ListView 下拉 刷新

package com.jjmmbb.db.ex;

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.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.jjmmbb.dolist.R;

/**
 * 下拉时显示headview的list<br/>
 * 下拉时修改上边距,使headview逐渐显示;<br/>
 * 上推时修改上边距,使headview逐渐隐藏;<br/>
 * 松开时修改上边距,使headview完全隐藏;<br/>
 * 
 * @author yizhe
 * @date 2012-10-25
 */
public class MyListView extends ListView implements OnScrollListener {

	private static final String TAG = "listview";

	private final static int RELEASE_To_REFRESH = 0;// 松开刷新 状态
	private final static int PULL_To_REFRESH = 1;// 下拉刷新 状态
	private final static int REFRESHING = 2; // 刷新中 状态
	private final static int DONE = 3; // 取消操作 状态
	private final static int LOADING = 4;

	private boolean isBack;// 是否发生 "松开刷新" 到 "下拉刷新" 的状态转变

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

	private LayoutInflater inflater;

	private LinearLayout headView; // listview的头

	private TextView tipsTextview;// 提示文本
	// private TextView lastUpdatedTextView; //最后更新时间的文本
	private ImageView arrowImageView; // 箭头
	private ProgressBar progressBar; // 进度条,刷新的时候用,dolist没有使用到

	private RotateAnimation animation2up; // 箭头由下转到上的动画
	private RotateAnimation animation2dowm; // 箭头由上转下的动画

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

	// private int headContentWidth;
	private int headContentHeight;// headview的实际内容高度

	private int startY;
	private int firstItemIndex;

	private int state;// 状态

	private OnRefreshListener refreshListener;// 刷新接口

	private boolean isRefreshable;

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

	public MyListView(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);

		headView = (LinearLayout) inflater.inflate(R.layout.head, null);

		arrowImageView = (ImageView) headView
				.findViewById(R.id.head_arrowImageView);
		arrowImageView.setMinimumWidth(70);
		arrowImageView.setMinimumHeight(50);
		progressBar = (ProgressBar) headView
				.findViewById(R.id.head_progressBar);
		tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView);
		// lastUpdatedTextView = (TextView) headView
		// .findViewById(R.id.head_lastUpdatedTextView);
		// lastUpdatedTextView.setVisibility(View.GONE);

		measureView(headView);
		headContentHeight = headView.getMeasuredHeight();
		// headContentWidth = headView.getMeasuredWidth();

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

		addHeaderView(headView, null, false);// 添加头
		setOnScrollListener(this);

		animation2up = new RotateAnimation(0, -180,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f);
		animation2up.setInterpolator(new LinearInterpolator());
		animation2up.setDuration(250);
		animation2up.setFillAfter(true);

		animation2dowm = new RotateAnimation(-180, 0,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f);
		animation2dowm.setInterpolator(new LinearInterpolator());
		animation2dowm.setDuration(200);
		animation2dowm.setFillAfter(true);

		state = DONE;
		isRefreshable = false;
	}

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

	public void onScrollStateChanged(AbsListView arg0, int arg1) {
	}

	public boolean onTouchEvent(MotionEvent event) {

		if (isRefreshable) {
			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();
						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);
						// 下拉距离<headview的实际高度,进入 下拉刷新 状态
						if (((tempY - startY) / RATIO < headContentHeight)
								&& (tempY - startY) > 0) {
							state = PULL_To_REFRESH;// 进入 下拉刷新 状态
							isBack = true;
							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);
						// 下拉距离>headview的实际高度,进入 松开刷新 状态
						if ((tempY - startY) / RATIO >= headContentHeight) {
							state = RELEASE_To_REFRESH; // 进入 松开刷新 状态
							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paddingTop;达到向上推的效果
					if (state == PULL_To_REFRESH) {
						headView.setPadding(0, (tempY - startY) / RATIO
								- headContentHeight, 0, 0);
					}

					// 更新headView的paddingTop;达到向下拉的效果
					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:
			arrowImageView.setVisibility(View.VISIBLE);
			progressBar.setVisibility(View.GONE);
			tipsTextview.setVisibility(View.VISIBLE);
			// lastUpdatedTextView.setVisibility(View.VISIBLE);

			arrowImageView.clearAnimation();
			arrowImageView.startAnimation(animation2up);

			tipsTextview.setText("松开新增");

			Log.v(TAG, "当前状态，松开刷新");
			break;
		case PULL_To_REFRESH:
			progressBar.setVisibility(View.GONE);
			tipsTextview.setVisibility(View.VISIBLE);
			// lastUpdatedTextView.setVisibility(View.VISIBLE);
			arrowImageView.clearAnimation();
			// arrowImageView.setVisibility(View.VISIBLE);
			// 是由RELEASE_To_REFRESH状态转变来的
			if (isBack) {
				isBack = false;
				arrowImageView.startAnimation(animation2dowm);
			}
			tipsTextview.setText("下拉新增");
			Log.v(TAG, "当前状态，下拉新增");
			break;

		case REFRESHING:
			headView.setPadding(0, 0, 0, 0); // headview归位,显示刷新中视图
			// progressBar.setVisibility(View.VISIBLE); // 显示刷新中进度,dolist没有使用到
			// arrowImageView.clearAnimation();
			// arrowImageView.setVisibility(View.GONE); // 隐藏箭头
			// tipsTextview.setText("正在刷新...");
			// lastUpdatedTextView.setVisibility(View.VISIBLE);

			Log.v(TAG, "当前状态,正在刷新...");
			break;
		case DONE:
			// 通过设置上边距,使headview隐藏(下拉时修改上边距,使逐渐显示headview;)
			headView.setPadding(0, -1 * headContentHeight, 0, 0);// 逐渐修改上边距可以实现回收动画
			progressBar.setVisibility(View.GONE);
			arrowImageView.clearAnimation();
			// arrowImageView.setImageResource(R.drawable.arrow_down);
			// tipsTextview.setText("下拉新增");
			// lastUpdatedTextView.setVisibility(View.VISIBLE);

			Log.v(TAG, "当前状态，done");
			break;
		}
	}

	// 设置刷新接口
	public void setonRefreshListener(OnRefreshListener refreshListener) {
		this.refreshListener = refreshListener;
		isRefreshable = true;
	}

	// 刷新完成时,手动调用这个类
	public void onRefreshComplete() {
		// SimpleDateFormat format = new SimpleDateFormat("yyyy年MM月dd日  HH:mm");
		// String date = format.format(new Date());
		// lastUpdatedTextView.setText("最近更新:" + date);
		state = DONE;
		changeHeaderViewByState();
	}

	// 进入刷新状态时,将调用接口的刷新方法
	private void onRefresh() {
		if (refreshListener != null) {
			refreshListener.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.FILL_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) {
		// SimpleDateFormat format = new SimpleDateFormat("yyyy年MM月dd日  HH:mm");
		// String date = format.format(new Date());
		// lastUpdatedTextView.setText("最近更新:" + date);
		super.setAdapter(adapter);
	}

	// 刷新接口,实现本接口来完成刷新
	public interface OnRefreshListener {
		public void onRefresh();
	}
}

head.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- ListView的头部 -->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="#ffffff" >

    <!-- 内容 -->

    <RelativeLayout
        android:id="@+id/head_contentLayout"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="30dp" >

        <!-- 箭头图像、进度条 -->

        <FrameLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true" >

            <!-- 箭头 -->

            <ImageView
                android:id="@+id/head_arrowImageView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:src="@drawable/arrow_down" />

            <!-- 进度条 -->

            <ProgressBar
                android:id="@+id/head_progressBar"
                style="?android:attr/progressBarStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:visibility="gone" />
        </FrameLayout>

        <!-- 提示、最近更新 -->

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:gravity="center_horizontal"
            android:orientation="vertical" >

            <!-- 提示 -->

            <TextView
                android:id="@+id/head_tipsTextView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="下拉刷新"
                android:textSize="15dp" />

            <!-- 最近更新 -->

            <TextView
                android:id="@+id/head_lastUpdatedTextView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="上次更新"
                android:textSize="12dp" />
        </LinearLayout>
    </RelativeLayout>

</LinearLayout>

调用示例

	listView.setAdapter(adapter);

		listView.setonRefreshListener(new OnRefreshListener() {
			public void onRefresh() {
				// 这里执行刷新
				
				// 刷新完了调用
				adapter.notifyDataSetChanged();
				listView.onRefreshComplete();
			}
		});