step1:新建项目 PullToRefresh
step2:设计应用的UI界面
a./layout/pull_to_refresh.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <!-- The PullToRefreshListView replaces a standard ListView widget. --> <cn.roco.refresh.PullToRefreshListView android:id="@+id/android:list" android:layout_height="fill_parent" android:layout_width="fill_parent" /> </LinearLayout>
b./layout/pull_to_refresh_header.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:paddingTop="10dip" android:paddingBottom="15dip" android:gravity="center" android:id="@+id/pull_to_refresh_header"> <ProgressBar android:id="@+id/pull_to_refresh_progress" android:indeterminate="true" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="30dip" android:layout_marginRight="20dip" android:layout_marginTop="10dip" android:visibility="gone" android:layout_centerVertical="true" style="?android:attr/progressBarStyleSmall" /> <ImageView android:id="@+id/pull_to_refresh_image" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="30dip" android:layout_marginRight="20dip" android:visibility="gone" android:layout_gravity="center" android:gravity="center" android:src="@drawable/ic_pulltorefresh_arrow" /> <TextView android:id="@+id/pull_to_refresh_text" android:text="@string/pull_to_refresh_tap_label" android:textAppearance="?android:attr/textAppearanceMedium" android:textStyle="bold" android:paddingTop="5dip" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center" android:gravity="center" /> <TextView android:id="@+id/pull_to_refresh_updated_at" android:layout_below="@+id/pull_to_refresh_text" android:visibility="gone" android:textAppearance="?android:attr/textAppearanceSmall" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center" android:gravity="center" /> </RelativeLayout>
step3:cn.roco.refreshPullToRefreshListView.java 该类重写了ListView
package cn.roco.refresh;
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.ImageView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.AbsListView.OnScrollListener;
public class PullToRefreshListView extends ListView implements OnScrollListener {
private static final int TAP_TO_REFRESH = 1; // 初始状态
private static final int PULL_TO_REFRESH = 2; // 拉动刷新
private static final int RELEASE_TO_REFRESH = 3; // 释放刷新
private static final int REFRESHING = 4; // 正在刷新
private static final String TAG = "PullToRefreshListView";
private OnRefreshListener mOnRefreshListener; // 刷新接口
/**
* Listener that will receive notifications every time the list scrolls.
*/
private OnScrollListener mOnScrollListener; // listview 滚动监听器
private LayoutInflater mInflater; // 视图索引器
/**
* 头部视图 内容 -- start
*/
private RelativeLayout mRefreshView;
private TextView mRefreshViewText;
private ImageView mRefreshViewImage;
private ProgressBar mRefreshViewProgress; // 刷新进度
private TextView mRefreshViewLastUpdated;
/**
* 头部视图 内容 -- end
*/
private int mCurrentScrollState; // 当前listivew 的滚动状态
private int mRefreshState; // 当前listview 的刷新状态
// 动画效果
private RotateAnimation mFlipAnimation; // 变为向下的箭头
private RotateAnimation mReverseFlipAnimation; // 变为逆向的箭头
private int mRefreshViewHeight; // 头视图的高度
private int mRefreshOriginalTopPadding; // 头视图 原始的top padding 属性值
private int mLastMotionY; // 向下触屏事件时的手指起始y轴位置
private boolean mBounceHack; // 是否反弹
public PullToRefreshListView(Context context) {
super(context);
init(context);
}
public PullToRefreshListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public PullToRefreshListView(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
init(context);
}
private void init(Context context) {
// Load all of the animations we need in code rather than through XML
// 初始化动画
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);
mInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mRefreshView = (RelativeLayout) mInflater.inflate(
R.layout.pull_to_refresh_header, this, false);
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);
mRefreshViewImage.setMinimumHeight(50);
mRefreshView.setOnClickListener(new OnClickRefreshListener());
mRefreshOriginalTopPadding = mRefreshView.getPaddingTop();
mRefreshState = TAP_TO_REFRESH;
addHeaderView(mRefreshView);
super.setOnScrollListener(this);
measureView(mRefreshView);
mRefreshViewHeight = mRefreshView.getMeasuredHeight(); // 获取头文件的测量高度
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
setSelection(1);
}
@Override
public void setAdapter(ListAdapter adapter) {
super.setAdapter(adapter);
setSelection(1);
}
/**
* Set the listener that will receive notifications every time the list
* scrolls.
*
* @param l
* The scroll listener.
*/
@Override
public void setOnScrollListener(AbsListView.OnScrollListener l) {
mOnScrollListener = l;
}
/**
* 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;
}
/**
* 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);
}
}
/**
* 触摸事件
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
final int y = (int) event.getY(); // 当前手指的Y值
mBounceHack = false; // 不反弹
switch (event.getAction()) {
case MotionEvent.ACTION_UP:
// 将垂直滚动条设置为可用状态
if (!isVerticalScrollBarEnabled()) {
setVerticalScrollBarEnabled(true);
}
// 如果头部刷新条出现，并且不是正在刷新状态
if (getFirstVisiblePosition() == 0 && mRefreshState != REFRESHING) {
if ((mRefreshView.getBottom() >= mRefreshViewHeight || mRefreshView
.getTop() >= 0) && mRefreshState == RELEASE_TO_REFRESH) { // 如果头部视图处于拉离顶部的情况
// Initiate the refresh
mRefreshState = REFRESHING; // 将标量设置为，正在刷新
prepareForRefresh(); // 准备刷新
onRefresh(); // 刷新
} else if (mRefreshView.getBottom() < mRefreshViewHeight
|| mRefreshView.getTop() <= 0) {
// Abort refresh and scroll down below the refresh view
// 停止刷新，并且滚动到头部刷新视图的下一个视图
resetHeader();
setSelection(1);// 定位在第二个列表项
}
}
break;
case MotionEvent.ACTION_DOWN:
mLastMotionY = y; // 跟踪手指的Y值
break;
case MotionEvent.ACTION_MOVE:
applyHeaderPadding(event); // 更行头视图的toppadding 属性
break;
}
return super.onTouchEvent(event);
}
/****
* 不断的头部的top padding 属性
*
* @param ev
*/
private void applyHeaderPadding(MotionEvent ev) {
// getHistorySize has been available since API 1
int pointerCount = ev.getHistorySize(); // 获取累积的动作数
for (int p = 0; p < pointerCount; p++) {
if (mRefreshState == RELEASE_TO_REFRESH) { // 如果是释放将要刷新状态
if (isVerticalFadingEdgeEnabled()) {
setVerticalScrollBarEnabled(false);
}
int historicalY = (int) ev.getHistoricalY(p); // 历史累积的高度
// Calculate the padding to apply, we divide by 1.7 to
// simulate a more resistant effect during pull.
int topPadding = (int) (((historicalY - mLastMotionY) - mRefreshViewHeight) / 1.7);
mRefreshView.setPadding(mRefreshView.getPaddingLeft(),
topPadding, mRefreshView.getPaddingRight(),
mRefreshView.getPaddingBottom());
}
}
}
/**
* Sets the header padding back to original size. 使头部视图的toppadding 恢复到初始值
*/
private void resetHeaderPadding() {
mRefreshView.setPadding(mRefreshView.getPaddingLeft(),
mRefreshOriginalTopPadding, mRefreshView.getPaddingRight(),
mRefreshView.getPaddingBottom());
}
/**
* Resets the header to the original state. 初始化头部视图 状态
*/
private void resetHeader() {
if (mRefreshState != TAP_TO_REFRESH) {
mRefreshState = TAP_TO_REFRESH; // 初始刷新状态
resetHeaderPadding(); // 使头部视图的toppadding 恢复到初始值
// Set refresh view text to the pull label
mRefreshViewText.setText(R.string.pull_to_refresh_tap_label); // 将文字初始化
// Replace refresh drawable with arrow drawable
mRefreshViewImage
.setImageResource(R.drawable.ic_pulltorefresh_arrow); // 设置初始图片
// Clear the full rotation animation
mRefreshViewImage.clearAnimation(); // 清除动画
// Hide progress bar and arrow.
mRefreshViewImage.setVisibility(View.GONE); // 隐藏头视图
mRefreshViewProgress.setVisibility(View.GONE); // 隐藏进度条
}
}
// 测量视图的高度
private void measureView(View child) {
// 获取头部视图属性
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) {// 如果视图的高度大于0
childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,
MeasureSpec.EXACTLY);
} else {
childHeightSpec = MeasureSpec.makeMeasureSpec(0,
MeasureSpec.UNSPECIFIED);
}
child.measure(childWidthSpec, childHeightSpec);
}
/****
* 滑动事件 滑动时被调用
*/
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// When the refresh view is completely visible, change the text to say
// "Release to refresh..." and flip the arrow drawable.
// 如果是接触滚动状态,并且不是正在刷新的状态
if (mCurrentScrollState == SCROLL_STATE_TOUCH_SCROLL
&& mRefreshState != REFRESHING) {
if (firstVisibleItem == 0) { // 如果显示出来了第一个列表项
// 显示刷新图片
mRefreshViewImage.setVisibility(View.VISIBLE);
if ((mRefreshView.getBottom() >= mRefreshViewHeight + 20 || mRefreshView
.getTop() >= 0) && mRefreshState != RELEASE_TO_REFRESH) { // 如果下拉了listiview,则显示上拉刷新动画
mRefreshViewText
.setText(R.string.pull_to_refresh_release_label);
mRefreshViewImage.clearAnimation();
mRefreshViewImage.startAnimation(mFlipAnimation);
mRefreshState = RELEASE_TO_REFRESH;
} else if (mRefreshView.getBottom() < mRefreshViewHeight + 20
&& mRefreshState != PULL_TO_REFRESH) { // 如果没有到达，下拉刷新距离，则回归原来的状态
mRefreshViewText
.setText(R.string.pull_to_refresh_pull_label);
if (mRefreshState != TAP_TO_REFRESH) {
mRefreshViewImage.clearAnimation();
mRefreshViewImage.startAnimation(mReverseFlipAnimation);
}
mRefreshState = PULL_TO_REFRESH;
}
} else {
mRefreshViewImage.setVisibility(View.GONE); // 隐藏刷新图片
resetHeader(); // 初始化，头部
}
}
// 如果是自己滚动状态+ 第一个视图已经显示+ 不是刷新状态
else if (mCurrentScrollState == SCROLL_STATE_FLING
&& firstVisibleItem == 0 && mRefreshState != REFRESHING) {
setSelection(1);
mBounceHack = true; // 状态为回弹
} else if (mBounceHack && mCurrentScrollState == SCROLL_STATE_FLING) {
setSelection(1);
}
if (mOnScrollListener != null) {
mOnScrollListener.onScroll(view, firstVisibleItem,
visibleItemCount, totalItemCount);
}
}
/**
* 滑动状态改变时被调用
*/
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
mCurrentScrollState = scrollState;
if (mCurrentScrollState == SCROLL_STATE_IDLE) { // 如果滚动停顿
mBounceHack = false;
}
if (mOnScrollListener != null) {
mOnScrollListener.onScrollStateChanged(view, scrollState);
}
}
// 准备刷新
public void prepareForRefresh() {
resetHeaderPadding(); // 初始化，头部文件
mRefreshViewImage.setVisibility(View.GONE);
// We need this hack, otherwise it will keep the previous drawable.
mRefreshViewImage.setImageDrawable(null);
mRefreshViewProgress.setVisibility(View.VISIBLE);
// Set refresh view text to the refreshing label
mRefreshViewText.setText(R.string.pull_to_refresh_refreshing_label);
mRefreshState = REFRESHING;
}
// 刷新
public void onRefresh() {
Log.d(TAG, "onRefresh");
if (mOnRefreshListener != null) {
mOnRefreshListener.onRefresh();
}
}
/**
* 刷新完成 的回调函数 Resets the list to a normal state after a refresh.
*
* @param lastUpdated
* Last updated at.
*/
public void onRefreshComplete(CharSequence lastUpdated) {
setLastUpdated(lastUpdated);
onRefreshComplete();
}
/**
* 刷新完成回调函数 Resets the list to a normal state after a refresh.
*/
public void onRefreshComplete() {
Log.d(TAG, "onRefreshComplete");
resetHeader();
// If refresh view is visible when loading completes, scroll down to
// the next item.
if (mRefreshView.getBottom() > 0) {
invalidateViews();
setSelection(1);
}
}
/**
* Invoked when the refresh view is clicked on. This is mainly used when
* there's only a few items in the list and it's not possible to drag the
* list.
*/
private class OnClickRefreshListener implements OnClickListener {
@Override
public void onClick(View v) {
if (mRefreshState != REFRESHING) {
prepareForRefresh();
onRefresh();
}
}
}
/**
* 刷新方法接口 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();
}
}
step4:PullToRefreshActivity.java
package cn.roco.refresh;
import java.util.Arrays;
import java.util.LinkedList;
import android.app.ListActivity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import cn.roco.refresh.PullToRefreshListView.OnRefreshListener;
public class PullToRefreshActivity extends ListActivity {
private LinkedList<String> mListItems;
private String[] mStrings;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.pull_to_refresh);
mStrings = initString();
// Set a listener to be invoked when the list should be refreshed.
((PullToRefreshListView) getListView())
.setOnRefreshListener(new OnRefreshListener() {
@Override
public void onRefresh() {
// Do work to refresh the list here.
new GetDataTask().execute();
}
});
mListItems = new LinkedList<String>();
mListItems.addAll(Arrays.asList(mStrings));
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, mListItems);
setListAdapter(adapter);
}
private class GetDataTask extends AsyncTask<Void, Void, String[]> {
@Override
protected String[] doInBackground(Void... params) {
// Simulates a background job.
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
;
}
return mStrings;
}
@Override
protected void onPostExecute(String[] result) {
mListItems.addFirst("Added after refresh...");
// Call onRefreshComplete when the list has been refreshed.
((PullToRefreshListView) getListView()).onRefreshComplete();
super.onPostExecute(result);
}
}
private String[] initString() {
String[] initStrings = new String[20];
for (int i = 0; i < initStrings.length; i++) {
initStrings[i] = "Roco_" + i;
}
return initStrings;
}
}
step5:部署应用，查看运行效果
==================================下面看一个gif动画===========================================
注：（原作者：johannilsson 选自：https://github.com/johannilsson/android-pulltorefresh）
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作者：欧阳鹏 欢迎转载，与人分享是进步的源泉！
转载请保留原文地址：http://blog.csdn.net/ouyang_peng
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