基于RecyclerView通用适配自定义下拉刷新

天气热，人也变的懒散了，晚上如汗蒸，睡眠很不好，精神状态也不好。

一、前言

自从使用了RecyclerView，就爱上了它，灵活性非常的强大，效果绚丽，如果想进一步了解，请关注：

RecyclerView 之通用适配

在通用适配篇中使用的SwipeRefreshLayout实现的下拉刷新功能，本篇带大家实现自定义的下拉刷新，先来啾啾效果图：

PullRefreshLoadView（下拉刷新）

PullRefreshLoadView下拉控件有4个状态，分别是：

• STATE_PULL_TO_REFRESH 下拉刷新状态

• STATE_RELEASE_TO_REFRESH 释放立即刷新状态

• STATE_REFRESHING 正在刷新状态

• STATE_REFRESHED 刷新完成状态

实现的原理：重写RecyclerView的onTouchEvent方法，获取getRawY差值动态计算PullRefreshLoadView的高度。

原理还是比较简单的，但这里有2点你需要注意：

1、setVisibility(View.INVISIBLE)无效，在刷新状态的时需要对箭头图标进行隐藏，发现View.INVISIBLE不管用，这个就纠结了，网上几乎找不到这方面的问题，后来看到一篇文章就说加一句clearAnimation();靠，还真解决了：

mArrowIv.clearAnimation();mArrowIv.setVisibility(View.INVISIBLE);

2、无限循环动画的匿名updatelistener里面直接执行invalidate方法，由于对view的强引用，导致view无法被正常回收，进一步导致view的context的activity无法被回收，最终产生内存泄露。解决方案就是重写一个updatelistener，在构造函数中实现对view的弱引用：

private static class MyUpdateListener implements ValueAnimator.AnimatorUpdateListener {    private WeakReference<BallSpinFadeLoader> mWeakReference;    public MyUpdateListener(BallSpinFadeLoader ballSpinFadeLoader) {        mWeakReference = new WeakReference<BallSpinFadeLoader>(ballSpinFadeLoader);    }    @Override    public void onAnimationUpdate(ValueAnimator valueAnimator) {        BallSpinFadeLoader ball = mWeakReference.get();        if (ball == null) {            return;        }    }}

下面是PullRefreshLoadView源码：

package com.github.baserecycleradapter.widget;import android.animation.ValueAnimator;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.Gravity;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.view.animation.Animation;import android.view.animation.RotateAnimation;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.TextView;import com.github.baserecycleradapter.R;/** * Created by Administrator on 8/24 0024. */public class PullRefreshLoadView extends LinearLayout {    private Context mContext; //上下文    private LinearLayout mContainer;    private ImageView mArrowIv;  //箭头    private TextView mStatusTv;  //下拉刷新  释放刷新  刷新完成    private BallSpinFadeLoader mLoader;  //loading 图标    private int mState;     //状态    private int mHeight;  //高度    private Animation mArrowDownAnim;//向下动画    private Animation mArrowUpAnim;  //向上动画    public final static int STATE_PULL_TO_REFRESH = 0;    public final static int STATE_RELEASE_TO_REFRESH = 1;    public final static int STATE_REFRESHING = 2;    public final static int STATE_REFRESHED = 3;    public final static String PULL_TO_REFRESH = "下拉刷新";    public final static String RELEASE_TO_REFRESH = "释放立即刷新";    public final static String REFRESHING = "正在刷新...";    public final static String REFRESHED = "刷新完成";    public PullRefreshLoadView(Context context) {        this(context, null);    }    public PullRefreshLoadView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public PullRefreshLoadView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initView(context);    }    private void initView(Context context) {        mContext = context;        mState = STATE_PULL_TO_REFRESH;        mContainer = (LinearLayout) LayoutInflater.from(getContext()).inflate(                R.layout.rv_refresh, null);        LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);        lp.setMargins(0, 0, 0, 0);        setLayoutParams(lp);        setPadding(0, 0, 0, 0);        addView(mContainer, new LayoutParams(LayoutParams.MATCH_PARENT, 0));        setGravity(Gravity.BOTTOM);        mArrowIv = (ImageView) mContainer.findViewById(R.id.iv_arrow);        mStatusTv = (TextView) mContainer.findViewById(R.id.tv_refresh_status);        mLoader = (BallSpinFadeLoader) mContainer.findViewById(R.id.ball_loader);        mArrowDownAnim = new RotateAnimation(180.0f, 0.0f,                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);        mArrowDownAnim.setDuration(180);        mArrowDownAnim.setFillAfter(true);        mArrowUpAnim = new RotateAnimation(0.0f, 180.0f,                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);        mArrowUpAnim.setDuration(180);        mArrowUpAnim.setFillAfter(true);        measure(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);        mHeight = getMeasuredHeight();    }    /**     * @param resId     */    public void setArrowImageView(int resId) {        if (mArrowIv != null) {            mArrowIv.setImageResource(resId);        }    }    public int getState() {        return mState;    }    public int getVisibleHeight() {        LayoutParams lp = (LayoutParams) mContainer.getLayoutParams();        return lp.height;    }    public void setVisibleHeight(int height) {        if (height <= 0)            height = 0;        LayoutParams lp = (LayoutParams) mContainer.getLayoutParams();        lp.height = height;        mContainer.setLayoutParams(lp);    }    public void refreshComplete() {        setState(STATE_REFRESHED);        reset();    }    /**     * @param delta     */    public void onMove(float delta) {        if (getVisibleHeight() > 0 || delta > 0) {            setVisibleHeight((int) (delta + getVisibleHeight()));            if (mState <= STATE_RELEASE_TO_REFRESH) {                if (getVisibleHeight() > mHeight) {                    setState(STATE_RELEASE_TO_REFRESH);                } else {                    setState(STATE_PULL_TO_REFRESH);                }            }        }    }    public boolean releaseAction() {        boolean isOnRefresh = false;        int height = getVisibleHeight();        int destHeight = 0;        if (height == 0) isOnRefresh = false;        if (mState == STATE_REFRESHING) {            destHeight = mHeight;        }        if (height > mHeight && mState < STATE_REFRESHING) {            setState(STATE_REFRESHING);            destHeight = mHeight;            isOnRefresh = true;        }        smoothScrollTo(destHeight);        return isOnRefresh;    }    public void reset() {        smoothScrollTo(0);        postDelayed(new Runnable() {            @Override            public void run() {                setState(STATE_PULL_TO_REFRESH);            }        }, 200);    }    /**     * @param state     */    public void setState(int state) {        if (state == mState)            return;        if (state == STATE_REFRESHING) {            if (!mLoader.isLoading()) {                mLoader.startAnimator();            }            mArrowIv.clearAnimation();            mStatusTv.setText(REFRESHING);            mLoader.setVisibility(View.VISIBLE);            mArrowIv.setVisibility(View.INVISIBLE);        } else if (state == STATE_PULL_TO_REFRESH) {            mArrowIv.setVisibility(View.VISIBLE);            mLoader.setVisibility(View.INVISIBLE);            mStatusTv.setText(PULL_TO_REFRESH);            if (mState == STATE_RELEASE_TO_REFRESH) {                mArrowIv.startAnimation(mArrowDownAnim);            } else if (mState == STATE_REFRESHING) {                mArrowIv.clearAnimation();            }        } else if (state == STATE_RELEASE_TO_REFRESH) {            mArrowIv.setVisibility(View.VISIBLE);            mLoader.setVisibility(View.INVISIBLE);            mStatusTv.setText(RELEASE_TO_REFRESH);            if (mState != STATE_RELEASE_TO_REFRESH) {                mArrowIv.clearAnimation();                mArrowIv.startAnimation(mArrowUpAnim);            }        } else if (state == STATE_REFRESHED) {            mArrowIv.clearAnimation();            mStatusTv.setText(REFRESHED);            mArrowIv.setVisibility(View.INVISIBLE);            mLoader.setVisibility(View.INVISIBLE);        }        mState = state;    }    /**     * @param destHeight     */    private void smoothScrollTo(int destHeight) {        ValueAnimator animator = ValueAnimator.ofInt(getVisibleHeight(), destHeight);        animator.setDuration(300).start();        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {            @Override            public void onAnimationUpdate(ValueAnimator animation) {                setVisibleHeight((int) animation.getAnimatedValue());            }        });        animator.start();    }}

接着来看看RecyclerView的onTouchEvent方法：

@Overridepublic boolean onTouchEvent(MotionEvent e) {    if (mLastY == -1) {        mLastY = e.getRawY();    }    switch (e.getAction()) {        case MotionEvent.ACTION_DOWN:            mLastY = e.getRawY();            break;        case MotionEvent.ACTION_MOVE:            if (isScrollTop()) {                float deltaY = e.getRawY() - mLastY;                mPullRefreshLoadView.onMove(deltaY / 3);                mLastY = e.getRawY();                if (mPullRefreshLoadView.getVisibleHeight() > 0 &&                        mPullRefreshLoadView.getState() < mPullRefreshLoadView.STATE_REFRESHING) {                    return false;                }            }            break;        default:        case MotionEvent.ACTION_UP:        case MotionEvent.ACTION_CANCEL:        case MotionEvent.ACTION_OUTSIDE:            mLastY = -1; // reset            if (mPullRefreshLoadView.releaseAction()) {                if (mCompleteListener != null) {                    mCompleteListener.onRefreshComplete();                }            }            break;    }    return super.onTouchEvent(e);}

源码地址，如果你喜欢，还请 star