自定義布局實現listview上拉加載下拉刷新

listview布局有時加載數據偏多，需要上拉加載第二頁等更多數據，下拉刷新數據等功能，也有開源的框架XRefreshView ，當初開發項目時，便於自己控制，就自定義布局實現這功能。

1、自定義布局用來管理三個子控件：下拉頭，包含內容的自定義listview，上拉頭（代碼有詳細介紹）

public class PullToRefreshLayout extends RelativeLayout {
    public static final String TAG = "PullToRefreshLayout";
    // 初始狀態
    public static final int INIT = 0;
    // 釋放刷新
    public static final int RELEASE_TO_REFRESH = 1;
    // 正在刷新
    public static final int REFRESHING = 2;
    // 釋放加載
    public static final int RELEASE_TO_LOAD = 3;
    // 正在加載
    public static final int LOADING = 4;
    // 操作完畢
    public static final int DONE = 5;
    // 當前狀態
    private int state = INIT;
    // 刷新回調接口
    private OnRefreshListener mListener;
    // 刷新成功
    public static final int SUCCEED = 0;
    // 刷新失敗
    public static final int FAIL = 1;
    // 按下Y坐標，上一個事件點Y坐標
    private float downY, lastY;

    // 下拉的距離。注意：pullDownY和pullUpY不可能同時不為0
    public float pullDownY = 0;
    // 上拉的距離
    private float pullUpY = 0;

    // 釋放刷新的距離
    private float refreshDist = 200;
    // 釋放加載的距離
    private float loadmoreDist = 200;

    private MyTimer timer;
    // 回滾速度
    public float MOVE_SPEED = 8;
    // 第一次執行布局
    private boolean isLayout = false;
    // 在刷新過程中滑動操作
    private boolean isTouch = false;
    // 手指滑動距離與下拉頭的滑動距離比，中間會隨正切函數變化
    private float radio = 2;

    // 下拉箭頭的轉180°動畫
    private RotateAnimation rotateAnimation;
    // 均勻旋轉動畫
    private RotateAnimation refreshingAnimation;

    // 下拉頭
    private View refreshView;
    // 下拉的箭頭
    private View pullView;
    // 正在刷新的圖標
    private View refreshingView;
    // 刷新結果圖標
    private View refreshStateImageView;
    // 刷新結果：成功或失敗
    private TextView refreshStateTextView;

    // 上拉頭
    private View loadmoreView;
    // 上拉的箭頭
    private View pullUpView;
    // 正在加載的圖標
    private View loadingView;
    // 加載結果圖標
    private View loadStateImageView;
    // 加載結果：成功或失敗
    private TextView loadStateTextView;

    // 實現了Pullable接口的View
    private View pullableView;
    // 過濾多點觸碰
    private int mEvents;
    // 這兩個變量用來控制pull的方向，如果不加控制，當情況滿足可上拉又可下拉時沒法下拉
    private boolean canPullDown = true;
    private boolean canPullUp = true;

    /**
     * 執行自動回滾的handler
     */
    Handler updateHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            // 回彈速度隨下拉距離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，且沒有往上推的話則懸停，顯示"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) {
                // 已完成回彈
                pullDownY = 0;
                pullView.clearAnimation();
                // 隱藏下拉頭時有可能還在刷新，只有當前狀態不是正在刷新時才改變狀態
                if (state != REFRESHING && state != LOADING)
                    changeState(INIT);
                timer.cancel();
            }
            if (pullUpY > 0) {
                // 已完成回彈
                pullUpY = 0;
                pullUpView.clearAnimation();
                // 隱藏下拉頭時有可能還在刷新，只有當前狀態不是正在刷新時才改變狀態
                if (state != REFRESHING && state != LOADING)
                    changeState(INIT);
                timer.cancel();
            }
            // 刷新布局,會自動調用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);
        // 添加勻速轉動動畫
        LinearInterpolator lir = new LinearInterpolator();
        rotateAnimation.setInterpolator(lir);
        refreshingAnimation.setInterpolator(lir);
    }

    private void hide() {
        timer.schedule(5);
    }

    /**
     * 完成刷新操作，顯示刷新結果(注意：刷新完成後一定要調用這個方法)
     *
     * @param refreshResult  PullToRefreshLayout.SUCCEED代表成功，PullToRefreshLayout.FAIL代表失敗
     * void
     *
     */
    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:
            // 刷新失敗
            refreshStateImageView.setVisibility(View.VISIBLE);
            refreshStateTextView.setText(R.string.refresh_fail);
            refreshStateImageView.setBackgroundResource(R.drawable.refresh_failed);
            break;
        }
        // 刷新結果停留1秒
        new Handler() {
            @Override
            public void handleMessage(Message msg) {
                changeState(DONE);
                hide();
            }
        }.sendEmptyMessageDelayed(0, 1000);
    }

    /**
     * 加載完畢，顯示加載結果(注意：加載完成後一定要調用這個方法)
     *
     * @param refreshResult  PullToRefreshLayout.SUCCEED代表成功，PullToRefreshLayout.FAIL代表失敗
     * void
     *
     */
    public void loadmoreFinish(int refreshResult) {
        loadingView.clearAnimation();
        loadingView.setVisibility(View.GONE);
        switch (refreshResult) {
        case SUCCEED:
            // 加載成功
            loadStateImageView.setVisibility(View.VISIBLE);
            loadStateTextView.setText(R.string.load_succeed);
            loadStateImageView.setBackgroundResource(R.drawable.load_succeed);
            break;
        case FAIL:
        default:
            // 加載失敗
            loadStateImageView.setVisibility(View.VISIBLE);
            loadStateTextView.setText(R.string.load_fail);
            loadStateImageView.setBackgroundResource(R.drawable.load_failed);
            break;
        }
        // 刷新結果停留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:
            // 下拉布局初始狀態
            refreshStateImageView.setVisibility(View.GONE);
            refreshStateTextView.setText(R.string.pull_to_refresh);
            pullView.clearAnimation();
            pullView.setVisibility(View.VISIBLE);
            // 上拉布局初始狀態
            loadStateImageView.setVisibility(View.GONE);
            loadStateTextView.setText(R.string.pullup_to_load);
            pullUpView.clearAnimation();
            pullUpView.setVisibility(View.VISIBLE);
            break;
        case RELEASE_TO_REFRESH:
            // 釋放刷新狀態
            refreshStateTextView.setText(R.string.release_to_refresh);
            pullView.startAnimation(rotateAnimation);
            break;
        case REFRESHING:
            // 正在刷新狀態
            pullView.clearAnimation();
            refreshingView.setVisibility(View.VISIBLE);
            pullView.setVisibility(View.INVISIBLE);
            refreshingView.startAnimation(refreshingAnimation);
            refreshStateTextView.setText(R.string.refreshing);
            break;
        case RELEASE_TO_LOAD:
            // 釋放加載狀態
            loadStateTextView.setText(R.string.release_to_load);
            pullUpView.startAnimation(rotateAnimation);
            break;
        case LOADING:
            // 正在加載狀態
            pullUpView.clearAnimation();
            loadingView.setVisibility(View.VISIBLE);
            pullUpView.setVisibility(View.INVISIBLE);
            loadingView.startAnimation(refreshingAnimation);
            loadStateTextView.setText(R.string.loading);
            break;
        case DONE:
            // 刷新或加載完畢，啥都不做
            break;
        }
    }

    /**
     * 不限制上拉或下拉
     */
    private void releasePull() {
        canPullDown = true;
        canPullUp = true;
    }

    @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:
            // 過濾多點觸碰
            mEvents = -1;
            break;
        case MotionEvent.ACTION_MOVE:
            if (mEvents == 0) {
                if (((Pullable) pullableView).canPullDown() && canPullDown
                        && state != LOADING) {
                    // 可以下拉，正在加載時不能下拉
                    // 對實際滑動距離做縮小，造成用力拉的感覺
                    pullDownY = pullDownY + (ev.getY() - lastY) / radio;
                    if (pullDownY < 0) {
                        pullDownY = 0;
                        canPullDown = false;
                        canPullUp = true;
                    }
                    if (pullDownY > getMeasuredHeight())
                        pullDownY = getMeasuredHeight();
                    if (state == REFRESHING) {
                        // 正在刷新的時候觸摸移動
                        isTouch = true;
                    }
                } else if (((Pullable) pullableView).canPullUp() && canPullUp
                        && state != REFRESHING) {
                    // 可以上拉，正在刷新時不能上拉
                    pullUpY = pullUpY + (ev.getY() - lastY) / radio;
                    if (pullUpY > 0) {
                        pullUpY = 0;
                        canPullDown = true;
                        canPullUp = false;
                    }
                    if (pullUpY < -getMeasuredHeight())
                        pullUpY = -getMeasuredHeight();
                    if (state == LOADING) {
                        // 正在加載的時候觸摸移動
                        isTouch = true;
                    }
                } else
                    releasePull();
            } else
                mEvents = 0;
            lastY = ev.getY();
            // 根據下拉距離改變比例
            radio = (float) (2 + 2 * Math.tan(Math.PI / 2 / getMeasuredHeight()
                    * (pullDownY + Math.abs(pullUpY))));
            requestLayout();
            if (pullDownY <= refreshDist && state == RELEASE_TO_REFRESH) {
                // 如果下拉距離沒達到刷新的距離且當前狀態是釋放刷新，改變狀態為下拉刷新
                changeState(INIT);
            }
            if (pullDownY >= refreshDist && state == INIT) {
                // 如果下拉距離達到刷新的距離且當前狀態是初始狀態刷新，改變狀態為釋放刷新
                changeState(RELEASE_TO_REFRESH);
            }
            // 下面是判斷上拉加載的，同上，注意pullUpY是負值
            if (-pullUpY <= loadmoreDist && state == RELEASE_TO_LOAD) {
                changeState(INIT);
            }
            if (-pullUpY >= loadmoreDist && state == INIT) {
                changeState(RELEASE_TO_LOAD);
            }
            // 因為刷新和加載操作不能同時進行，所以pullDownY和pullUpY不會同時不為0，因此這裡用(pullDownY +
            // Math.abs(pullUpY))就可以不對當前狀態作區分了
            if ((pullDownY + Math.abs(pullUpY)) > 8) {
                // 防止下拉過程中誤觸發長按事件和點擊事件
                ev.setAction(MotionEvent.ACTION_CANCEL);
            }
            break;
        case MotionEvent.ACTION_UP:
            if (pullDownY > refreshDist || -pullUpY > loadmoreDist)
                // 正在刷新時往下拉（正在加載時往上拉），釋放後下拉頭（上拉頭）不隱藏
                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);
                // 加載操作
                if (mListener != null)
                    mListener.onLoadMore(this);
            }
            hide();
        default:
            break;
        }
        // 事件分發交給父類
        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) {
            // 這裡是第一次進來的時候做一些初始化
            refreshView = getChildAt(0);
            pullableView = getChildAt(1);
            loadmoreView = getChildAt(2);
            isLayout = true;
            initView();
            refreshDist = ((ViewGroup) refreshView).getChildAt(0).getMeasuredHeight();
            loadmoreDist = ((ViewGroup) loadmoreView).getChildAt(0).getMeasuredHeight();
        }
        // 改變子控件的布局，這裡直接用(pullDownY + pullUpY)作為偏移量，這樣就可以不對當前狀態作區分
        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();
            }

        }
    }

    /**
     * 刷新加載回調接口
     */
    public interface OnRefreshListener {
        /**
         * 刷新操作
         */
        void onRefresh(PullToRefreshLayout pullToRefreshLayout);

        /**
         * 加載操作
         */
        void onLoadMore(PullToRefreshLayout pullToRefreshLayout);
    }

}

2、定義上拉下拉的事件的接口

public interface Pullable {

    /**
     * 判斷是否可以下拉，如果不需要下拉功能可以直接return false
     *
     * @創建日期 2015年10月19日
     *
     * @return boolean true如果可以下拉否則返回false
     */
    boolean canPullDown();

    /**
     * 判斷是否可以上拉，如果不需要上拉功能可以直接return false
     *
     * @創建日期 2015年10月19日
     *
     * @return boolean  true如果可以上拉否則返回false
     * 
     */
    boolean canPullUp();
}

3、自定義listview實現上拉下拉的事件操作

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) { // 沒有item的時候也可以下拉刷新
            return true;
        } else if (getFirstVisiblePosition() == 0
                && getChildAt(0).getTop() >= 0) {
            // 滑到ListView的頂部
            return true;
        } else{
            return false;
        }
    }

    @Override
    public boolean canPullUp() {
        if (getCount() == 0) { // 沒有item的時候也可以上拉加載
            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;
    }
}

4、布局

其中上拉和下拉的布局是分開引入的，自己可以根據樣式自定義

5、調用

先獲取自定義布局,實現自定義的刷新方法

((PullToRefreshLayout) findViewById(R.id.project_refresh_view)).setOnRefreshListener(new MyClickListener());

class MyClickListener implements OnRefreshListener {
        /**
         * 下拉刷新操作
         */
        @Override
        public void onRefresh(final PullToRefreshLayout pullToRefreshLayout) {

            new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    pullToRefreshLayout.refreshFinish(PullToRefreshLayout.SUCCEED);
                    onDestroy();
                }
            }.sendEmptyMessageDelayed(0, 1000);
        }

        /**
         * 上拉加載更多操作
         */
        @Override
        public void onLoadMore(final PullToRefreshLayout pullToRefreshLayout) {
            new Handler() {
                @Override
                public void handleMessage(Message msg) {

                    //獲取更多數據的方法
                    loadProjectPost(signUrl);
                            pullToRefreshLayout.loadmoreFinish(PullToRefreshLayout.SUCCEED);
                }
            }.sendEmptyMessageDelayed(0, 1000);
        }

    }