ListView下拉刷新、上拉載入更多之封裝改進

在Android中ListView下拉刷新、上拉載入更多示例一文中，Maxwin兄給出的控件比較強大，前面有詳細介紹，但是有個不足就是，裡面使用了一些資源文件，包括圖片，String，layout，這樣不利於封裝打包，下面我將源碼進行改進，所有布局全部用代碼實現，這樣直接將src和assets打包成jar就成了一個非常方便以後使用的擴展ListView控件，代碼如下：

XListView：

/**
 * @file XListView.java
 * @package me.maxwin.view
 * @create Mar 18, 2012 6:28:41 PM
 * @author Maxwin
 * @description An ListView support (a) Pull down to refresh, (b) Pull up to load more.
 * 		Implement IXListViewListener, and see stopRefresh() / stopLoadMore().
 */
package com.home.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.animation.DecelerateInterpolator;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.Scroller;
import android.widget.TextView;

public class XListView extends ListView implements OnScrollListener {

	private float mLastY = -1; // save event y
	private Scroller mScroller; // used for scroll back
	private OnScrollListener mScrollListener; // user's scroll listener

	// the interface to trigger refresh and load more.
	private IXListViewListener mListViewListener;

	// -- header view
	private XListViewHeader mHeaderView;
	// header view content, use it to calculate the Header's height. And hide it
	// when disable pull refresh.
	private RelativeLayout mHeaderViewContent;
	private TextView mHeaderTimeView;
	private int mHeaderViewHeight; // header view's height
	private boolean mEnablePullRefresh = true;
	private boolean mPullRefreshing = false; // is refreashing.

	// -- footer view
	private XListViewFooter mFooterView;
	private boolean mEnablePullLoad;
	private boolean mPullLoading;
	private boolean mIsFooterReady = false;

	// total list items, used to detect is at the bottom of listview.
	private int mTotalItemCount;

	// for mScroller, scroll back from header or footer.
	private int mScrollBack;
	private final static int SCROLLBACK_HEADER = 0;
	private final static int SCROLLBACK_FOOTER = 1;

	private final static int SCROLL_DURATION = 400; // scroll back duration
	private final static int PULL_LOAD_MORE_DELTA = 50; // when pull up >= 50px
														// at bottom, trigger
														// load more.
	private final static float OFFSET_RADIO = 1.8f; // support iOS like pull
													// feature.

	/**
	 * @param context
	 */
	public XListView(Context context) {
		super(context);
		initWithContext(context);
	}

	public XListView(Context context, AttributeSet attrs) {
		super(context, attrs);
		initWithContext(context);
	}

	public XListView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		initWithContext(context);
	}

	private void initWithContext(Context context) {
		mScroller = new Scroller(context, new DecelerateInterpolator());
		// XListView need the scroll event, and it will dispatch the event to
		// user's listener (as a proxy).
		super.setOnScrollListener(this);

		// init header view
		mHeaderView = new XListViewHeader(context);
		mHeaderViewContent = (RelativeLayout) mHeaderView
				.findViewById(XListViewHeader.RELAYOUT_ID);
		mHeaderTimeView = (TextView) mHeaderView
				.findViewById(XListViewHeader.HEAD_TIME_VIEW_ID);
		addHeaderView(mHeaderView);

		// init footer view
		mFooterView = new XListViewFooter(context);

		// init header height
		mHeaderView.getViewTreeObserver().addOnGlobalLayoutListener(
				new OnGlobalLayoutListener() {
					@Override
					public void onGlobalLayout() {
						mHeaderViewHeight = mHeaderViewContent.getHeight();
						getViewTreeObserver()
								.removeGlobalOnLayoutListener(this);
					}
				});
	}

	@Override
	public void setAdapter(ListAdapter adapter) {
		// make sure XListViewFooter is the last footer view, and only add once.
		if (mIsFooterReady == false) {
			mIsFooterReady = true;
			addFooterView(mFooterView);
		}
		super.setAdapter(adapter);
	}

	/**
	 * enable or disable pull down refresh feature.
	 * 
	 * @param enable
	 */
	public void setPullRefreshEnable(boolean enable) {
		mEnablePullRefresh = enable;
		if (!mEnablePullRefresh) { // disable, hide the content
			mHeaderViewContent.setVisibility(View.INVISIBLE);
		} else {
			mHeaderViewContent.setVisibility(View.VISIBLE);
		}
	}

	/**
	 * enable or disable pull up load more feature.
	 * 
	 * @param enable
	 */
	public void setPullLoadEnable(boolean enable) {
		mEnablePullLoad = enable;
		if (!mEnablePullLoad) {
			mFooterView.hide();
			mFooterView.setOnClickListener(null);
		} else {
			mPullLoading = false;
			mFooterView.show();
			mFooterView.setState(XListViewFooter.STATE_NORMAL);
			// both "pull up" and "click" will invoke load more.
			mFooterView.setOnClickListener(new OnClickListener() {
				@Override
				public void onClick(View v) {
					startLoadMore();
				}
			});
		}
	}

	/**
	 * stop refresh, reset header view.
	 */
	public void stopRefresh() {
		if (mPullRefreshing == true) {
			mPullRefreshing = false;
			resetHeaderHeight();
		}
	}

	/**
	 * stop load more, reset footer view.
	 */
	public void stopLoadMore() {
		if (mPullLoading == true) {
			mPullLoading = false;
			mFooterView.setState(XListViewFooter.STATE_NORMAL);
		}
	}

	/**
	 * set last refresh time
	 * 
	 * @param time
	 */
	public void setRefreshTime(String time) {
		mHeaderTimeView.setText(time);
	}

	private void invokeOnScrolling() {
		if (mScrollListener instanceof OnXScrollListener) {
			OnXScrollListener l = (OnXScrollListener) mScrollListener;
			l.onXScrolling(this);
		}
	}

	private void updateHeaderHeight(float delta) {
		mHeaderView.setVisiableHeight((int) delta
				+ mHeaderView.getVisiableHeight());
		if (mEnablePullRefresh && !mPullRefreshing) { // 未處於刷新狀態，更新箭頭
			if (mHeaderView.getVisiableHeight() > mHeaderViewHeight) {
				mHeaderView.setState(XListViewHeader.STATE_READY);
			} else {
				mHeaderView.setState(XListViewHeader.STATE_NORMAL);
			}
		}
		setSelection(0); // scroll to top each time
	}

	/**
	 * reset header view's height.
	 */
	private void resetHeaderHeight() {
		int height = mHeaderView.getVisiableHeight();
		if (height == 0) // not visible.
			return;
		// refreshing and header isn't shown fully. do nothing.
		if (mPullRefreshing && height <= mHeaderViewHeight) {
			return;
		}
		int finalHeight = 0; // default: scroll back to dismiss header.
		// is refreshing, just scroll back to show all the header.
		if (mPullRefreshing && height > mHeaderViewHeight) {
			finalHeight = mHeaderViewHeight;
		}
		mScrollBack = SCROLLBACK_HEADER;
		mScroller.startScroll(0, height, 0, finalHeight - height,
				SCROLL_DURATION);
		// trigger computeScroll
		invalidate();
	}

	private void updateFooterHeight(float delta) {
		int height = mFooterView.getBottomMargin() + (int) delta;
		if (mEnablePullLoad && !mPullLoading) {
			if (height > PULL_LOAD_MORE_DELTA) { // height enough to invoke load
													// more.
				mFooterView.setState(XListViewFooter.STATE_READY);
			} else {
				mFooterView.setState(XListViewFooter.STATE_NORMAL);
			}
		}
		mFooterView.setBottomMargin(height);

		// setSelection(mTotalItemCount - 1); // scroll to bottom
	}

	private void resetFooterHeight() {
		int bottomMargin = mFooterView.getBottomMargin();
		if (bottomMargin > 0) {
			mScrollBack = SCROLLBACK_FOOTER;
			mScroller.startScroll(0, bottomMargin, 0, -bottomMargin,
					SCROLL_DURATION);
			invalidate();
		}
	}

	private void startLoadMore() {
		mPullLoading = true;
		mFooterView.setState(XListViewFooter.STATE_LOADING);
		if (mListViewListener != null) {
			mListViewListener.onLoadMore();
		}
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		if (mLastY == -1) {
			mLastY = ev.getRawY();
		}

		switch (ev.getAction()) {
		case MotionEvent.ACTION_DOWN:
			mLastY = ev.getRawY();
			break;
		case MotionEvent.ACTION_MOVE:
			final float deltaY = ev.getRawY() - mLastY;
			mLastY = ev.getRawY();
			System.out.println("數據監測：" + getFirstVisiblePosition() + "---->"
					+ getLastVisiblePosition());
			if (getFirstVisiblePosition() == 0
					&& (mHeaderView.getVisiableHeight() > 0 || deltaY > 0)) {
				// the first item is showing, header has shown or pull down.
				updateHeaderHeight(deltaY / OFFSET_RADIO);
				invokeOnScrolling();
			} else if (getLastVisiblePosition() == mTotalItemCount - 1
					&& (mFooterView.getBottomMargin() > 0 || deltaY < 0)) {
				// last item, already pulled up or want to pull up.
				updateFooterHeight(-deltaY / OFFSET_RADIO);
			}
			break;
		default:
			mLastY = -1; // reset
			if (getFirstVisiblePosition() == 0) {
				// invoke refresh
				if (mEnablePullRefresh
						&& mHeaderView.getVisiableHeight() > mHeaderViewHeight) {
					mPullRefreshing = true;
					mHeaderView.setState(XListViewHeader.STATE_REFRESHING);
					if (mListViewListener != null) {
						mListViewListener.onRefresh();
					}
				}
				resetHeaderHeight();
			}
			if (getLastVisiblePosition() == mTotalItemCount - 1) {
				// invoke load more.
				if (mEnablePullLoad
						&& mFooterView.getBottomMargin() > PULL_LOAD_MORE_DELTA) {
					startLoadMore();
				}
				resetFooterHeight();
			}
			break;
		}
		return super.onTouchEvent(ev);
	}

	@Override
	public void computeScroll() {
		if (mScroller.computeScrollOffset()) {
			if (mScrollBack == SCROLLBACK_HEADER) {
				mHeaderView.setVisiableHeight(mScroller.getCurrY());
			} else {
				mFooterView.setBottomMargin(mScroller.getCurrY());
			}
			postInvalidate();
			invokeOnScrolling();
		}
		super.computeScroll();
	}

	@Override
	public void setOnScrollListener(OnScrollListener l) {
		mScrollListener = l;
	}

	@Override
	public void onScrollStateChanged(AbsListView view, int scrollState) {
		if (mScrollListener != null) {
			mScrollListener.onScrollStateChanged(view, scrollState);
		}
	}

	@Override
	public void onScroll(AbsListView view, int firstVisibleItem,
			int visibleItemCount, int totalItemCount) {
		// send to user's listener
		mTotalItemCount = totalItemCount;
		if (mScrollListener != null) {
			mScrollListener.onScroll(view, firstVisibleItem, visibleItemCount,
					totalItemCount);
		}
	}

	public void setXListViewListener(IXListViewListener l) {
		mListViewListener = l;
	}

	/**
	 * you can listen ListView.OnScrollListener or this one. it will invoke
	 * onXScrolling when header/footer scroll back.
	 */
	public interface OnXScrollListener extends OnScrollListener {
		public void onXScrolling(View view);
	}

	/**
	 * implements this interface to get refresh/load more event.
	 */
	public interface IXListViewListener {
		public void onRefresh();

		public void onLoadMore();
	}
}

XListViewFooter：

package com.home.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class XListViewFooter extends LinearLayout {
	public final static int STATE_NORMAL = 0;
	public final static int STATE_READY = 1;
	public final static int STATE_LOADING = 2;

	private Context mContext;

	private RelativeLayout mContentView;
	private ProgressBar mProgressBar;
	private TextView mHintView;

	public XListViewFooter(Context context) {
		super(context);
		initView(context);
	}

	public XListViewFooter(Context context, AttributeSet attrs) {
		super(context, attrs);
		initView(context);
	}

	public void setState(int state) {
		mHintView.setVisibility(View.INVISIBLE);
		mProgressBar.setVisibility(View.INVISIBLE);
		mHintView.setVisibility(View.INVISIBLE);
		if (state == STATE_READY) {
			mHintView.setVisibility(View.VISIBLE);
			mHintView.setText("松開載入更多");
		} else if (state == STATE_LOADING) {
			mProgressBar.setVisibility(View.VISIBLE);
		} else {
			mHintView.setVisibility(View.VISIBLE);
			mHintView.setText("查看更多");
		}
	}

	public void setBottomMargin(int height) {
		if (height < 0)
			return;
		LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) mContentView
				.getLayoutParams();
		lp.bottomMargin = height;
		mContentView.setLayoutParams(lp);
	}

	public int getBottomMargin() {
		LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) mContentView
				.getLayoutParams();
		return lp.bottomMargin;
	}

	/**
	 * normal status
	 */
	public void normal() {
		mHintView.setVisibility(View.VISIBLE);
		mProgressBar.setVisibility(View.GONE);
	}

	/**
	 * loading status
	 */
	public void loading() {
		mHintView.setVisibility(View.GONE);
		mProgressBar.setVisibility(View.VISIBLE);
	}

	/**
	 * hide footer when disable pull load more
	 */
	public void hide() {
		LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) mContentView
				.getLayoutParams();
		lp.height = 0;
		mContentView.setLayoutParams(lp);
	}

	/**
	 * show footer
	 */
	public void show() {
		LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) mContentView
				.getLayoutParams();
		lp.height = LayoutParams.WRAP_CONTENT;
		mContentView.setLayoutParams(lp);
	}

	private void initView(Context context) {
		mContext = context;
		// 根布局
		LinearLayout moreView = new LinearLayout(mContext);
		moreView.setLayoutParams(new LinearLayout.LayoutParams(
				LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
		// 將根布局加到該LinearLayout中
		addView(moreView);

		// 根布局裡面的相對布局
		mContentView = new RelativeLayout(mContext);
		LinearLayout.LayoutParams linearLp1 = new LinearLayout.LayoutParams(
				LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
		mContentView.setPadding(10, 10, 10, 10);
		// 將相對布局relayout加到moreView根布局中
		moreView.addView(mContentView, linearLp1);

		// 進度條mProgressBar
		mProgressBar = new ProgressBar(mContext);
		RelativeLayout.LayoutParams relativeLp1 = new RelativeLayout.LayoutParams(
				LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
		relativeLp1.addRule(RelativeLayout.CENTER_IN_PARENT);
		mProgressBar.setVisibility(View.INVISIBLE);
		// 將mProgressBar加入相對布局relayout中
		mContentView.addView(mProgressBar, relativeLp1);

		// 查看更多的TextView
		mHintView = new TextView(mContext);
		mHintView.setText("查看更多");
		mHintView.setGravity(Gravity.CENTER);
		RelativeLayout.LayoutParams relativeLp2 = new RelativeLayout.LayoutParams(
				LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
		relativeLp2.addRule(RelativeLayout.CENTER_IN_PARENT);
		// 將其加入相對布局relayout中
		mContentView.addView(mHintView, relativeLp2);
	}

}

XListViewHeader：

package com.home.view;

import java.io.IOException;
import java.io.InputStream;

import android.content.Context;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class XListViewHeader extends LinearLayout {
	private LinearLayout mContainer;
	private ImageView mArrowImageView;
	private ProgressBar mProgressBar;
	private TextView mHintTextView;
	private int mState = STATE_NORMAL;

	private Animation mRotateUpAnim;
	private Animation mRotateDownAnim;

	private final int ROTATE_ANIM_DURATION = 180;

	public final static int STATE_NORMAL = 0;
	public final static int STATE_READY = 1;
	public final static int STATE_REFRESHING = 2;
	public static final int LINEAROUT_1_ID = 1;
	public static final int RELAYOUT_ID = 2;
	public static final int HEAD_TIME_VIEW_ID = 3;

	public XListViewHeader(Context context) {
		super(context);
		initView(context);
	}

	/**
	 * @param context
	 * @param attrs
	 */
	public XListViewHeader(Context context, AttributeSet attrs) {
		super(context, attrs);
		initView(context);
	}

	private void initView(Context context) {
		// 根布局
		mContainer = new LinearLayout(context);
		mContainer.setGravity(Gravity.BOTTOM);
		// 初始情況，設置下拉刷新view高度為0
		LinearLayout.LayoutParams linearLp1 = new LinearLayout.LayoutParams(
				LayoutParams.MATCH_PARENT, 0);
		// 將根布局加入該LinearLayout中
		addView(mContainer, linearLp1);
		setGravity(Gravity.BOTTOM);

		// 裡面的相對布局
		RelativeLayout relayout = new RelativeLayout(context);
		relayout.setId(RELAYOUT_ID);
		LinearLayout.LayoutParams linearLp2 = new LinearLayout.LayoutParams(
				LayoutParams.MATCH_PARENT, 60);
		// 將裡面的相對布局加入根布局中
		mContainer.addView(relayout, linearLp2);

		// 相對布局裡的子線性布局1
		LinearLayout linear1 = new LinearLayout(context);
		linear1.setId(LINEAROUT_1_ID);
		RelativeLayout.LayoutParams relativeLp1 = new RelativeLayout.LayoutParams(
				LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
		relativeLp1.addRule(RelativeLayout.CENTER_IN_PARENT);
		linear1.setGravity(Gravity.CENTER);
		linear1.setOrientation(LinearLayout.VERTICAL);
		// 將子布局linear1加入relayout中
		relayout.addView(linear1, relativeLp1);

		// 下拉刷新提示TextView
		mHintTextView = new TextView(context);
		mHintTextView.setText("下拉刷新");
		LinearLayout.LayoutParams linearLp3 = new LinearLayout.LayoutParams(
				LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
		// 將TextView加入linear1中
		linear1.addView(mHintTextView, linearLp3);

		// 子線性布局1（linear1）裡的線性布局linear12
		LinearLayout linear12 = new LinearLayout(context);
		LinearLayout.LayoutParams linearLp4 = new LinearLayout.LayoutParams(
				LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
		linearLp4.setMargins(0, 3, 0, 0);
		// 將linear12加入linear1中
		linear1.addView(linear12, linearLp4);

		// 提示時間TextView
		TextView tv = new TextView(context);
		tv.setText("上次更新時間：");
		tv.setTextSize(12);
		// 將提示時間TextView加入linear12
		linear12.addView(tv, linearLp3);

		// 時間值TextView
		TextView tv2 = new TextView(context);
		tv2.setId(HEAD_TIME_VIEW_ID);
		tv2.setTextSize(12);
		// 將時間值TextView加入linear12
		linear12.addView(tv2, linearLp3);

		// ImageView
		mArrowImageView = new ImageView(context);
		RelativeLayout.LayoutParams relativeLp2 = new RelativeLayout.LayoutParams(
				ViewGroup.LayoutParams.WRAP_CONTENT,
				ViewGroup.LayoutParams.WRAP_CONTENT);
		relativeLp2.rightMargin = 20;
		relativeLp2.addRule(RelativeLayout.CENTER_VERTICAL);
		relativeLp2.addRule(RelativeLayout.LEFT_OF, LINEAROUT_1_ID);
		mArrowImageView.setImageBitmap(readAssetImage(context));
		// 將ImageView加到相對布局relayout中
		relayout.addView(mArrowImageView, relativeLp2);

		// ProgressBar
		mProgressBar = new ProgressBar(context);
		RelativeLayout.LayoutParams relativeLp3 = new RelativeLayout.LayoutParams(
				45, 45);
		relativeLp3.addRule(RelativeLayout.LEFT_OF, LINEAROUT_1_ID);
		relativeLp3.addRule(RelativeLayout.CENTER_VERTICAL);
		relativeLp3.rightMargin = 20;
		mProgressBar.setVisibility(View.INVISIBLE);
		// 將mProgressBar加到相對布局relayout中
		relayout.addView(mProgressBar, relativeLp3);

		mRotateUpAnim = new RotateAnimation(0.0f, -180.0f,
				Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
				0.5f);
		mRotateUpAnim.setDuration(ROTATE_ANIM_DURATION);
		mRotateUpAnim.setFillAfter(true);
		mRotateDownAnim = new RotateAnimation(-180.0f, 0.0f,
				Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
				0.5f);
		mRotateDownAnim.setDuration(ROTATE_ANIM_DURATION);
		mRotateDownAnim.setFillAfter(true);
	}

	public void setState(int state) {
		if (state == mState)
			return;
		if (state == STATE_REFRESHING) { // 顯示進度
			mArrowImageView.clearAnimation();
			mArrowImageView.setVisibility(View.INVISIBLE);
			mProgressBar.setVisibility(View.VISIBLE);
		} else { // 顯示箭頭圖片
			mArrowImageView.setVisibility(View.VISIBLE);
			mProgressBar.setVisibility(View.INVISIBLE);
		}
		switch (state) {
		case STATE_NORMAL:
			if (mState == STATE_READY) {
				mArrowImageView.startAnimation(mRotateDownAnim);
			}
			if (mState == STATE_REFRESHING) {
				mArrowImageView.clearAnimation();
			}
			mHintTextView.setText("下拉刷新");
			break;
		case STATE_READY:
			if (mState != STATE_READY) {
				mArrowImageView.clearAnimation();
				mArrowImageView.startAnimation(mRotateUpAnim);
				mHintTextView.setText("松開刷新數據");
			}
			break;
		case STATE_REFRESHING:
			mHintTextView.setText("正在加載...");
			break;
		default:
		}
		mState = state;
	}

	public void setVisiableHeight(int height) {
		if (height < 0)
			height = 0;
		LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) mContainer
				.getLayoutParams();
		lp.height = height;
		mContainer.setLayoutParams(lp);
	}

	public int getVisiableHeight() {
		return mContainer.getHeight();
	}

	/**
	 * 讀取assets裡面文件名為xlistview_arrow.png的圖片
	 * 
	 * @param context
	 * @return bitmap
	 */
	private Bitmap readAssetImage(Context context) {
		AssetManager asset = context.getAssets();
		InputStream assetFile = null;
		Bitmap bitmap = null;
		try {
			assetFile = asset.open("xlistview_arrow.png");
			bitmap = BitmapFactory.decodeStream(assetFile);
		} catch (IOException e) {
			e.printStackTrace();
		}
		return bitmap;
	}

}

然後將使用到的那張圖片放在assets目錄下和src一起打包即可。