ListView下拉刷新、上拉载入更多之封装改进

在Android中ListView下拉刷新、上拉载入更多示例一文中，Maxwin兄给出的控件比较强大，前面有详细介绍，但是有个不足就是，里面使用了一些资源文件，包括图片，String，layout，这样不利于封装打包，下面我将源码进行改进，所有布局全部用代码实现，这样直接将src和assets打包成jar就成了一个非常方便以后使用的扩展ListView控件，代码如下：

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) { // 未处于刷新状态，更新箭头
            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("数据监测：" + 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("松开载入更多");
        } 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));
        // 将根布局加到该LinearLayout中
        addView(moreView);

        // 根布局里面的相对布局
        mContentView = new RelativeLayout(mContext);
        LinearLayout.LayoutParams linearLp1 = new LinearLayout.LayoutParams(
                LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        mContentView.setPadding(10, 10, 10, 10);
        // 将相对布局relayout加到moreView根布局中
        moreView.addView(mContentView, linearLp1);

        // 进度条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);
        // 将mProgressBar加入相对布局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);
        // 将其加入相对布局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);
        // 初始情况，设置下拉刷新view高度为0
        LinearLayout.LayoutParams linearLp1 = new LinearLayout.LayoutParams(
                LayoutParams.MATCH_PARENT, 0);
        // 将根布局加入该LinearLayout中
        addView(mContainer, linearLp1);
        setGravity(Gravity.BOTTOM);

        // 里面的相对布局
        RelativeLayout relayout = new RelativeLayout(context);
        relayout.setId(RELAYOUT_ID);
        LinearLayout.LayoutParams linearLp2 = new LinearLayout.LayoutParams(
                LayoutParams.MATCH_PARENT, 60);
        // 将里面的相对布局加入根布局中
        mContainer.addView(relayout, linearLp2);

        // 相对布局里的子线性布局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);
        // 将子布局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);
        // 将TextView加入linear1中
        linear1.addView(mHintTextView, linearLp3);

        // 子线性布局1（linear1）里的线性布局linear12
        LinearLayout linear12 = new LinearLayout(context);
        LinearLayout.LayoutParams linearLp4 = new LinearLayout.LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        linearLp4.setMargins(0, 3, 0, 0);
        // 将linear12加入linear1中
        linear1.addView(linear12, linearLp4);

        // 提示时间TextView
        TextView tv = new TextView(context);
        tv.setText("上次更新时间：");
        tv.setTextSize(12);
        // 将提示时间TextView加入linear12
        linear12.addView(tv, linearLp3);

        // 时间值TextView
        TextView tv2 = new TextView(context);
        tv2.setId(HEAD_TIME_VIEW_ID);
        tv2.setTextSize(12);
        // 将时间值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));
        // 将ImageView加到相对布局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);
        // 将mProgressBar加到相对布局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) { // 显示进度
            mArrowImageView.clearAnimation();
            mArrowImageView.setVisibility(View.INVISIBLE);
            mProgressBar.setVisibility(View.VISIBLE);
        } else { // 显示箭头图片
            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("松开刷新数据");
            }
            break;
        case STATE_REFRESHING:
            mHintTextView.setText("正在加载...");
            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();
    }

    /**
     * 读取assets里面文件名为xlistview_arrow.png的图片
     *
     * @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;
    }

}

然后将使用到的那张图片放在assets目录下和src一起打包即可。