前面写过一篇关于下拉刷新控件的文章下拉刷新控件终结者:PullToRefreshLayout,后来看到好多人还有上拉加载更多的需求,于是就在前面下拉刷新控件的基础上进行了改进,加了上拉加载的功能。不仅如此,我已经把它改成了对所有View都通用!可以随心所欲使用这两个功能~~
我做了一个大集合的demo,实现了ListView、GridView、ExpandableListView、ScrollView、WebView、ImageView、TextView的下拉刷新和上拉加载。后面会提供demo的下载地址,最新代码已上传到github:https://github.com/jingchenUSTC/PullToRefreshAndLoad
依照惯例,下面将会是一大波效果图:
demo首页也是可下拉的ListView,在底下可以加入table:
ListView:
GridView:
ExpandableListView:
ScrollView:
WebView:
ImageView:
TextView:
很不错吧?最后的ImageView和TextView是最简单的,直接在下面的接口方法里返回true。
增加上拉加载很简单,和管理下拉头一样,再多管理一个上拉头,也不费事;至于把它改成通用的就需要统一一下View的行为了,为此,我定义了这样一个接口:
package com.jingchen.pulltorefresh.pullableview;
public interface Pullable
{
/**
* 判断是否可以下拉,如果不需要下拉功能可以直接return false
*
* @return true如果可以下拉否则返回false
*/
boolean canPullDown();
/**
* 判断是否可以上拉,如果不需要上拉功能可以直接return false
*
* @return true如果可以上拉否则返回false
*/
boolean canPullUp();
}
从接口名就可以看出它是一个提供判断是否可拉的方法的接口。这个接口的两个方法,canPullDown()是判断何时可以下拉的方法,canPullUp()则是判断何时可以上拉,我在demo中的判断是滑到顶部的时候可以下拉,滑到底部的时候可以上拉。所有需要上拉和下拉的View都需要实现这个接口。后面会给出一些View的实现。先来看看改进后的自定义的布局PullToRefreshLayout,增加了一个上拉头,下拉头和上拉头之间的View是实现了Pullable接口的pullableView。相比前面的版本,这里有改动的需要注意的地方如下:
1、增加了上拉头,相应的也增加了控制变量。
2、拉动时消除content_view事件防止误触发不再使用反射,直接设置 event.setAction(MotionEvent.ACTION_CANCEL)。
3、消除了拉动过程中的多点触碰导致的剧变。
4、不再设置content_view的onTouListener,让使用者可以更加自由的设置监听器。
这个PullToRefreshLayout只负责管理三个控件,如果一个View需要有上拉下拉功能则只需实现接口就行了。下面看PullToRefreshLayout的代码,注释写了好多:
package com.jingchen.pulltorefresh; import java.util.Timer; import java.util.TimerTask; import android.content.Context; import android.graphics.Canvas; import android.graphics.LinearGradient; import android.graphics.Paint; import android.graphics.Paint.Style; import android.graphics.RectF; import android.graphics.Shader.TileMode; import android.os.Handler; import android.os.Message; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.view.animation.LinearInterpolator; import android.view.animation.RotateAnimation; import android.widget.RelativeLayout; import android.widget.TextView; import com.jingchen.pulltorefresh.pullableview.Pullable; /** * 自定义的布局,用来管理三个子控件,其中一个是下拉头,一个是包含内容的pullableView(可以是实现Pullable接口的的任何View), * 还有一个上拉头 * * @author 陈靖 */ public class PullToRefreshLayout extends RelativeLayout { public static final String TAG = "PullToRefreshLayout"; // 初始状态 public static final int INIT = 0; // 释放刷新 public static final int RELEASE_TO_REFRESH = 1; // 正在刷新 public static final int REFRESHING = 2; // 释放加载 public static final int RELEASE_TO_LOAD = 3; // 正在加载 public static final int LOADING = 4; // 操作完毕 public static final int DONE = 5; // 当前状态 private int state = INIT; // 刷新回调接口 private OnRefreshListener mListener; // 刷新成功 public static final int SUCCEED = 0; // 刷新失败 public static final int FAIL = 1; // 按下Y坐标,上一个事件点Y坐标 private float downY, lastY; // 下拉的距离。注意:pullDownY和pullUpY不可能同时不为0 public float pullDownY = 0; // 上拉的距离 private float pullUpY = 0; // 释放刷新的距离 private float refreshDist = 200; // 释放加载的距离 private float loadmoreDist = 200; private MyTimer timer; // 回滚速度 public float MOVE_SPEED = 8; // 第一次执行布局 private boolean isLayout = false; // 在刷新过程中滑动操作 private boolean isTouch = false; // 手指滑动距离与下拉头的滑动距离比,中间会随正切函数变化 private float radio = 2; // 下拉箭头的转180°动画 private RotateAnimation rotateAnimation; // 均匀旋转动画 private RotateAnimation refreshingAnimation; // 下拉头 private View refreshView; // 下拉的箭头 private View pullView; // 正在刷新的图标 private View refreshingView; // 刷新结果图标 private View refreshStateImageView; // 刷新结果:成功或失败 private TextView refreshStateTextView; // 上拉头 private View loadmoreView; // 上拉的箭头 private View pullUpView; // 正在加载的图标 private View loadingView; // 加载结果图标 private View loadStateImageView; // 加载结果:成功或失败 private TextView loadStateTextView; // 实现了Pullable接口的View private View pullableView; // 过滤多点触碰 private int mEvents; // 这两个变量用来控制pull的方向,如果不加控制,当情况满足可上拉又可下拉时没法下拉 private boolean canPullDown = true; private boolean canPullUp = true; /** * 执行自动回滚的handler */ Handler updateHandler = new Handler() { @Override public void handleMessage(Message msg) { // 回弹速度随下拉距离moveDeltaY增大而增大 MOVE_SPEED = (float) (8 + 5 * Math.tan(Math.PI / 2 / getMeasuredHeight() * (pullDownY + Math.abs(pullUpY)))); if (!isTouch) { // 正在刷新,且没有往上推的话则悬停,显示"正在刷新..." if (state == REFRESHING && pullDownY <= refreshDist) { pullDownY = refreshDist; timer.cancel(); } else if (state == LOADING && -pullUpY <= loadmoreDist) { pullUpY = -loadmoreDist; timer.cancel(); } } if (pullDownY > 0) pullDownY -= MOVE_SPEED; else if (pullUpY < 0) pullUpY += MOVE_SPEED; if (pullDownY < 0) { // 已完成回弹 pullDownY = 0; pullView.clearAnimation(); // 隐藏下拉头时有可能还在刷新,只有当前状态不是正在刷新时才改变状态 if (state != REFRESHING && state != LOADING) changeState(INIT); timer.cancel(); } if (pullUpY > 0) { // 已完成回弹 pullUpY = 0; pullUpView.clearAnimation(); // 隐藏下拉头时有可能还在刷新,只有当前状态不是正在刷新时才改变状态 if (state != REFRESHING && state != LOADING) changeState(INIT); timer.cancel(); } // 刷新布局,会自动调用onLayout requestLayout(); } }; public void setOnRefreshListener(OnRefreshListener listener) { mListener = listener; } public PullToRefreshLayout(Context context) { super(context); initView(context); } public PullToRefreshLayout(Context context, AttributeSet attrs) { super(context, attrs); initView(context); } public PullToRefreshLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initView(context); } private void initView(Context context) { timer = new MyTimer(updateHandler); rotateAnimation = (RotateAnimation) AnimationUtils.loadAnimation( context, R.anim.reverse_anim); refreshingAnimation = (RotateAnimation) AnimationUtils.loadAnimation( context, R.anim.rotating); // 添加匀速转动动画 LinearInterpolator lir = new LinearInterpolator(); rotateAnimation.setInterpolator(lir); refreshingAnimation.setInterpolator(lir); } private void hide() { timer.schedule(5); } /** * 完成刷新操作,显示刷新结果。注意:刷新完成后一定要调用这个方法 */ /** * @param refreshResult * PullToRefreshLayout.SUCCEED代表成功,PullToRefreshLayout.FAIL代表失败 */ public void refreshFinish(int refreshResult) { refreshingView.clearAnimation(); refreshingView.setVisibility(View.GONE); switch (refreshResult) { case SUCCEED: // 刷新成功 refreshStateImageView.setVisibility(View.VISIBLE); refreshStateTextView.setText(R.string.refresh_succeed); refreshStateImageView .setBackgroundResource(R.drawable.refresh_succeed); break; case FAIL: default: // 刷新失败 refreshStateImageView.setVisibility(View.VISIBLE); refreshStateTextView.setText(R.string.refresh_fail); refreshStateImageView .setBackgroundResource(R.drawable.refresh_failed); break; } // 刷新结果停留1秒 new Handler() { @Override public void handleMessage(Message msg) { changeState(DONE); hide(); } }.sendEmptyMessageDelayed(0, 1000); } /** * 加载完毕,显示加载结果。注意:加载完成后一定要调用这个方法 * * @param refreshResult * PullToRefreshLayout.SUCCEED代表成功,PullToRefreshLayout.FAIL代表失败 */ public void loadmoreFinish(int refreshResult) { loadingView.clearAnimation(); loadingView.setVisibility(View.GONE); switch (refreshResult) { case SUCCEED: // 加载成功 loadStateImageView.setVisibility(View.VISIBLE); loadStateTextView.setText(R.string.load_succeed); loadStateImageView.setBackgroundResource(R.drawable.load_succeed); break; case FAIL: default: // 加载失败 loadStateImageView.setVisibility(View.VISIBLE); loadStateTextView.setText(R.string.load_fail); loadStateImageView.setBackgroundResource(R.drawable.load_failed); break; } // 刷新结果停留1秒 new Handler() { @Override public void handleMessage(Message msg) { changeState(DONE); hide(); } }.sendEmptyMessageDelayed(0, 1000); } private void changeState(int to) { state = to; switch (state) { case INIT: // 下拉布局初始状态 refreshStateImageView.setVisibility(View.GONE); refreshStateTextView.setText(R.string.pull_to_refresh); pullView.clearAnimation(); pullView.setVisibility(View.VISIBLE); // 上拉布局初始状态 loadStateImageView.setVisibility(View.GONE); loadStateTextView.setText(R.string.pullup_to_load); pullUpView.clearAnimation(); pullUpView.setVisibility(View.VISIBLE); break; case RELEASE_TO_REFRESH: // 释放刷新状态 refreshStateTextView.setText(R.string.release_to_refresh); pullView.startAnimation(rotateAnimation); break; case REFRESHING: // 正在刷新状态 pullView.clearAnimation(); refreshingView.setVisibility(View.VISIBLE); pullView.setVisibility(View.INVISIBLE); refreshingView.startAnimation(refreshingAnimation); refreshStateTextView.setText(R.string.refreshing); break; case RELEASE_TO_LOAD: // 释放加载状态 loadStateTextView.setText(R.string.release_to_load); pullUpView.startAnimation(rotateAnimation); break; case LOADING: // 正在加载状态 pullUpView.clearAnimation(); loadingView.setVisibility(View.VISIBLE); pullUpView.setVisibility(View.INVISIBLE); loadingView.startAnimation(refreshingAnimation); loadStateTextView.setText(R.string.loading); break; case DONE: // 刷新或加载完毕,啥都不做 break; } } /** * 不限制上拉或下拉 */ private void releasePull() { canPullDown = true; canPullUp = true; } /* * (非 Javadoc)由父控件决定是否分发事件,防止事件冲突 * * @see android.view.ViewGroup#dispatchTouchEvent(android.view.MotionEvent) */ @Override public boolean dispatchTouchEvent(MotionEvent ev) { switch (ev.getActionMasked()) { case MotionEvent.ACTION_DOWN: downY = ev.getY(); lastY = downY; timer.cancel(); mEvents = 0; releasePull(); break; case MotionEvent.ACTION_POINTER_DOWN: case MotionEvent.ACTION_POINTER_UP: // 过滤多点触碰 mEvents = -1; break; case MotionEvent.ACTION_MOVE: if (mEvents == 0) { if (((Pullable) pullableView).canPullDown() && canPullDown && state != LOADING) { // 可以下拉,正在加载时不能下拉 // 对实际滑动距离做缩小,造成用力拉的感觉 pullDownY = pullDownY + (ev.getY() - lastY) / radio; if (pullDownY < 0) { pullDownY = 0; canPullDown = false; canPullUp = true; } if (pullDownY > getMeasuredHeight()) pullDownY = getMeasuredHeight(); if (state == REFRESHING) { // 正在刷新的时候触摸移动 isTouch = true; } } else if (((Pullable) pullableView).canPullUp() && canPullUp && state != REFRESHING) { // 可以上拉,正在刷新时不能上拉 pullUpY = pullUpY + (ev.getY() - lastY) / radio; if (pullUpY > 0) { pullUpY = 0; canPullDown = true; canPullUp = false; } if (pullUpY < -getMeasuredHeight()) pullUpY = -getMeasuredHeight(); if (state == LOADING) { // 正在加载的时候触摸移动 isTouch = true; } } else releasePull(); } else mEvents = 0; lastY = ev.getY(); // 根据下拉距离改变比例 radio = (float) (2 + 2 * Math.tan(Math.PI / 2 / getMeasuredHeight() * (pullDownY + Math.abs(pullUpY)))); requestLayout(); if (pullDownY <= refreshDist && (state == RELEASE_TO_REFRESH || state == DONE)) { // 如果下拉距离没达到刷新的距离且当前状态是释放刷新,改变状态为下拉刷新 changeState(INIT); } if (pullDownY >= refreshDist && (state == INIT || state == DONE)) { // 如果下拉距离达到刷新的距离且当前状态是初始状态刷新,改变状态为释放刷新 changeState(RELEASE_TO_REFRESH); } // 下面是判断上拉加载的,同上,注意pullUpY是负值 if (-pullUpY <= loadmoreDist && (state == RELEASE_TO_LOAD || state == DONE)) { changeState(INIT); } if (-pullUpY >= loadmoreDist && (state == INIT || state == DONE)) { changeState(RELEASE_TO_LOAD); } // 因为刷新和加载操作不能同时进行,所以pullDownY和pullUpY不会同时不为0,因此这里用(pullDownY + // Math.abs(pullUpY))就可以不对当前状态作区分了 if ((pullDownY + Math.abs(pullUpY)) > 8) { // 防止下拉过程中误触发长按事件和点击事件 ev.setAction(MotionEvent.ACTION_CANCEL); } break; case MotionEvent.ACTION_UP: if (pullDownY > refreshDist || -pullUpY > loadmoreDist) // 正在刷新时往下拉(正在加载时往上拉),释放后下拉头(上拉头)不隐藏 isTouch = false; if (state == RELEASE_TO_REFRESH) { changeState(REFRESHING); // 刷新操作 if (mListener != null) mListener.onRefresh(this); } else if (state == RELEASE_TO_LOAD) { changeState(LOADING); // 加载操作 if (mListener != null) mListener.onLoadMore(this); } hide(); default: break; } // 事件分发交给父类 super.dispatchTouchEvent(ev); return true; } private void initView() { // 初始化下拉布局 pullView = refreshView.findViewById(R.id.pull_icon); refreshStateTextView = (TextView) refreshView .findViewById(R.id.state_tv); refreshingView = refreshView.findViewById(R.id.refreshing_icon); refreshStateImageView = refreshView.findViewById(R.id.state_iv); // 初始化上拉布局 pullUpView = loadmoreView.findViewById(R.id.pullup_icon); loadStateTextView = (TextView) loadmoreView .findViewById(R.id.loadstate_tv); loadingView = loadmoreView.findViewById(R.id.loading_icon); loadStateImageView = loadmoreView.findViewById(R.id.loadstate_iv); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (!isLayout) { // 这里是第一次进来的时候做一些初始化 refreshView = getChildAt(0); pullableView = getChildAt(1); loadmoreView = getChildAt(2); isLayout = true; initView(); refreshDist = ((ViewGroup) refreshView).getChildAt(0) .getMeasuredHeight(); loadmoreDist = ((ViewGroup) loadmoreView).getChildAt(0) .getMeasuredHeight(); } // 改变子控件的布局,这里直接用(pullDownY + pullUpY)作为偏移量,这样就可以不对当前状态作区分 refreshView.layout(0, (int) (pullDownY + pullUpY) - refreshView.getMeasuredHeight(), refreshView.getMeasuredWidth(), (int) (pullDownY + pullUpY)); pullableView.layout(0, (int) (pullDownY + pullUpY), pullableView.getMeasuredWidth(), (int) (pullDownY + pullUpY) + pullableView.getMeasuredHeight()); loadmoreView.layout(0, (int) (pullDownY + pullUpY) + pullableView.getMeasuredHeight(), loadmoreView.getMeasuredWidth(), (int) (pullDownY + pullUpY) + pullableView.getMeasuredHeight() + loadmoreView.getMeasuredHeight()); } class MyTimer { private Handler handler; private Timer timer; private MyTask mTask; public MyTimer(Handler handler) { this.handler = handler; timer = new Timer(); } public void schedule(long period) { if (mTask != null) { mTask.cancel(); mTask = null; } mTask = new MyTask(handler); timer.schedule(mTask, 0, period); } public void cancel() { if (mTask != null) { mTask.cancel(); mTask = null; } } class MyTask extends TimerTask { private Handler handler; public MyTask(Handler handler) { this.handler = handler; } @Override public void run() { handler.obtainMessage().sendToTarget(); } } } /** * 刷新加载回调接口 * * @author chenjing * */ public interface OnRefreshListener { /** * 刷新操作 */ void onRefresh(PullToRefreshLayout pullToRefreshLayout); /** * 加载操作 */ void onLoadMore(PullToRefreshLayout pullToRefreshLayout); } }
上面就是整个布局的代码,并不是很难。
下面看各个View对Pullable接口的实现,ListView和GridView还有ExpandableListView的判断方法是一样的:
PullableListView:
package com.jingchen.pulltorefresh.pullableview; import android.content.Context; import android.util.AttributeSet; import android.util.Log; import android.widget.ListView; public class PullableListView extends ListView implements Pullable { public PullableListView(Context context) { super(context); } public PullableListView(Context context, AttributeSet attrs) { super(context, attrs); } public PullableListView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override public boolean canPullDown() { if (getCount() == 0) { // 没有item的时候也可以下拉刷新 return true; } else if (getFirstVisiblePosition() == 0 && getChildAt(0).getTop() >= 0) { // 滑到ListView的顶部了 return true; } else return false; } @Override public boolean canPullUp() { if (getCount() == 0) { // 没有item的时候也可以上拉加载 return true; } else if (getLastVisiblePosition() == (getCount() - 1)) { // 滑到底部了 if (getChildAt(getLastVisiblePosition() - getFirstVisiblePosition()) != null && getChildAt( getLastVisiblePosition() - getFirstVisiblePosition()).getBottom() <= getMeasuredHeight()) return true; } return false; } }
PullableExpandableListView:
package com.jingchen.pulltorefresh.pullableview; import android.content.Context; import android.util.AttributeSet; import android.widget.ExpandableListView; public class PullableExpandableListView extends ExpandableListView implements Pullable { public PullableExpandableListView(Context context) { super(context); } public PullableExpandableListView(Context context, AttributeSet attrs) { super(context, attrs); } public PullableExpandableListView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override public boolean canPullDown() { if (getCount() == 0) { // 没有item的时候也可以下拉刷新 return true; } else if (getFirstVisiblePosition() == 0 && getChildAt(0).getTop() >= 0) { // 滑到顶部了 return true; } else return false; } @Override public boolean canPullUp() { if (getCount() == 0) { // 没有item的时候也可以上拉加载 return true; } else if (getLastVisiblePosition() == (getCount() - 1)) { // 滑到底部了 if (getChildAt(getLastVisiblePosition() - getFirstVisiblePosition()) != null && getChildAt( getLastVisiblePosition() - getFirstVisiblePosition()).getBottom() <= getMeasuredHeight()) return true; } return false; } }
PullableGridView:
package com.jingchen.pulltorefresh.pullableview; import android.content.Context; import android.util.AttributeSet; import android.widget.GridView; public class PullableGridView extends GridView implements Pullable { public PullableGridView(Context context) { super(context); } public PullableGridView(Context context, AttributeSet attrs) { super(context, attrs); } public PullableGridView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override public boolean canPullDown() { if (getCount() == 0) { // 没有item的时候也可以下拉刷新 return true; } else if (getFirstVisiblePosition() == 0 && getChildAt(0).getTop() >= 0) { // 滑到顶部了 return true; } else return false; } @Override public boolean canPullUp() { if (getCount() == 0) { // 没有item的时候也可以上拉加载 return true; } else if (getLastVisiblePosition() == (getCount() - 1)) { // 滑到底部了 if (getChildAt(getLastVisiblePosition() - getFirstVisiblePosition()) != null && getChildAt( getLastVisiblePosition() - getFirstVisiblePosition()).getBottom() <= getMeasuredHeight()) return true; } return false; } }
PullableScrollView:
package com.jingchen.pulltorefresh.pullableview; import android.content.Context; import android.util.AttributeSet; import android.widget.ScrollView; public class PullableScrollView extends ScrollView implements Pullable { public PullableScrollView(Context context) { super(context); } public PullableScrollView(Context context, AttributeSet attrs) { super(context, attrs); } public PullableScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override public boolean canPullDown() { if (getScrollY() == 0) return true; else return false; } @Override public boolean canPullUp() { if (getScrollY() >= (getChildAt(0).getHeight() - getMeasuredHeight())) return true; else return false; } }
PullableWebView:
package com.jingchen.pulltorefresh.pullableview; import android.content.Context; import android.util.AttributeSet; import android.webkit.WebView; public class PullableWebView extends WebView implements Pullable { public PullableWebView(Context context) { super(context); } public PullableWebView(Context context, AttributeSet attrs) { super(context, attrs); } public PullableWebView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override public boolean canPullDown() { if (getScrollY() == 0) return true; else return false; } @Override public boolean canPullUp() { if (getScrollY() >= getContentHeight() * getScale() - getMeasuredHeight()) return true; else return false; } }
ImageView和TextView就不贴了,我直接在方法里返回了true。
源码下载:通用版下拉刷新上拉加载大合集demo
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希望本文所述对大家学习Android下拉刷新上拉加载控件有所帮助。