Android—自定義控件實現ListView下拉刷新

這篇博客為大家介紹一個android常見的功能——ListView下拉刷新（參考自他人博客，網址忘記了，閱讀他的代碼自己理解注釋的，希望能幫助到大家）：

首先下拉未松手時候手機顯示這樣的界面：

下面的代碼是自定的扎樣的控件：

package com.dhsr.smartID.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
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.TextView;

import com.example.sirelinkscanapp.R;

/**
 * 自定義控件，完成下拉時候ListView顯示“圖標及提示正在刷新……”的布局
 * 
 * @author cyf
 * 
 */
public class XListViewHeader extends LinearLayout {
	private LinearLayout mContainer;
	// 圖片
	private ImageView mArrowImageView;
	// 圓形進度條
	private ProgressBar mProgressBar;
	private TextView mHintTextView;
	// 狀態
	private int mState = STATE_NORMAL;
	// 動畫
	private Animation mRotateUpAnim;
	private Animation mRotateDownAnim;
	private final int ROTATE_ANIM_DURATION = 180;
	// 正常
	public final static int STATE_NORMAL = 0;
	// 准備刷新
	public final static int STATE_READY = 1;
	// 刷新中
	public final static int STATE_REFRESHING = 2;

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

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

	/**
	 * “ 松開即可刷新……正在刷新……”的布局
	 * 
	 * @param context
	 */
	private void initView(Context context) {
		// 初始情況，設置下拉刷新view高度為0
		LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
				LayoutParams.MATCH_PARENT, 0);
		mContainer = (LinearLayout) LayoutInflater.from(context).inflate(
				R.layout.xlistview_header, null);
		// 加載視圖
		addView(mContainer, lp);
		// 居中方式
		setGravity(Gravity.BOTTOM);
		// 初始化控件
		mArrowImageView = (ImageView) findViewById(R.id.xlistview_header_arrow);
		mHintTextView = (TextView) findViewById(R.id.xlistview_header_hint_textview);
		mProgressBar = (ProgressBar) findViewById(R.id.xlistview_header_progressbar);
		// 設置動畫
		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);
	}

	/**
	 * 根據下拉狀態執行相應的功能，開始以及停止相應的動畫
	 * 
	 * @param state
	 */
	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) {
				// 開始動畫
				mArrowImageView.startAnimation(mRotateDownAnim);
			}
			//刷新中
			if (mState == STATE_REFRESHING) {
				// 清除動畫
				mArrowImageView.clearAnimation();
			}
			mHintTextView.setText(R.string.xlistview_header_hint_normal);
			break;
		case STATE_READY:
			if (mState != STATE_READY) {
				mArrowImageView.clearAnimation();
				mArrowImageView.startAnimation(mRotateUpAnim);
				mHintTextView.setText(R.string.xlistview_header_hint_ready);
			}
			break;
		case STATE_REFRESHING:
			mHintTextView.setText(R.string.xlistview_header_hint_loading);
			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();
	}

}

 接下來需要自定義自己的ListView繼承與android本身的ListView，方便自己添加新的方法。

package com.dhsr.smartID.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;

import com.example.sirelinkscanapp.R;

/**
 * 自定義ListView
 * 
 * @author cyf
 * 
 */
public class XListView extends ListView implements OnScrollListener {

	private final String TAG = "XListView";
	private float mLastY = -1;
	private Scroller mScroller;
	// 滑動
	private OnScrollListener mScrollListener;

	// 為外界創建監聽
	private IXListViewListener mListViewListener;

	// 剛才定義的自定義控件
	private XListViewHeader mHeaderView;

	private RelativeLayout mHeaderViewContent;
	private TextView mHeaderTimeView;
	private int mHeaderViewHeight; // header view's height
	private boolean mEnablePullRefresh = true;
	private boolean mPullRefreshing = false; // is refreashing.

	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);
	}

	/**
	 * 初始化控件
	 * 
	 * @param context
	 */
	private void initWithContext(Context context) {
		mScroller = new Scroller(context, new DecelerateInterpolator());

		super.setOnScrollListener(this);

		mHeaderView = new XListViewHeader(context);
		mHeaderViewContent = (RelativeLayout) mHeaderView
				.findViewById(R.id.xlistview_header_content);
		mHeaderTimeView = (TextView) mHeaderView
				.findViewById(R.id.xlistview_header_time);

		addHeaderView(mHeaderView, null, false);

		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) {
			if (mEnablePullLoad) {
				mIsFooterReady = true;
				// addFooterView(mFooterView);

			}
		}
		super.setAdapter(adapter);
	}

	public void setPullRefreshEnable(boolean enable) {
		mEnablePullRefresh = enable;
		if (!mEnablePullRefresh) { // disable, hide the content
			mHeaderViewContent.setVisibility(View.INVISIBLE);
		} else {
			mHeaderViewContent.setVisibility(View.VISIBLE);
		}
	}

	/**
	 * 停止刷新
	 */
	public void stopRefresh() {
		if (mPullRefreshing == true) {
			mPullRefreshing = false;
			resetHeaderHeight();
		}
	}

	// 可使進入Activity時便執行下拉刷新
	public void startRefresh() {
		if (mPullRefreshing == false) {
			mPullRefreshing = true;
			mHeaderView.setState(XListViewHeader.STATE_REFRESHING);
			mHeaderView.setVisiableHeight(90);
			if (mListViewListener != null) {
				mListViewListener.onRefresh();
			}
		}
	}

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

		}
	}

	/**
	 * 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);
			}
			if (mPullLoading) { // disable, hide the content
				mHeaderViewContent.setVisibility(View.INVISIBLE);
			} else {
				mHeaderViewContent.setVisibility(View.VISIBLE);
			}
		}
		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();
	}

	/**
	 * 觸屏監聽
	 */
	@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;
			// DLog.i(TAG, "deltaY is " + deltaY);
			mLastY = ev.getRawY();

			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) {
				// last item, already pulled up or want to pull up.

			}
			break;
		default:
			mLastY = -1; // reset
			if (getFirstVisiblePosition() == 0) {
				// invoke refresh
				if (!mPullRefreshing && mEnablePullRefresh && !mPullLoading
						&& mHeaderView.getVisiableHeight() > mHeaderViewHeight) {
					mPullRefreshing = true;
					mHeaderView.setState(XListViewHeader.STATE_REFRESHING);
					// DLog.i(TAG, "invoke refresh");
					if (mListViewListener != null) {
						// 此時執行刷刷新的方法
						mListViewListener.onRefresh();
					}
				}
				resetHeaderHeight();
			} else if (getLastVisiblePosition() == mTotalItemCount - 1) {
				// invoke load more.
				if (!mPullLoading && mEnablePullLoad && !mPullRefreshing) {
					// DLog.i(TAG, "invoke load more");

				}

			}
			break;
		}
		return super.onTouchEvent(ev);
	}

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

			}
			postInvalidate();
			invokeOnScrolling();
		}
		super.computeScroll();
	}

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

	/**
	 * 在滾動時回調，回調2-3次，手指沒拋開則回調2次，scrollState = 2的這次不回調 第1次：scrollState =
	 * SCROLL_STATE_TOUCH_SCROLL(1) 正在滾動 第2次：scrollState =
	 * SCROLL_STATE_FLING(2)手指做了拋的動作（手指離開屏幕前，用力滑了一下） 第3次：scrollState =
	 * SCROLL_STATE_IDLE(0) 停止滾動
	 */
	@Override
	public void onScrollStateChanged(AbsListView view, int scrollState) {
		if (mScrollListener != null) {
			mScrollListener.onScrollStateChanged(view, scrollState);
		}
		// 滑到底部時，自動加載更多。 也可以禁用此邏輯
		if (getLastVisiblePosition() == mTotalItemCount - 1
				&& scrollState == SCROLL_STATE_IDLE) {
			if (!mPullLoading && mEnablePullLoad && !mPullRefreshing) {
				// DLog.i(TAG, "invoke load more");

			}
		}
	}

	/**
	 * 正在滾動的時候回調，停止滾動時才停止回調，單擊時回調一次
	 */
	@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;
	}

	/**
	 * 監聽ListView的滑動事件
	 * 
	 * @author cyf
	 * 
	 */
	public interface OnXScrollListener extends OnScrollListener {
		public void onXScrolling(View view);
	}

	/**
	 * 自定義接口
	 */
	public interface IXListViewListener {
		// 下拉刷新時候執行的方法
		public void onRefresh();

		// 上拉加載時候執行的方法
		public void onLoadMore();
	}
}

 MainActivity的xml文件中的ListView就不要用android的ListView了，用上面自定義的ListView（加包名）

package com.test.andy;

import java.util.ArrayList;

import com.test.andy.view.XListView;
import com.test.andy.view.XListView.IXListViewListener;

import com.test.andy.R;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.ArrayAdapter;
/**
 * XListViewActivity
 * 實現IXListViewListener接口是為了實現其中的下拉刷新等方法
 * @author cyf
 *
 */
public class XListViewActivity extends Activity implements IXListViewListener {
	//自定義的ListView
	private XListView mListView;
	private ArrayAdapter<String> mAdapter;
	private ArrayList<String> items = new ArrayList<String>();
	private Handler mHandler;
	private int start = 0;
	private int refreshCnt = 0;
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		//初始化的時候加載20條數據
		geneItems();
		mListView = (XListView) findViewById(R.id.xListView);
		mListView.setPullLoadEnable(true);
		mAdapter = new ArrayAdapter<String>(this, R.layout.list_item, items);
		mListView.setAdapter(mAdapter);
//		mListView.setPullRefreshEnable(false);
		mListView.setXListViewListener(this);
		mHandler = new Handler();
		mListView.startRefresh();
	}

	private void geneItems() {
		for (int i = 0; i != 20; ++i) {
			items.add("refresh cnt " + (++start));
		}
	}

	private void onLoad() {
		mListView.stopRefresh();
		mListView.stopLoadMore();
		mListView.setRefreshTime("剛剛");
	}
	
	@Override
	public void onRefresh() {
		mHandler.postDelayed(new Runnable() {
			@Override
			public void run() {
				start = ++refreshCnt;
				items.clear();
				geneItems();
				// mAdapter.notifyDataSetChanged();
				mAdapter = new ArrayAdapter<String>(XListViewActivity.this, R.layout.list_item, items);
				mListView.setAdapter(mAdapter);
				onLoad();
			}
		}, 2000);
	}

	@Override
	public void onLoadMore() {
		mHandler.postDelayed(new Runnable() {
			@Override
			public void run() {
				geneItems();
				mAdapter.notifyDataSetChanged();
				onLoad();
			}
		}, 2000);
	}

}

 重要的代碼都總結在這了，希望給大家帶來幫助，謝謝。