示的layoutparams        mRelative.addView(dotLinear);        //呈现圆点        createDots();    }    //初始化显示的点    private void createDots() {        for (int i = 0; i < list.size(); i++) {            ImageView iv = new ImageView(context);            LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(-2,-2);            lp.leftMargin = 10;            lp.rightMargin = 10;            lp.bottomMargin = 10;            lp.height = 10;            lp.weight = 10;            iv.setLayoutParams(lp);//设置呈现的layoutparams            dotLinear.addView(iv);        }        //设置选中的点        checkPoint(0);    }    //设置选中的位置呈现的点    private void checkPoint(int index) {        for (int i = 0; i < list.size(); i++) {            //取出在dotLinerar中每一个Imageview            ImageView iv  = (ImageView) dotLinear.getChildAt(i);            if (index==i){                //设置颜色白色                iv.setBackgroundResource(R.mipmap.tabmain_dot_icon_unselect);            }else{                //设置灰色背景                iv.setBackgroundResource(R.mipmap.tabmain_dot_icon);            }        }    }    private void initViewPager() {        viewPager = new ViewPager(context);        RelativeLayout.LayoutParams pagerLp = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);        viewPager.setLayoutParams(pagerLp);        mRelative.addView(viewPager);        //初始化适配器的数据源        initViewPagerList();        //适配器        AdvertAdapter adapter =new AdvertAdapter();        viewPager.setAdapter(adapter);        viewPager.setCurrentItem(list.size()*500);//设置中间的显示位置    }    //初始化适配显示的数据源view    private void initViewPagerList() {        pagerList = new ArrayList<>();        for (int i = 0; i < list.size(); i++) {            ImageView iv = new ImageView(context);            iv.setScaleType(ImageView.ScaleType.FIT_XY);            //picasso赋值            Picasso.with(context).load(list.get(i).getImage().getUrl()).into(iv);            pagerList.add(iv);        }    }    //自送开始更新轮播    public void startUpdate(){        if (thread==null) {            thread = new DotThread();            thread.start();        }    }    //停止更新    public void stopUpdate() {        isRunning = false;        isAlive = false;        if (thread!=null){            thread=null;        }    }    public class DotThread extends Thread{        @Override        public void run() {            super.run();            //如果线程还在            while(isAlive){                //是否需要发送                if (isRunning){                    //切换页卡--发送空消息                    handler.sendEmptyMessage(0);                    try {                        Thread.sleep(3000);                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                }            }        }    }    //viewpager的适配器显示    class AdvertAdapter extends PagerAdapter{        @Override        public int getCount() {            return Integer.MAX_VALUE;//大值        }        @Override        public boolean isViewFromObject(View view, Object object) {            return view==object;        }        @Override        public Object instantiateItem(ViewGroup container, int position) {            container.addView(pagerList.get(position%list.size()));            return pagerList.get(position%list.size());        }        @Override        public void destroyItem(ViewGroup container, int position, Object object) {//            super.destroyItem(container, position, object);            container.removeView(pagerList.get(position%list.size()));        }    }}