android 之下拉刷新

时间：2016-01-16 19:11:21 阅读：221 评论：0 收藏：0 [点我收藏+]

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一.概述

Android 下拉刷新几乎是每个应用都必带的功能, 并且现在下拉刷新第三方库也越来越多了,很方便就能实现该功能, 下面我介绍一下自己常用的几个方法.

二.例子

第一种方式:就是集成ListView实现自定义控件完成上下拉刷新

public class PullToRefreshListView extends ListView implements OnScrollListener, OnClickListener {
    /**
     * 下拉状态
     */
    private static final int PULL_TO_REFRESH = 1;   //下拉-默认为初始状态  准备下拉刷新
    private static final int RELEASE_TO_REFRESH = 2;   //释放刷新
    private static final int REFRESHING = 3;       //正在刷新

    private static final String TAG = "PullRefreshListView";

    private OnRefreshListener mOnRefreshListener;

    /**
     * 组件滑动监听器 scroll  当view在进行下拉滑动的时候，判断滑动的距离，
     * 如果达到可以进行刷新的临界点时候，回调当前接口中的方法
     * Listener that will receive notifications every time the list scrolls.
     */
    private OnScrollListener mOnScrollListener;

    //下拉刷新的的头部view
    private LinearLayout mRefreshView;
    private ImageView mRefreshViewImage;
    private ProgressBar mRefreshViewProgress;
    private TextView mRefreshViewText;
    private TextView mRefreshViewLastUpdated;


    private int mRefreshState;
    private int mCurrentScrollState;

    private RotateAnimation mFlipAnimation;
    private RotateAnimation mReverseFlipAnimation;

    private int mRefreshViewHeight;
    private int mRefreshOriginalTopPadding;
    private int mLastMotionY;

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

    public PullToRefreshListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    private void init(Context context) {
        mFlipAnimation = new RotateAnimation(0, -180,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);
        mFlipAnimation.setInterpolator(new LinearInterpolator());
        mFlipAnimation.setDuration(250);
        mFlipAnimation.setFillAfter(true);
        mReverseFlipAnimation = new RotateAnimation(-180, 0,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);
        mReverseFlipAnimation.setInterpolator(new LinearInterpolator());
        mReverseFlipAnimation.setDuration(250);
        mReverseFlipAnimation.setFillAfter(true);

        mRefreshView = (LinearLayout) View.inflate(context, R.layout.pull_to_refresh_header, null);
        mRefreshViewText = (TextView) mRefreshView.findViewById(R.id.pull_to_refresh_text);
        mRefreshViewImage = (ImageView) mRefreshView.findViewById(R.id.pull_to_refresh_image);
        mRefreshViewProgress = (ProgressBar) mRefreshView.findViewById(R.id.pull_to_refresh_progress);
        mRefreshViewLastUpdated = (TextView) mRefreshView.findViewById(R.id.pull_to_refresh_updated_at);

        mRefreshState = PULL_TO_REFRESH;
        mRefreshViewImage.setMinimumHeight(50); //设置下拉最小的高度为50
        
        setFadingEdgeLength(0);
        setHeaderDividersEnabled(false);

        //把refreshview加入到listview的头部
        addHeaderView(mRefreshView);
        super.setOnScrollListener(this);
        mRefreshView.setOnClickListener(this);

        mRefreshView.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
        mRefreshViewHeight = mRefreshView.getMeasuredHeight();
        mRefreshOriginalTopPadding = -mRefreshViewHeight;
        
        resetHeaderPadding();
    }

    /**
     * Set the listener that will receive notifications every time the list scrolls.
     * 
     * @param l  The scroll listener.
     */
    @Override
    public void setOnScrollListener(OnScrollListener l) {
        mOnScrollListener = l;
    }

    /**
     * 注册listview下拉刷新回到接口
     * Register a callback to be invoked when this list should be refreshed.
     * 
     * @param onRefreshListener  The callback to run.
     */
    public void setOnRefreshListener(OnRefreshListener onRefreshListener) {
        mOnRefreshListener = onRefreshListener;
    }

     /**
      * 进行设置设置上一次更新的时候
      *
     * Set a text to represent when the list was last updated. 
     * @param lastUpdated Last updated at.
     */
    public void setLastUpdated(CharSequence lastUpdated) {
        if (lastUpdated != null) {
            mRefreshViewLastUpdated.setVisibility(View.VISIBLE);
            mRefreshViewLastUpdated.setText(lastUpdated);
        } else {
            mRefreshViewLastUpdated.setVisibility(View.GONE);
        }
    }

    /**
     * touch事件处理
     * @param event
     * @return
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        final int y = (int) event.getY();
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            mLastMotionY = y;
            break;
        case MotionEvent.ACTION_MOVE:
            int offsetY = (int) event.getY();
            int deltY = Math.round(offsetY - mLastMotionY);
            mLastMotionY = offsetY;

            if (getFirstVisiblePosition() == 0 && mRefreshState != REFRESHING) {
                deltY = deltY / 2;
                mRefreshOriginalTopPadding += deltY;
                if (mRefreshOriginalTopPadding < -mRefreshViewHeight) {
                    mRefreshOriginalTopPadding = -mRefreshViewHeight;
                }
                resetHeaderPadding();
            }
            break;
        case MotionEvent.ACTION_UP:
            //当手指抬开得时候 进行判断下拉的距离 ，如果>=临界值，那么进行刷洗，否则回归原位
            if (!isVerticalScrollBarEnabled()) {
                setVerticalScrollBarEnabled(true);
            }
            if (getFirstVisiblePosition() == 0 && mRefreshState != REFRESHING) {
                if (mRefreshView.getBottom() >= mRefreshViewHeight 
                        && mRefreshState == RELEASE_TO_REFRESH) {
                    //准备开始刷新
                    prepareForRefresh();
                } else {
                    // Abort refresh
                    resetHeader();
                }
            }
            break;
        }
        return super.onTouchEvent(event);
    }
    
    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        if (mCurrentScrollState == SCROLL_STATE_TOUCH_SCROLL && mRefreshState != REFRESHING) {
             if (firstVisibleItem == 0) {
                if ((mRefreshView.getBottom() >= mRefreshViewHeight)
                        && mRefreshState != RELEASE_TO_REFRESH) {
                    mRefreshViewText.setText(R.string.pull_to_refresh_release_label_it);
                    mRefreshViewImage.clearAnimation();
                    mRefreshViewImage.startAnimation(mFlipAnimation);
                    mRefreshState = RELEASE_TO_REFRESH;
                } else if (mRefreshView.getBottom() < mRefreshViewHeight
                        && mRefreshState != PULL_TO_REFRESH) {
                    mRefreshViewText.setText(R.string.pull_to_refresh_pull_label_it);
                    mRefreshViewImage.clearAnimation();
                    mRefreshViewImage.startAnimation(mReverseFlipAnimation);
                    mRefreshState = PULL_TO_REFRESH;
                }
            }
        }
        
        if (mOnScrollListener != null) {
            mOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
        }
    }

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

    /**
     * Sets the header padding back to original size.
     */
    private void resetHeaderPadding() {
        mRefreshView.setPadding(
                mRefreshView.getPaddingLeft(),
                mRefreshOriginalTopPadding,
                mRefreshView.getPaddingRight(),
                mRefreshView.getPaddingBottom());
    }

    public void prepareForRefresh() {
        if (mRefreshState != REFRESHING) {
            mRefreshState = REFRESHING;
            
            mRefreshOriginalTopPadding = 0;
            resetHeaderPadding();
            
            mRefreshViewImage.clearAnimation();
            mRefreshViewImage.setVisibility(View.GONE);
            mRefreshViewProgress.setVisibility(View.VISIBLE);
            mRefreshViewText.setText(R.string.pull_to_refresh_refreshing_label_it);
            
            onRefresh();
        }
    }

    private void resetHeader() {
        mRefreshState = PULL_TO_REFRESH;
        
        mRefreshOriginalTopPadding = -mRefreshViewHeight;
        resetHeaderPadding();
        
        mRefreshViewImage.clearAnimation();
        mRefreshViewImage.setVisibility(View.VISIBLE);
        mRefreshViewProgress.setVisibility(View.GONE);
        mRefreshViewText.setText(R.string.pull_to_refresh_pull_label_it);
    }

    /**
     * 开始回调刷新
     */
    public void onRefresh() {
        Log.d(TAG, "onRefresh");
        if (mOnRefreshListener != null) {
            mOnRefreshListener.onRefresh();
        }
    }
    
    /**
     * Resets the list to a normal state after a refresh.
     */
    public void onRefreshComplete() {        
        Log.d(TAG, "onRefreshComplete");

        resetHeader();
    }
    
    @Override
    public void onClick(View v) {
        Log.d(TAG, "onClick");
    }
    
    /**
     * Interface definition for a callback to be invoked when list should be
     * refreshed.
     */
    public interface OnRefreshListener {
        /**
         * Called when the list should be refreshed.
         * <p>
         * A call to {@link PullToRefreshListView #onRefreshComplete()} is
         * expected to indicate that the refresh has completed.
         */
        public void onRefresh();
    }
}

上面代码就完成了,上下拉刷新工作, 直接拷贝到工程无需任何修改就可使用

当然它还需一个"头布局"

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pull_to_refresh_header"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="#F3F3F3"
    android:orientation="vertical" >
    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingTop="23dip" >
        <LinearLayout
            android:id="@+id/pull_to_refresh_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:orientation="vertical" >
            <TextView
                android:id="@+id/pull_to_refresh_text"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:gravity="center"
                android:text="@string/pull_to_refresh_pull_label"
                android:textColor="#777777"
                android:textSize="16sp" />
            <TextView
                android:id="@+id/pull_to_refresh_updated_at"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:gravity="center"
                android:text="@string/pull_to_refresh_updated_at"
                android:textColor="#999999"
                android:textSize="14sp" />
        </LinearLayout>
        <ProgressBar
            android:id="@+id/pull_to_refresh_progress"
            android:layout_width="30dip"
            android:layout_height="30dip"
            android:layout_marginRight="22dip"
            android:layout_marginTop="5dip"
            android:layout_toLeftOf="@+id/pull_to_refresh_view"
            android:indeterminate="true"
            android:indeterminateDrawable="@anim/ic_loading_refresh"
            android:visibility="gone" />
        <ImageView
            android:id="@+id/pull_to_refresh_image"
            android:layout_width="32dip"
            android:layout_height="32dip"
            android:layout_marginRight="20dip"
            android:layout_marginTop="5dip"
            android:layout_toLeftOf="@+id/pull_to_refresh_view"
            android:contentDescription="@string/app_name"
            android:gravity="center"
            android:src="@drawable/ic_refresh_down" />
    </RelativeLayout>
    <View
        android:layout_width="fill_parent"
        android:layout_height="15dip" />
</LinearLayout>

此外代码中还用到了时间的工具类: 如下

public class SharedPreferencesHelper {
    private static final String SHARED_PATH = "fda_shared";
    private static SharedPreferencesHelper instance;
    private SharedPreferences sp;
    private SharedPreferences.Editor editor;

    public static SharedPreferencesHelper getInstance(Context context) {
        if (instance == null && context != null) {
            instance = new SharedPreferencesHelper(context);
        }
        return instance;
    }

    private SharedPreferencesHelper(Context context) {
        sp = context.getSharedPreferences(SHARED_PATH, Context.MODE_PRIVATE);
        editor = sp.edit();
    }

    public long getLongValue(String key) {
        if (key != null && !key.equals("")) {
            return sp.getLong(key, 0);
        }
        return 0;
    }

    public String getStringValue(String key) {
        if (key != null && !key.equals("")) {
            return sp.getString(key, null);
        }
        return null;
    }

    public int getIntValue(String key) {
        if (key != null && !key.equals("")) {
            return sp.getInt(key, 0);
        }
        return 0;
    }

    public int getIntValueByDefault(String key)
    {
        if (key != null && !key.equals("")) {
            return sp.getInt(key, 0);
        }
        return 0;
    }
    public boolean getBooleanValue(String key) {
        if (key != null && !key.equals("")) {
            return sp.getBoolean(key, false);
        }
        return true;
    }

    public float getFloatValue(String key) {
        if (key != null && !key.equals("")) {
            return sp.getFloat(key, 0);
        }
        return 0;
    }

    public void putStringValue(String key, String value) {
        if (key != null && !key.equals("")) {
            editor = sp.edit();
            editor.putString(key, value);
            editor.commit();
        }
    }

    public void putIntValue(String key, int value) {
        if (key != null && !key.equals("")) {
            editor = sp.edit();
            editor.putInt(key, value);
            editor.commit();
        }
    }

    public void putBooleanValue(String key, boolean value) {
        if (key != null && !key.equals("")) {
            editor = sp.edit();
            editor.putBoolean(key, value);
            editor.commit();
        }
    }

    public void putLongValue(String key, long value) {
        if (key != null && !key.equals("")) {
            editor = sp.edit();
            editor.putLong(key, value);
            editor.commit();
        }
    }

    public void putFloatValue(String key, Float value) {
        if (key != null && !key.equals("")) {
            editor = sp.edit();
            editor.putFloat(key, value);
            editor.commit();
        }
    }
}

public class SharedPreferencesTag {
    public static final String DEMO_KEY="demo_key";

}

public class UIUtils {

    /**
     * 设置上次更新数据时间
     * @param listView
     * @param key key表示具体某个列表
     */
    public static void setPullToRefreshLastUpdated(PullToRefreshListView listView, String key,Context pContext) {
        SharedPreferencesHelper spHelper = SharedPreferencesHelper.getInstance(pContext);
        long lastUpdateTimeStamp = spHelper.getLongValue(key);
        listView.setLastUpdated(getUpdateTimeString(lastUpdateTimeStamp));
    }

    /**
     * 保存更新数据时间
     * @param listView
     * @param key key表示具体某个列表
     */
    public static void savePullToRefreshLastUpdateAt(PullToRefreshListView listView, String key,Context pContext) {
        listView.onRefreshComplete();
        SharedPreferencesHelper spHelper = SharedPreferencesHelper.getInstance(pContext);
        long lastUpdateTimeStamp=System.currentTimeMillis();
        spHelper.putLongValue(key, lastUpdateTimeStamp);
        listView.setLastUpdated(getUpdateTimeString(lastUpdateTimeStamp));
    }

    /**
     * 更新时间字符串
     * @param timestamp
     * @return
     */
    @SuppressLint("SimpleDateFormat")
    public static String getUpdateTimeString(long timestamp) {
        if (timestamp <= 0) {
            return "上次更新时间:";
        } else {
            String textDate = "上次更新时间:";
            Calendar now = Calendar.getInstance();
            Calendar c = Calendar.getInstance();
            c.setTimeInMillis(timestamp);
            if (c.get(Calendar.YEAR) == now.get(Calendar.YEAR)
                    && c.get(Calendar.MONTH) == now.get(Calendar.MONTH)
                    && c.get(Calendar.DATE) == now.get(Calendar.DATE)) {
                SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
                return textDate += sdf.format(c.getTime());
            } else if (c.get(Calendar.YEAR) == now.get(Calendar.YEAR)) {
                SimpleDateFormat sdf = new SimpleDateFormat("MM/dd HH:mm");
                return textDate += sdf.format(c.getTime());
            } else {
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm");
                return textDate += sdf.format(c.getTime());
            }
        }
    }
}