Android实践之带加载效果的下拉刷新上拉加载更多

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package top.greendami.greendami;
package com.allrun.arsmartelevatorformanager.widget;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.TextView;
import com.allrun.arsmartelevatorformanager.R;
import com.allrun.arsmartelevatorformanager.util.DPUnitUtil;
/**
 * Created by GreendaMI on 2017/3/21.
 */
public class PPRefreshView extends ViewGroup {
 Context context;
 RecyclerView mListView;
 PPView mPPView;
 View header;
 TextView title;
 ImageView mImage;//箭头
 int listTop = 0;
 float headerHeight = 10 + 30 + 10;//header的高度，上留白 + 文字（PPVIew）高度 + 下留白
 float headerpadding = 10;//上留白,下留白
 private int mYDown, mLastY;
 //最短滑动距离
 int a = 0;
 RotateAnimation mRotateAnimation;
 int state = 0; //0,正常;1,下拉;2,松开
 public void setPPRefreshViewListener(PPRefreshViewListener mPPRefreshViewListener) {
 this.mPPRefreshViewListener = mPPRefreshViewListener;
 }
 PPRefreshViewListener mPPRefreshViewListener;
 public PPRefreshView(Context context) {
 super(context);
 this.cOntext= context;
 }
 public PPRefreshView(Context context, AttributeSet attrs) {
 super(context, attrs);
 this.cOntext= context;
 //px转dp
 a = DPUnitUtil.px2dip(context,ViewConfiguration.get(context).getScaledDoubleTapSlop());
 TypedArray b = context.obtainStyledAttributes(attrs, R.styleable.PPRefreshView_header);
 headerHeight = b.getDimension(R.styleable.PPRefreshView_header_header_height, 100);
 headerpadding = b.getDimension(R.styleable.PPRefreshView_header_header_padding, 10);
 b.recycle();
 initAnima();
 }
 private void initAnima() {
 //箭头旋转
 mRotateAnimation = new RotateAnimation(0, 180, Animation.RELATIVE_TO_SELF,
 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 mRotateAnimation.setFillAfter(true);
 mRotateAnimation.setDuration(200);
 }
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 if (mPPView != null) {
 mPPView.measure(widthMeasureSpec,(int) (headerHeight- 2 * headerpadding));
 }
 if (header != null) {
 header.measure(widthMeasureSpec, (int) (headerHeight- 2 * headerpadding));
 }
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 }
 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
 if (mListView == null && getChildCount() == 1) {
 mListView = (RecyclerView)getChildAt(0);
 mListView.setOnScrollListener(new RecyclerView.OnScrollListener() {
 @Override
 public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
  super.onScrolled(recyclerView, dx, dy);
  if(!recyclerView.canScrollVertically(1)){
  //添加外部回调
  if(mPPRefreshViewListener != null){  mPPRefreshViewListener.LoadMore();
  }
  }
 }
 });
 }
 if (mListView != null) {
 mListView.layout(l, listTop, getMeasuredWidth(), b);
 }
 if (mPPView != null) {
 //top：文字（PPVIew）高度 + 下留白
 mPPView.layout(l, (int)(listTop - headerHeight + headerpadding), r, listTop);
 }
 if (header != null) {
 //top：文字（PPView）高度 + 下留白
 header.layout(l, (int)(listTop - headerHeight + headerpadding), r, listTop);
 }
 }
 @Override
 protected void dispatchDraw(Canvas canvas) {
 super.dispatchDraw(canvas);
 //松开手指，list回到顶部
 if (state == 2) {
 listTop = listTop - 25;
 if (listTop  0) {
 listTop = listTop - 25;
 if (listTop <0) {
 listTop = 0;
 }
 requestLayout();
 }
 }
 @Override
 public boolean dispatchTouchEvent(MotionEvent event) {
 final int action = event.getAction();
 switch (action) {
 case MotionEvent.ACTION_DOWN:
 // 按下
 mYDown = (int) event.getRawY();
 break;
 case MotionEvent.ACTION_MOVE:
 // 移动
 mLastY = (int) event.getRawY();
 if (!mListView.canScrollVertically(-1) && mLastY > mYDown &&(mLastY - mYDown) > a) {
  state = 1;
  listTop = mLastY - mYDown;
  if (mPPView != null) {
  removeView(mPPView);
  mPPView = null;
  }
  if (header == null) {
  header = LayoutInflater.from(context).inflate(R.layout.header_layout, null, false);
  title = ((TextView) header.findViewById(R.id.text));
  mImage = ((ImageView) header.findViewById(R.id.icon));
  addView(header);
  }
  if (title != null && (mLastY - mYDown) > a * 2f) {
  title.setText("松开刷新");
  if (mImage.getAnimation() == null) {
  mImage.startAnimation(mRotateAnimation);
  }
  }
  if (title != null && (mLastY - mYDown)