Android-ListView 下拉刷新

分享一個下拉刷新的解決辦法，效果圖：

Main.java：

package example.com.list;
import java.util.LinkedList;
import example.com.list.R;
import example.com.list.R.id;
import example.com.list.R.layout;
import example.com.list.MyListView.OnRefreshListener;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MainActivity extends Activity {

	private LinkedList data;
	private BaseAdapter adapter;

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		data = new LinkedList();
	    for(int i=0;i<6;i++){
	    	data.add(String.valueOf(i));
	    }

		final MyListView listView = (MyListView) findViewById(R.id.listView);
		adapter = new BaseAdapter() {
			public View getView(int position, View convertView, ViewGroup parent) {
				 convertView=LayoutInflater.from(getApplicationContext()).inflate(R.layout.item, null);
				TextView textView = (TextView) convertView.findViewById(R.id.textView_item);
				textView.setText(data.get(position));
				return convertView;
			}

			public long getItemId(int position) {
				return position;
			}

			public Object getItem(int position) {
				return data.get(position);
			}

			public int getCount() {
				return data.size();
			}
		};
		listView.setAdapter(adapter);

		listView.setonRefreshListener(new OnRefreshListener() {
			public void onRefresh() {
				new AsyncTask() {
					protected Void doInBackground(Void... params) {
						try {
							Thread.sleep(1000);
						} catch (Exception e) {
							e.printStackTrace();
						}
						return null;
					}
					@Override
					protected void onPostExecute(Void result) {
						adapter.notifyDataSetChanged();
						listView.onRefreshComplete();
					}
				};
			}
		});
	}
}

package example.com.list;

import java.text.SimpleDateFormat;
import java.util.Date;
import example.com.list.R;
import example.com.list.R.drawable;
import example.com.list.R.id;
import example.com.list.R.layout;
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.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MyListView extends ListView implements OnScrollListener {

	private static final String TAG = listview;
	private final static int RELEASE_To_REFRESH = 0; //釋放刷新 
	private final static int PULL_To_REFRESH = 1;//拉動刷新 
	private final static int REFRESHING = 2;//正在刷新 
	private final static int DONE = 3;
	private final static int LOADING = 4;
	// 實際的padding的距離與界面上偏移距離的比例 
	private final static int RATIO = 3;
	private LayoutInflater inflater;
	private LinearLayout headView;
	private TextView tipsTextview;
	private TextView lastUpdatedTextView;
	private ImageView arrowImageView;
	private ProgressBar progressBar;
	private RotateAnimation animation;
	private RotateAnimation reverseAnimation;
	 // 用於保證startY的值在一個完整的touch事件中只被記錄一次 
	private boolean isRecored;
	private int headContentWidth;
	private int headContentHeight;
	private int startY;
	private int firstItemIndex;
	private int state;
	private boolean isBack;
	private OnRefreshListener refreshListener;
	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);
		measureView(headView);
		headContentHeight = headView.getMeasuredHeight();
		headContentWidth = headView.getMeasuredWidth();
		headView.setPadding(0, -1 * headContentHeight, 0, 0);
		headView.invalidate();
		addHeaderView(headView, null, false);
		setOnScrollListener(this);
		animation = new RotateAnimation(0, -180,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f);
		animation.setInterpolator(new LinearInterpolator());
		animation.setDuration(250);
		animation.setFillAfter(true);
		reverseAnimation = new RotateAnimation(-180, 0,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f);
		reverseAnimation.setInterpolator(new LinearInterpolator());
		reverseAnimation.setDuration(200);
		reverseAnimation.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();
				}
				break;
			case MotionEvent.ACTION_UP:
				if (state != REFRESHING && state != LOADING) {
					if (state == DONE) {
					}
					if (state == PULL_To_REFRESH) {
						state = DONE;
						changeHeaderViewByState();
					}
					if (state == RELEASE_To_REFRESH) {
						state = REFRESHING;
						changeHeaderViewByState();
						onRefresh();
					}
				}
				isRecored = false;
				isBack = false;
				break;
			case MotionEvent.ACTION_MOVE:
				int tempY = (int) event.getY();

				if (!isRecored && firstItemIndex == 0) {
		
					isRecored = true;
					startY = tempY;
				}
				if (state != REFRESHING && isRecored && state != LOADING) {
					 // 保證在設置padding的過程中，當前的位置一直是在head，否則如果當列表超出屏幕的話，當在上推的時候，列表會同時進行滾動
					// 可以松手去刷新了
					if (state == RELEASE_To_REFRESH) {
						setSelection(0);
						 // 往上推了，推到了屏幕足夠掩蓋head的程度，但是還沒有推到全部掩蓋的地步
						if (((tempY - startY) / RATIO < headContentHeight)
								&& (tempY - startY) > 0) {
							state = PULL_To_REFRESH;
							changeHeaderViewByState();
						}
						// 一下子推到頂了 
						else if (tempY - startY <= 0) {
							state = DONE;
							changeHeaderViewByState();
						}
						// 往下拉了，或者還沒有上推到屏幕頂部掩蓋head的地步
						else {
							// 不用進行特別的操作，只用更新paddingTop的值就行了
						}
					}
					// 還沒有到達顯示松開刷新的時候,DONE或者是PULL_To_REFRESH狀態 
					if (state == PULL_To_REFRESH) {
						setSelection(0);
						// 下拉到可以進入RELEASE_TO_REFRESH的狀態
						if ((tempY - startY) / RATIO >= headContentHeight) {
							state = RELEASE_To_REFRESH;
							isBack = true;
							changeHeaderViewByState();
						}
						// 上推到頂了
						else if (tempY - startY <= 0) {
							state = DONE;
							changeHeaderViewByState();
						}
					}
					// done狀態下 
					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);
	}
	// 當狀態改變時候，調用該方法，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(animation);
			tipsTextview.setText(Release);
			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狀態轉變來的
			if (isBack) {
				isBack = false;
				arrowImageView.clearAnimation();
				arrowImageView.startAnimation(reverseAnimation);
				tipsTextview.setText(Pull down);
			} else {
				tipsTextview.setText(Pull down);
			}
			break;
		case REFRESHING:
			headView.setPadding(0, 0, 0, 0);
			progressBar.setVisibility(View.VISIBLE);
			arrowImageView.clearAnimation();
			arrowImageView.setVisibility(View.GONE);
			tipsTextview.setText(Refreshing...);
			lastUpdatedTextView.setVisibility(View.VISIBLE);
			break;
		case DONE:
			headView.setPadding(0, -1 * headContentHeight, 0, 0);
			progressBar.setVisibility(View.GONE);
			arrowImageView.clearAnimation();
			arrowImageView.setImageResource(R.drawable.arrow_down);
			tipsTextview.setText(Pull down);
			lastUpdatedTextView.setVisibility(View.VISIBLE);
			break;
		}
	}
	public void setonRefreshListener(OnRefreshListener refreshListener) {
		this.refreshListener = refreshListener;
		isRefreshable = true;
	}
	public interface OnRefreshListener {
		public void onRefresh();
	}
	public void onRefreshComplete() {
		state = DONE;
		SimpleDateFormat format=new SimpleDateFormat(yyyy.MM.dd. HH:mm);
		String date=format.format(new Date());
		lastUpdatedTextView.setText(recently: + date);
		changeHeaderViewByState();
	}
	private void onRefresh() {
		if (refreshListener != null) {
			refreshListener.onRefresh();
		}
	}
	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.MM.dd. HH:mm);
		String date=format.format(new Date());
		lastUpdatedTextView.setText(recently: + date);
		super.setAdapter(adapter);
	}
}