android使用ViewPager实现图片自动切换

本文实现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

因为我的ViewPager是继承RelativeLayout

2、layout_recommend_item.xml中的布局

ImageView是显示图片 TextView用来显示每一个pager的标题

3、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 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;
    }
  }
}

4、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));
  }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。