Android 自定义下拉刷新ListView

package com.dwtedx.qq.view;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;

import com.dwtedx.tst.R;

public class DropdownListView extends ListView implements OnScrollListener {

    private static final String TAG = "listview";

    private final static int RELEASE_To_REFRESH = 0;
    private final static int PULL_To_REFRESH = 1;
    private final static int REFRESHING = 2;
    private final static int DONE = 3;
    private final static int LOADING = 4;

    // 实际的padding的距离与界面上偏移距离的比例
    private final static int RATIO = 3;

    private LayoutInflater inflater;
    private FrameLayout fl;
    private LinearLayout headView;

//    private View line;
    private ProgressBar progressBar;

//    private RotateAnimation animation;
//    private RotateAnimation reverseAnimation;

    // 用于保证startY的值在一个完整的touch事件中只被记录一次
    private boolean isRecored;

    private int headContentWidth;
    private int headContentHeight;

    private int startY;
    private int firstItemIndex;

    private int state;

    private boolean isBack;

    private OnRefreshListenerHeader refreshListenerHeader;


    private boolean isRefreshableHeader;

    
    public DropdownListView(Context context) {
        super(context);
        init(context);
    }

    public DropdownListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    private void init(Context context) {
        setCacheColorHint(context.getResources().getColor(R.color.transparent));
        inflater = LayoutInflater.from(context);
        
        fl = (FrameLayout)inflater.inflate(R.layout.dropdown_lv_head, null);
        headView = (LinearLayout) fl.findViewById(R.id.drop_down_head);

        progressBar = (ProgressBar) fl.findViewById(R.id.loading);
        measureView(headView);
        
        
        headContentHeight = headView.getMeasuredHeight();
        headContentWidth = headView.getMeasuredWidth();

        headView.setPadding(0, -1 * headContentHeight, 0, 0);
        headView.invalidate();

        Log.v("size", "" + headContentWidth + " height:"
                + headContentHeight);

        addHeaderView(fl, null, false);
//        addHeaderView(headView, null, false);
        setOnScrollListener(this);


        state = DONE;
        isRefreshableHeader = false;
    }

    public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2,
            int arg3) {
        firstItemIndex = firstVisiableItem;
    }

    public void onScrollStateChanged(AbsListView arg0, int scrollState) {
        if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
            // 判断滚动到底部

        }
    }

    public boolean onTouchEvent(MotionEvent event) {

        if (isRefreshableHeader) {
            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                if (firstItemIndex == 0 && !isRecored) {
                    isRecored = true;
                    startY = (int) event.getY();
                    Log.v(TAG, "在down时候记录当前位置‘");
                }
                break;

            case MotionEvent.ACTION_UP:

                if (state != REFRESHING && state != LOADING) {
                    if (state == DONE) {
                        // 什么都不做
                    }
                    if (state == PULL_To_REFRESH) {
                        state = DONE;
                        changeHeaderViewByState();

                        Log.v(TAG, "由下拉刷新状态，到done状态");
                    }
                    if (state == RELEASE_To_REFRESH) {
                        state = REFRESHING;
                        
                        changeHeaderViewByState();
//                        recoverLine();
                        onRefresh();
                        
                        Log.v(TAG, "由松开刷新状态，到done状态");
                    }
                }

                isRecored = false;
                isBack = false;

                break;

            case MotionEvent.ACTION_MOVE:
                int tempY = (int) event.getY();
                if (!isRecored && firstItemIndex == 0) {
                    Log.v(TAG, "在move时候记录下位置");
                    isRecored = true;
                    startY = tempY;
                }

                if (state != REFRESHING && isRecored && state != LOADING) {

                    // 保证在设置padding的过程中，当前的位置一直是在head，否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动

                    // 可以松手去刷新了
                    if (state == RELEASE_To_REFRESH) {

                        setSelection(0);

                        // 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步
                        if (((tempY - startY) / RATIO < headContentHeight)
                                && (tempY - startY) > 0) {
                            state = PULL_To_REFRESH;
                            changeHeaderViewByState();

                            Log.v(TAG, "由松开刷新状态转变到下拉刷新状态");
                        }
                        // 一下子推到顶了
                        else if (tempY - startY <= 0) {
                            state = DONE;
                            changeHeaderViewByState();

                            Log.v(TAG, "由松开刷新状态转变到done状态");
                        }
                        // 往下拉了，或者还没有上推到屏幕顶部掩盖head的地步
                        else {
                            // 不用进行特别的操作，只用更新paddingTop的值就行了
                        }
                    }
                    // 还没有到达显示松开刷新的时候,DONE或者是PULL_To_REFRESH状态
                    if (state == PULL_To_REFRESH) {

                        setSelection(0);

                        // 下拉到可以进入RELEASE_TO_REFRESH的状态
                        if ((tempY - startY) / RATIO >= headContentHeight) {
                            state = RELEASE_To_REFRESH;
                            isBack = true;
                            changeHeaderViewByState();

                            Log.v(TAG, "由done或者下拉刷新状态转变到松开刷新");
                        }
                        // 上推到顶了
                        else if (tempY - startY <= 0) {
                            state = DONE;
                            changeHeaderViewByState();

                            Log.v(TAG, "由DOne或者下拉刷新状态转变到done状态");
                        }
                    }

                    // done状态下
                    if (state == DONE) {
                        if (tempY - startY > 0) {
                            state = PULL_To_REFRESH;
                            changeHeaderViewByState();
                        }
                    }

                    // 更新headView的size
                    if (state == PULL_To_REFRESH) {
                        headView.setPadding(0, -1 * headContentHeight
                                + (tempY - startY) / RATIO, 0, 0);
                    }

                    // 更新headView的paddingTop
                    if (state == RELEASE_To_REFRESH) {
                        headView.setPadding(0, (tempY - startY) / RATIO
                                - headContentHeight, 0, 0);
                    }
                }

                break;
            }
        }

        return super.onTouchEvent(event);
    }

    // 当状态改变时候，调用该方法，以更新界面
    private void changeHeaderViewByState() {
        switch (state) {
        case RELEASE_To_REFRESH:
            progressBar.setVisibility(View.VISIBLE);

            Log.v(TAG, "当前状态，松开刷新");
            break;
        case PULL_To_REFRESH:
            progressBar.setVisibility(View.VISIBLE);
            // 是由RELEASE_To_REFRESH状态转变来的
            if (isBack) {
                isBack = false;

            } else {
            }
            Log.v(TAG, "当前状态，下拉刷新");
            break;

        case REFRESHING:

            headView.setPadding(0, 0, 0, 0);

            progressBar.setVisibility(View.VISIBLE);

            Log.v(TAG, "当前状态,正在刷新...");
            break;
        case DONE:
            headView.setPadding(0, -1 * headContentHeight, 0, 0);

            progressBar.setVisibility(View.GONE);
            Log.v(TAG, "当前状态，done");
            break;
        }
    }

    public void setOnRefreshListenerHead(
            OnRefreshListenerHeader refreshListenerHeader) {
        this.refreshListenerHeader = refreshListenerHeader;
        isRefreshableHeader = true;
    }


    public interface OnRefreshListenerHeader {
        public void onRefresh();
    }

    public interface OnRefreshListenerFooter {
        public void onRefresh();
    }

    public void onRefreshCompleteHeader() {
        state = DONE;
        changeHeaderViewByState();
    }

    private void onRefresh() {
        if (refreshListenerHeader != null) {
            refreshListenerHeader.onRefresh();
        }
    }

    // 此方法直接照搬自网络上的一个下拉刷新的demo，此处是“估计”headView的width以及height
    private void measureView(View child) {
        ViewGroup.LayoutParams p = child.getLayoutParams();
        if (p == null) {
            p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT);
        }
        int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width);
        int lpHeight = p.height;
        int childHeightSpec;
        if (lpHeight > 0) {
            childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,
                    MeasureSpec.EXACTLY);
        } else {
            childHeightSpec = MeasureSpec.makeMeasureSpec(0,
                    MeasureSpec.UNSPECIFIED);
        }
        child.measure(childWidthSpec, childHeightSpec);
    }

    public void setAdapter(BaseAdapter adapter) {
        super.setAdapter(adapter);
    }
}

对应头部布局：

<?xml version="1.0" encoding="utf-8"?>

<!-- ListView的头部 -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <View
        android:id="@+id/line"
        android:layout_width="0.2dip"
        android:layout_height="match_parent"
        android:layout_gravity="center_horizontal"
        android:background="@color/gray" />

    <LinearLayout
        android:id="@+id/drop_down_head"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:gravity="center_horizontal"
        android:orientation="vertical" >

        <View
            android:layout_width="0.2dip"
            android:layout_height="20dip"
            android:layout_gravity="center_horizontal"
            android:background="@color/gray" />

        <ProgressBar
            android:id="@+id/loading"
            android:layout_width="20dip"
            android:layout_height="20dip"
            android:background="@drawable/circle_shape"
            android:indeterminateDrawable="@drawable/loading" />
    </LinearLayout>

</FrameLayout>