Android自定义控件下拉刷新实例代码

<resources>  <string name="app_name">PullToRefreshTest</string>  <string name="pull_to_refresh">下拉可以刷新</string>  <string name="release_to_refresh">释放立即刷新</string>  <string name="refreshing">正在刷新...</string>  <string name="not_updated_yet">暂未更新过</string>  <string name="updated_at">上次更新于%1$s前</string>  <string name="updated_just_now">刚刚更新</string>  <string name="time_error">时间有问题</string></resources><?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:id="@+id/pull_to_refresh_head"  android:layout_width="match_parent"  android:layout_height="60dp">  <LinearLayout    android:layout_width="200dp"    android:layout_height="60dp"    android:layout_centerInParent="true"    android:orientation="horizontal">    <RelativeLayout      android:layout_width="0dp"      android:layout_height="60dp"      android:layout_weight="3">      <ImageView        android:id="@+id/arrow"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:src="@mipmap/indicator_arrow" />      <ProgressBar        android:id="@+id/progress_bar"        android:layout_width="30dp"        android:layout_height="30dp"        android:layout_centerInParent="true"        android:visibility="gone" />    </RelativeLayout>    <LinearLayout      android:layout_width="0dp"      android:layout_height="60dp"      android:layout_weight="12"      android:orientation="vertical">      <TextView        android:id="@+id/description"        android:layout_width="match_parent"        android:layout_height="0dp"        android:layout_weight="1"        android:gravity="center_horizontal|bottom"        android:text="@string/pull_to_refresh" />      <TextView        android:id="@+id/updated_at"        android:layout_width="match_parent"        android:layout_height="0dp"        android:layout_weight="1"        android:gravity="center_horizontal|top"        android:text="@string/updated_at" />    </LinearLayout>  </LinearLayout></RelativeLayout>

stringspull_to_refresh--> 然后, 也是主要的, 自定义下拉刷新的 View (包含下拉刷新所有操作) RefreshView.java:package com.dragon.android.tofreshlayout;import android.content.Context;import android.content.SharedPreferences;import android.os.AsyncTask;import android.os.SystemClock;import android.preference.PreferenceManager;import android.util.AttributeSet;import android.view.LayoutInflater;import android.view.MotionEvent;import android.view.View;import android.view.ViewConfiguration;import android.view.animation.RotateAnimation;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.TextView;public class RefreshView extends LinearLayout implements View.OnTouchListener {private static final String TAG = RefreshView.class.getSimpleName();public enum PULL_STATUS {STATUS_PULL_TO_REFRESH(0), // 下拉状态STATUS_RELEASE_TO_REFRESH(1), // 释放立即刷新状态STATUS_REFRESHING(2), // 正在刷新状态STATUS_REFRESH_FINISHED(3); // 刷新完成或未刷新状态private int status; // 状态PULL_STATUS(int value) {this.status = value;}public int getValue() {return this.status;}}// 下拉头部回滚的速度public static final int SCROLL_SPEED = -20;// 一分钟的毫秒值，用于判断上次的更新时间public static final long ONE_MINUTE = 60 * 1000;// 一小时的毫秒值，用于判断上次的更新时间public static final long ONE_HOUR = 60 * ONE_MINUTE;// 一天的毫秒值，用于判断上次的更新时间public static final long ONE_DAY = 24 * ONE_HOUR;// 一月的毫秒值，用于判断上次的更新时间public static final long ONE_MONTH = 30 * ONE_DAY;// 一年的毫秒值，用于判断上次的更新时间public static final long ONE_YEAR = 12 * ONE_MONTH;// 上次更新时间的字符串常量，用于作为 SharedPreferences 的键值private static final String UPDATED_AT = "updated_at";// 下拉刷新的回调接口private PullToRefreshListener mListener;private SharedPreferences preferences; // 用于存储上次更新时间private View header; // 下拉头的Viewprivate ListView listView; // 需要去下拉刷新的ListViewprivate ProgressBar progressBar; // 刷新时显示的进度条private ImageView arrow; // 指示下拉和释放的箭头private TextView description; // 指示下拉和释放的文字描述private TextView updateAt; // 上次更新时间的文字描述private MarginLayoutParams headerLayoutParams; // 下拉头的布局参数private long lastUpdateTime; // 上次更新时间的毫秒值// 为了防止不同界面的下拉刷新在上次更新时间上互相有冲突，使用id来做区分private int mId = -1;private int hideHeaderHeight; // 下拉头的高度/*** 当前处理什么状态，可选值有 STATUS_PULL_TO_REFRESH, STATUS_RELEASE_TO_REFRESH, STATUS_REFRESHING 和 STATUS_REFRESH_FINISHED*/private PULL_STATUS currentStatus = PULL_STATUS.STATUS_REFRESH_FINISHED;// 记录上一次的状态是什么，避免进行重复操作private PULL_STATUS lastStatus = currentStatus;private float yDown; // 手指按下时的屏幕纵坐标private int touchSlop; // 在被判定为滚动之前用户手指可以移动的最大值。private boolean loadOnce; // 是否已加载过一次layout，这里onLayout中的初始化只需加载一次private boolean ableToPull; // 当前是否可以下拉，只有ListView滚动到头的时候才允许下拉/*** 下拉刷新控件的构造函数，会在运行时动态添加一个下拉头的布局*/public RefreshView(Context context, AttributeSet attrs) {super(context, attrs);preferences = PreferenceManager.getDefaultSharedPreferences(context);header = LayoutInflater.from(context).inflate(R.layout.pull_to_refresh, null, true);progressBar = (ProgressBar) header.findViewById(R.id.progress_bar);arrow = (ImageView) header.findViewById(R.id.arrow);description = (TextView) header.findViewById(R.id.description);updateAt = (TextView) header.findViewById(R.id.updated_at);touchSlop = ViewConfiguration.get(context).getScaledTouchSlop();refreshUpdatedAtValue();setOrientation(VERTICAL);addView(header, 0);//Log.d(TAG, "RefreshView Constructor() getChildAt(0): " + getChildAt(0));//Log.d(TAG, "RefreshView Constructor() getChildAt(0): " + getChildAt(1));// listView = (ListView) getChildAt(1);// listView.setOnTouchListener(this);}/*** 进行一些关键性的初始化操作，比如：将下拉头向上偏移进行隐藏，给 ListView 注册 touch 事件*/@Overrideprotected void onLayout(boolean changed, int l, int t, int r, int b) {super.onLayout(changed, l, t, r, b);if (changed && !loadOnce) {hideHeaderHeight = -header.getHeight();headerLayoutParams = (MarginLayoutParams) header.getLayoutParams();headerLayoutParams.topMargin = hideHeaderHeight;listView = (ListView) getChildAt(1);//Log.d(TAG, "onLayout() getChildAt(0): " + getChildAt(0));//Log.d(TAG, "onLayout() listView: " + listView);listView.setOnTouchListener(this);loadOnce = true;}}/*** 当 ListView 被触摸时调用，其中处理了各种下拉刷新的具体逻辑*/@Overridepublic boolean onTouch(View v, MotionEvent event) {setCanAbleToPull(event); // 判断是否可以下拉if (ableToPull) {switch (event.getAction()) {case MotionEvent.ACTION_DOWN:yDown = event.getRawY();break;case MotionEvent.ACTION_MOVE:// 获取移动中的 Y 轴的位置float yMove = event.getRawY();// 获取从按下到移动过程中移动的距离int distance = (int) (yMove - yDown);// 如果手指是上滑状态，并且下拉头是完全隐藏的，就屏蔽下拉事件if (distance <= 0 && headerLayoutParams.topMargin <= hideHeaderHeight) {return false;}if (distance < touchSlop) {return false;}// 判断是否已经在刷新状态if (currentStatus != PULL_STATUS.STATUS_REFRESHING) {// 判断设置的 topMargin 是否 > 0, 默认初始设置为 -header.getHeight()if (headerLayoutParams.topMargin > 0) {currentStatus = PULL_STATUS.STATUS_RELEASE_TO_REFRESH;} else {// 否则状态为下拉中的状态currentStatus = PULL_STATUS.STATUS_PULL_TO_REFRESH;}// 通过偏移下拉头的 topMargin 值，来实现下拉效果headerLayoutParams.topMargin = (distance / 2) + hideHeaderHeight;header.setLayoutParams(headerLayoutParams);}break;case MotionEvent.ACTION_UP:default:if (currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {// 松手时如果是释放立即刷新状态，就去调用正在刷新的任务new RefreshingTask().execute();} else if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH) {// 松手时如果是下拉状态，就去调用隐藏下拉头的任务new HideHeaderTask().execute();}break;}// 时刻记得更新下拉头中的信息if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH|| currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {updateHeaderView();// 当前正处于下拉或释放状态，要让 ListView 失去焦点，否则被点击的那一项会一直处于选中状态listView.setPressed(false);listView.setFocusable(false);listView.setFocusableInTouchMode(false);lastStatus = currentStatus;// 当前正处于下拉或释放状态，通过返回 true 屏蔽掉 ListView 的滚动事件return true;}}return false;}/*** 给下拉刷新控件注册一个监听器** @param listener 监听器的实现* @param id 为了防止不同界面的下拉刷新在上次更新时间上互相有冲突，不同界面在注册下拉刷新监听器时一定要传入不同的 id*/public void setOnRefreshListener(PullToRefreshListener listener, int id) {mListener = listener;mId = id;}/*** 当所有的刷新逻辑完成后，记录调用一下，否则你的 ListView 将一直处于正在刷新状态*/public void finishRefreshing() {currentStatus = PULL_STATUS.STATUS_REFRESH_FINISHED;preferences.edit().putLong(UPDATED_AT + mId, System.currentTimeMillis()).commit();new HideHeaderTask().execute();}/*** 根据当前 ListView 的滚动状态来设定 {@link #ableToPull}* 的值，每次都需要在 onTouch 中第一个执行，这样可以判断出当前应该是滚动 ListView，还是应该进行下拉*/private void setCanAbleToPull(MotionEvent event) {View firstChild = listView.getChildAt(0);if (firstChild != null) {// 获取 ListView 中第一个Item的位置int firstVisiblePos = listView.getFirstVisiblePosition();// 判断第一个子控件的 Top 是否和第一个 Item 位置相等if (firstVisiblePos == 0 && firstChild.getTop() == 0) {if (!ableToPull) {// getRawY() 获得的是相对屏幕 Y 方向的位置yDown = event.getRawY();}// 如果首个元素的上边缘，距离父布局值为 0，就说明 ListView 滚动到了最顶部，此时应该允许下拉刷新ableToPull = true;} else {if (headerLayoutParams.topMargin != hideHeaderHeight) {headerLayoutParams.topMargin = hideHeaderHeight;header.setLayoutParams(headerLayoutParams);}ableToPull = false;}} else {// 如果 ListView 中没有元素，也应该允许下拉刷新ableToPull = true;}}/*** 更新下拉头中的信息*/private void updateHeaderView() {if (lastStatus != currentStatus) {if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH) {description.setText(getResources().getString(R.string.pull_to_refresh));arrow.setVisibility(View.VISIBLE);progressBar.setVisibility(View.GONE);rotateArrow();} else if (currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {description.setText(getResources().getString(R.string.release_to_refresh));arrow.setVisibility(View.VISIBLE);progressBar.setVisibility(View.GONE);rotateArrow();} else if (currentStatus == PULL_STATUS.STATUS_REFRESHING) {description.setText(getResources().getString(R.string.refreshing));progressBar.setVisibility(View.VISIBLE);arrow.clearAnimation();arrow.setVisibility(View.GONE);}refreshUpdatedAtValue();}}/*** 根据当前的状态来旋转箭头*/private void rotateArrow() {float pivotX = arrow.getWidth() / 2f;float pivotY = arrow.getHeight() / 2f;float fromDegrees = 0f;float toDegrees = 0f;if (currentStatus == PULL_STATUS.STATUS_PULL_TO_REFRESH) {fromDegrees = 180f;toDegrees = 360f;} else if (currentStatus == PULL_STATUS.STATUS_RELEASE_TO_REFRESH) {fromDegrees = 0f;toDegrees = 180f;}RotateAnimation animation = new RotateAnimation(fromDegrees, toDegrees, pivotX, pivotY);animation.setDuration(100);animation.setFillAfter(true);arrow.startAnimation(animation);}/*** 刷新下拉头中上次更新时间的文字描述*/private void refreshUpdatedAtValue() {lastUpdateTime = preferences.getLong(UPDATED_AT + mId, -1);long currentTime = System.currentTimeMillis();long timePassed = currentTime - lastUpdateTime;long timeIntoFormat;String updateAtValue;if (lastUpdateTime == -1) {updateAtValue = getResources().getString(R.string.not_updated_yet);} else if (timePassed < 0) {updateAtValue = getResources().getString(R.string.time_error);} else if (timePassed < ONE_MINUTE) {updateAtValue = getResources().getString(R.string.updated_just_now);} else if (timePassed < ONE_HOUR) {timeIntoFormat = timePassed / ONE_MINUTE;String value = timeIntoFormat + "分钟";updateAtValue = String.format(getResources().getString(R.string.updated_at), value);} else if (timePassed < ONE_DAY) {timeIntoFormat = timePassed / ONE_HOUR;String value = timeIntoFormat + "小时";updateAtValue = String.format(getResources().getString(R.string.updated_at), value);} else if (timePassed < ONE_MONTH) {timeIntoFormat = timePassed / ONE_DAY;String value = timeIntoFormat + "天";updateAtValue = String.format(getResources().getString(R.string.updated_at), value);} else if (timePassed < ONE_YEAR) {timeIntoFormat = timePassed / ONE_MONTH;String value = timeIntoFormat + "个月";updateAtValue = String.format(getResources().getString(R.string.updated_at), value);} else {timeIntoFormat = timePassed / ONE_YEAR;String value = timeIntoFormat + "年";updateAtValue = String.format(getResources().getString(R.string.updated_at), value);}updateAt.setText(updateAtValue);}/*** 正在刷新的任务，在此任务中会去回调注册进来的下拉刷新监听器*/class RefreshingTask extends AsyncTask<Void, Integer, Void> {@Overrideprotected Void doInBackground(Void... params) {int topMargin = headerLayoutParams.topMargin;while (true) {topMargin = topMargin + SCROLL_SPEED;if (topMargin <= 0) {topMargin = 0;break;}publishProgress(topMargin);SystemClock.sleep(10);}currentStatus = PULL_STATUS.STATUS_REFRESHING;publishProgress(0);if (mListener != null) {mListener.onRefresh();}return null;}@Overrideprotected void onProgressUpdate(Integer... topMargin) {updateHeaderView();headerLayoutParams.topMargin = topMargin[0];header.setLayoutParams(headerLayoutParams);}}/*** 隐藏下拉头的任务，当未进行下拉刷新或下拉刷新完成后，此任务将会使下拉头重新隐藏*/class HideHeaderTask extends AsyncTask<Void, Integer, Integer> {@Overrideprotected Integer doInBackground(Void... params) {int topMargin = headerLayoutParams.topMargin;while (true) {topMargin = topMargin + SCROLL_SPEED;if (topMargin <= hideHeaderHeight) {topMargin = hideHeaderHeight;break;}publishProgress(topMargin);SystemClock.sleep(10);}return topMargin;}@Overrideprotected void onProgressUpdate(Integer ... topMargin) {headerLayoutParams.topMargin = topMargin[0];header.setLayoutParams(headerLayoutParams);}@Overrideprotected void onPostExecute(Integer topMargin) {headerLayoutParams.topMargin = topMargin;header.setLayoutParams(headerLayoutParams);currentStatus = PULL_STATUS.STATUS_REFRESH_FINISHED;}}/*** 下拉刷新的监听器，使用下拉刷新的地方应该注册此监听器来获取刷新回调*/public interface PullToRefreshListener {// 刷新时会去回调此方法，在方法内编写具体的刷新逻辑。注意此方法是在子线程中调用的， 可以不必另开线程来进行耗时操作void onRefresh();}}

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  tools:context=".MainActivity" >  <com.dragon.android.tofreshlayout.RefreshView    android:id="@+id/refreshable_view"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <ListView      android:id="@+id/list_view"      android:layout_width="match_parent"      android:layout_height="match_parent" >    </ListView>  </com.dragon.android.tofreshlayout.RefreshView></RelativeLayout>

package com.dragon.android.tofreshlayout;import android.os.Bundle;import android.os.SystemClock;import android.support.v7.app.AppCompatActivity;import android.webkit.WebView;import android.widget.ArrayAdapter;import android.widget.ListView;public class MainActivity extends AppCompatActivity {  RefreshView refreshableView;  ListView listView;  ArrayAdapter<String> adapter;  private WebView webView;  private static int NUM = 30;  String[] items = new String[NUM];  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    getSupportActionBar().hide();    for (int i = 0; i < items.length; i++) {      items[i] = "列表项" + i;    }    refreshableView = (RefreshView) findViewById(R.id.refreshable_view);    listView = (ListView) findViewById(R.id.list_view);    adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, items);    listView.setAdapter(adapter);    refreshableView.setOnRefreshListener(new RefreshView.PullToRefreshListener() {      @Override      public void onRefresh() {        SystemClock.sleep(3000);        refreshableView.finishRefreshing();      }    }, 0);  }}