Android下拉刷新上拉加载控件，对所有View通用！ – Android移动开发技术文章_手机开发 – 红黑联盟

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。

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：

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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：

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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)
            {
                // 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)
            {
                // 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)
            {
                changeState(INIT);
            }
            if (-pullUpY >= loadmoreDist && state == INIT)
            {
                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。

OK了，整个demo的代码有点多，就不贴了。

源码下载

来源URL：http://www.2cto.com/kf/201408/329317.html