android-ViewPager实现图片自动切换

本文实现的是像viewpager图片轮播的功能、左右滑动的时候能够流畅的切换图片、并且没有边界限制

 1、activity_main.xml布局

<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"    >    <RelativeLayout        android:id="@+id/my_viewpager"        android:layout_width="match_parent"        android:layout_height="match_parent"/></RelativeLayout>

因为我的ViewPager是继承RelativeLayout

2、layout_recommend_item.xml中的布局

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent">    <ImageView        android:id="@+id/iv_pic"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:src="@mipmap/ic_launcher"        android:layout_weight="1"/>    <TextView        android:id="@+id/tv_desc"        android:text="123"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>
ImageView是显示图片 TextView用来显示每一个pager的标题

2、MyViewPager类，因为图个方便，把能够实现这个功能否合成一个类、这样用起来比较方便

import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Handler;import android.os.Message;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.util.DisplayMetrics;import android.util.Log;import android.util.TypedValue;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.RelativeLayout;import android.widget.TextView;import java.util.ArrayList;import java.util.List;public class MyViewPager extends RelativeLayout {    private static final int START_SCROLL = 1;    private static final int SCROLL_NEXT = 2;    private static final int SHOW_TIME = 5000;//显示时间    private List<String> mDatas = new ArrayList<>();//viewpager每一页对应的标题    private ViewPager mPager;    private Context mContext;    private int mWidth, mHeight;   //viewpager的宽高    private int mTitleHeight;      //标题高度    private TipView mTipView;       //标题对应的view    //在主ui中更新viewpager，也就是切换图片    private static Handler sHandler = new Handler() {        @Override        public void handleMessage(Message msg) {            int w = msg.what;            ViewPager pager = (ViewPager) msg.obj;            switch (w) {                case START_SCROLL:                    pager.setCurrentItem(msg.arg1, true);                    break;                case SCROLL_NEXT:                    pager.setCurrentItem(msg.arg1, true);                    break;            }        }    };    /**     * 构造函数     * @param context content     * @param w 要显示的viewpager的宽     * @param h 要显示的viewpager的高     */    public MyViewPager(Context context, int w, int h) {        super(context);        mContext = context;        mWidth = w;        mHeight = h;        initView(); //取得数据 左边随便取的 只是为了看起来有效果//        对viewpager滑动进行监听        mPager.setOnPageChangeListener(new MOnPagerChangeListener());        init();        DisplayMetrics dm = mContext.getResources().getDisplayMetrics();        mTitleHeight = cm_DptoPx(48, dm);    }    /**     * 对viewpager控件进行绘制宽高     */    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        ViewGroup.LayoutParams vp = getLayoutParams();        if (vp != null) {            vp.width = mWidth;            vp.height = mHeight;        }        super.onMeasure(widthMeasureSpec, heightMeasureSpec);    }    /**     * 把dp转化成px     */    public static int  cm_DptoPx(int dp,DisplayMetrics dis){        return  (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, dis);    }    private void init() {        getData();    }    private void initView() {        mPager = new ViewPager(mContext);        RelativeLayout.LayoutParams rp = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);        addView(mPager, rp);    }    public void getData() {        for (int i = 0; i < 4 ; i++){            mDatas.add(i,"viewpager"+i);        }        sHandler.postDelayed(new Runnable() {            @Override            public void run() {                stopAnimation();                initTipView();                mPager.setAdapter(new RecommendAdapter());                mPager.setCurrentItem(10000 * mDatas.size());            }        }, 2000);    }    /**     * 删除队列中的消息     */    public void stopAnimation() {        sHandler.removeMessages(START_SCROLL);        sHandler.removeMessages(SCROLL_NEXT);    }    public void startAnimation() {        if (mDatas.size() == 0) {            return;        }        Message msg = sHandler.obtainMessage(START_SCROLL);        msg.obj = mPager;        msg.arg1 = (mPager.getCurrentItem() + 1);//取得后一张图片        sHandler.sendMessageDelayed(msg, SHOW_TIME);//5秒后发送给ui线程    }    /**     * 对标题view移动的光标初始化     */    private void initTipView() {        if (mTipView == null) {            RelativeLayout.LayoutParams rp = new RelativeLayout.LayoutParams(10, 10);            rp.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);            rp.bottomMargin = mTitleHeight;            mTipView = new TipView(mContext, mDatas.size());            addView(mTipView, rp);        } else {            mTipView.setCount(mDatas.size());        }    }    private class MOnPagerChangeListener implements ViewPager.OnPageChangeListener {        private int curState;        @Override        public void onPageScrolled(int i, float v, int i1) {        }        @Override        public void onPageSelected(int i) {  //滑动结束            sHandler.removeMessages(SCROLL_NEXT);            sHandler.removeMessages(START_SCROLL);            if(curState == ViewPager.SCROLL_STATE_DRAGGING){                return;            }            Message msg = sHandler.obtainMessage(SCROLL_NEXT);            msg.arg1 = i + 1;            msg.obj = mPager;            sHandler.sendMessageDelayed(msg, SHOW_TIME);            mTipView.setCurPostion(i % mDatas.size());        }        @Override        public void onPageScrollStateChanged(int i) { //正在滑动时            curState = i;            if(i == ViewPager.SCROLL_STATE_DRAGGING){ //SCROLL_STATE_DRAGGING正在滑动 SCROLL_STATE_IDLE什么都没有做                //SCROLL_STATE_SETTLING 滑动完毕                stopAnimation();            }else {                if(!(sHandler.hasMessages(START_SCROLL)&&sHandler.hasMessages(SCROLL_NEXT))){                    startAnimation();                }            }        }    }    private class RecommendAdapter extends PagerAdapter {        @Override        public Object instantiateItem(ViewGroup container, int position) {            Log.i("MyViewPager","instantiateItem ");            int curPos = position % mDatas.size();            View view = View.inflate(mContext, R.layout.layout_recommend_item, null);            ViewGroup.LayoutParams vp = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);            ImageView iv = (ImageView) view.findViewById(R.id.iv_pic);            TextView tv = (TextView) view.findViewById(R.id.tv_desc);            tv.setText(mDatas.get(curPos));            container.addView(view, vp);            view.setTag(curPos);            view.setOnClickListener(new OnClickListener() {                @Override                public void onClick(View v) {                }            });            return view;        }        @Override        public int getCount() {            return Integer.MAX_VALUE;        }        @Override        public boolean isViewFromObject(View view, Object o) {            return view == o;        }        @Override        public void destroyItem(ViewGroup container, int position, Object object) {            container.removeView((View) object);        }    }    private class TipView extends View {        private int mPadding;        private int mCount;        private int mCurPos;        private Paint mNorPaint;        private Paint mSelPaint;        private int mHeight;        public TipView(Context context, int count) {            super(context);            mNorPaint = new Paint();            mNorPaint.setAntiAlias(true);            DisplayMetrics dm = context.getResources().getDisplayMetrics();            int selHeight = cm_DptoPx(2, dm);            int norHeight = cm_DptoPx(1, dm);            mHeight = cm_DptoPx(2, dm);            mNorPaint.setStrokeWidth(norHeight);            mNorPaint.setColor(Color.argb(80, 255, 255, 255));            mSelPaint = new Paint();            mSelPaint.setAntiAlias(true);            mSelPaint.setStrokeWidth(selHeight);            mSelPaint.setColor(Color.WHITE);            mCount = count;            mPadding = cm_DptoPx(0, dm);        }        @Override        protected void onDraw(Canvas canvas) {            super.onDraw(canvas);            int ow = (getWidth()-2*mPadding)/ mCount;            int y = getHeight() / 2;            canvas.drawLine(mPadding, y, mCurPos * ow + mPadding, y, mNorPaint);            canvas.drawLine(mCurPos * ow + mPadding, y, (mCurPos + 1) * ow + mPadding, y, mSelPaint);            canvas.drawLine((mCurPos + 1) * ow + mPadding, y, getWidth() - mPadding, y, mNorPaint);        }        @Override        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {            ViewGroup.LayoutParams vp = getLayoutParams();            vp.width = ViewGroup.LayoutParams.MATCH_PARENT;            vp.height = mHeight;            super.onMeasure(widthMeasureSpec, heightMeasureSpec);        }        public void setCurPostion(int pos) {            mCurPos = pos;            invalidate();        }        public void setCount(int count) {            mCount = count;        }    }}
3、还有MainActivity中的实现

import android.app.Activity;import android.os.Bundle;import android.util.DisplayMetrics;import android.widget.RelativeLayout;public class MainActivity extends Activity {    private RelativeLayout mViewPager;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        DisplayMetrics dm = getResources().getDisplayMetrics();        mViewPager = (RelativeLayout) findViewById(R.id.my_viewpager);        mViewPager.addView(new MyViewPager(getApplicationContext(),dm.widthPixels ,(dm.widthPixels)/2));    }}