• Android下拉刷新上拉载入控件,对全部View通用!


        转载请声明出处http://blog.csdn.net/zhongkejingwang/article/details/38868463

         前面写过一篇关于下拉刷新控件的博客下拉刷新控件终结者:PullToRefreshLayout,后来看到好多人还有上拉载入很多其它的需求,于是就在前面下拉刷新控件的基础上进行了改进,加了上拉载入的功能。不仅如此,我已经把它改成了对全部View都通用!能够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的下拉刷新和上拉载入。后面会提供demo的下载地址。(csdn上的demo有小bug,最新代码已上传到github:https://github.com/jingchenUSTC/PullToRefreshAndLoad)

        按照惯例,以下将会是一大波效果图:

    demo首页也是可下拉的ListView,在底下能够增加table:

                                                

    ListView:

                    

    GridView:

                    

    ExpandableListView:

                    

    ScrollView:

                   

    WebView:

                   

    ImageView:

                    

    TextView:

                    

        非常不错吧?最后的ImageView和TextView是最简单的,直接在以下的接口方法里返回true。

        添加上拉载入非常easy,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须要统一一下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
    {
    	/**
    	 * 推断能否够下拉,假设不须要下拉功能能够直接return false
    	 * 
    	 * @return true假设能够下拉否则返回false
    	 */
    	boolean canPullDown();
    
    	/**
    	 * 推断能否够上拉,假设不须要上拉功能能够直接return false
    	 * 
    	 * @return true假设能够上拉否则返回false
    	 */
    	boolean canPullUp();
    }
    
    从接口名就能够看出它是一个提供推断是否可拉的方法的接口。这个接口的两个方法,canPullDown()是推断何时能够下拉的方法,canPullUp()则是推断何时能够上拉,我在demo中的推断是滑到顶部的时候能够下拉,滑究竟部的时候能够上拉。全部须要上拉和下拉的View都须要实现这个接口。后面会给出一些View的实现。先来看看改进后的自己定义的布局PullToRefreshLayout,添加了一个上拉头,下拉头和上拉头之间的View是实现了Pullable接口的pullableView。相比前面的版本号,这里有修改的须要注意的地方例如以下:

    1、添加了上拉头,对应的也添加了控制变量。

    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,让使用者能够更加自由的设置监听器。

       这个PullToRefreshLayout仅仅负责管理三个控件,假设一个View须要有上拉下拉功能则仅仅需实现接口即可了。以下看PullToRefreshLayout的代码,凝视写了好多:

    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;
    
    /**
     * 自己定义的布局,用来管理三个子控件,当中一个是下拉头,一个是包括内容的pullableView(能够是实现Pullable接口的的不论什么View),
     * 另一个上拉头
     * 
     * @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;
    	// 释放载入
    	public static final int RELEASE_TO_LOAD = 3;
    	// 正在载入
    	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不可能同一时候不为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;
    	// 释放载入的距离
    	private float loadmoreDist = 200;
    
    	private MyTimer timer;
    	// 回滚速度
    	public float MOVE_SPEED = 8;
    	// 第一次运行布局
    	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;
    	// 正在载入的图标
    	private View loadingView;
    	// 载入结果图标
    	private View loadStateImageView;
    	// 载入结果: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,假设不加控制,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;
    
    	/**
    	 * 运行自己主动回滚的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)
    			{
    				// 已完毕回弹
    				pullDownY = 0;
    				pullView.clearAnimation();
    				// 隐藏下拉头时有可能还在刷新,仅仅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)
    			{
    				// 已完毕回弹
    				pullUpY = 0;
    				pullUpView.clearAnimation();
    				// 隐藏下拉头时有可能还在刷新,仅仅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,会自己主动调用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);
    		// 加入匀速转动动画
    		LinearInterpolator lir = new LinearInterpolator();
    		rotateAnimation.setInterpolator(lir);
    		refreshingAnimation.setInterpolator(lir);
    	}
    
    	private void hide()
    	{
    		timer.schedule(5);
    	}
    
    	/**
    	 * 完毕刷新操作,显示刷新结果。注意:刷新完毕后一定要调用这种方法
    	 */
    	/**
    	 * @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);
    	}
    
    	/**
    	 * 载入完毕,显示载入结果。注意:载入完毕后一定要调用这种方法
    	 * 
    	 * @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:
    			// 载入成功
    			loadStateImageView.setVisibility(View.VISIBLE);
    			loadStateTextView.setText(R.string.load_succeed);
    			loadStateImageView.setBackgroundResource(R.drawable.load_succeed);
    			break;
    		case FAIL:
    		default:
    			// 载入失败
    			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:
    			// 释放载入状态
    			loadStateTextView.setText(R.string.release_to_load);
    			pullUpView.startAnimation(rotateAnimation);
    			break;
    		case LOADING:
    			// 正在载入状态
    			pullUpView.clearAnimation();
    			loadingView.setVisibility(View.VISIBLE);
    			pullUpView.setVisibility(View.INVISIBLE);
    			loadingView.startAnimation(refreshingAnimation);
    			loadStateTextView.setText(R.string.loading);
    			break;
    		case DONE:
    			// 刷新或载入完毕,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)
    				{
    					// 能够下拉,正在载入时不能下拉
    					// 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)
    				{
    					// 能够上拉,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)
    					{
    						// 正在载入的时候触摸移动
    						isTouch = true;
    					}
    				} else
    					releasePull();
    			} else
    				mEvents = 0;
    			lastY = ev.getY();
    			// 依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
    <span style="white-space:pre">					</span>&& (state == RELEASE_TO_REFRESH || state == DONE)) {
    <span style="white-space:pre">				</span>// 假设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
    <span style="white-space:pre">				</span>changeState(INIT);
    <span style="white-space:pre">			</span>}
    <span style="white-space:pre">			</span>if (pullDownY >= refreshDist && (state == INIT || state == DONE)) {
    <span style="white-space:pre">				</span>// 假设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
    <span style="white-space:pre">				</span>changeState(RELEASE_TO_REFRESH);
    <span style="white-space:pre">			</span>}
    <span style="white-space:pre">			</span>// 以下是推断上拉载入的,同上,注意pullUpY是负值
    <span style="white-space:pre">			</span>if (-pullUpY <= loadmoreDist
    <span style="white-space:pre">					</span>&& (state == RELEASE_TO_LOAD || state == DONE)) {
    <span style="white-space:pre">				</span>changeState(INIT);
    <span style="white-space:pre">			</span>}
    <span style="white-space:pre">			</span>if (-pullUpY >= loadmoreDist && (state == INIT || state == DONE)) {
    <span style="white-space:pre">				</span>changeState(RELEASE_TO_LOAD);
    <span style="white-space:pre">			</span>}
    			// 由于刷新和载入操作不能同一时候进行,所以pullDownY和pullUpY不会同一时候不为0,因此这里用(pullDownY +
    			// Math.abs(pullUpY))就能够不正确当前状态作区分了
    			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(正在载入时往上拉),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);
    				// 载入操作
    				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,这样就能够不正确当前状态作区分
    		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();
    			}
    
    		}
    	}
    
    	/**
    	 * 刷新载入回调接口
    	 * 
    	 * @author chenjing
    	 * 
    	 */
    	public interface OnRefreshListener
    	{
    		/**
    		 * 刷新操作
    		 */
    		void onRefresh(PullToRefreshLayout pullToRefreshLayout);
    
    		/**
    		 * 载入操作
    		 */
    		void onLoadMore(PullToRefreshLayout pullToRefreshLayout);
    	}
    
    }
    
    上面就是整个布局的代码,并非非常难。

    以下看各个View对Pullable接口的实现,ListView和GridView还有ExpandableListView的推断方法是一样的:

    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的时候也能够下拉刷新
    			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的时候也能够上拉载入
    			return true;
    		} else if (getLastVisiblePosition() == (getCount() - 1))
    		{
    			// 滑究竟部了
    			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的时候也能够下拉刷新
    			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的时候也能够上拉载入
    			return true;
    		} else if (getLastVisiblePosition() == (getCount() - 1))
    		{
    			// 滑究竟部了
    			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的时候也能够下拉刷新
    			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的时候也能够上拉载入
    			return true;
    		} else if (getLastVisiblePosition() == (getCount() - 1))
    		{
    			// 滑究竟部了
    			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。

    OK了,整个demo的代码有点多,就不贴了。

    源代码下载


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  • 原文地址:https://www.cnblogs.com/hrhguanli/p/4508104.html
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