在Android开发中有时我们须要訪问网络实时刷新数据。比方QQ好友在线状态最新信息,QQ空间须要显示很多其它的好友动态信息,EOE论坛client显示很多其它的文章帖子信息等。android-pulltorefresh开源项目提供一个向下滑动即刷新列表的功能,将该项目稍作改动就可以应用到自己的项目中。
1.下载地址
https://github.com/johannilsson/android-pulltorefresh
该项目为 Android 应用提供一个向下滑动即刷新列表的功能。
2.project组成
PullToRefreshListView.java
OnRefreshListener 监听刷新操作的接口 。onRefresh()刷新函数 在列表头部显示正在进行的刷新操作进度条
onRefreshComplete() 刷新操作完毕后。恢复列表常态
上述类和接口的详细实现:
public class PullToRefreshListView extends ListView implements OnScrollListener{ /**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(); } /** * Resets the list to a normal state after a refresh. * @param lastUpdated Last updated at. */ public void onRefreshComplete(CharSequence lastUpdated) { setLastUpdated(lastUpdated); onRefreshComplete(); } /** * 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 (getFirstVisiblePosition() == 0) { invalidateViews(); setSelection(1); } } }
pull_to_refresh_header.xml
PullToRefreshListView头部 显示刷新进度条信息 。在 PullToRefreshListView.java调用以下的语句将该子布局加入到列表顶部
private LayoutInflater mInflater;
private RelativeLayout mRefreshView;
mInflater = (LayoutInflater) context.getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
//header part of PullToRefreshListView
mRefreshView = (RelativeLayout) mInflater.inflate(R.layout.pull_to_refresh_header, this, false);
//add header part to the ListView
addHeaderView(mRefreshView);
PullToRefreshActivity.java (MainActivity)
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. --> <com.markupartist.android.widget.PullToRefreshListView android:id="@+id/android:list" android:layout_height="fill_parent" android:layout_width="fill_parent" /> </LinearLayout>注:
LiveActivity本身继承了关于List操作的众多接口,我们能够方便的重写这些操作中须要的方法来实现自己须要的功能。
假设要用ListActivity。则 Activity的Layout文件里必须包含一个(仅仅能一个)ListView。且ListView的id= "@id/android:list"。
3.PullToRefreshActivity.java
刷新额外的列表数据String mExtras[],当额外列表数据显示完成时。不再进行刷新操作。
比如以下这个样例刷新三次以后,就没有额外须要显示的数据。拉松列表进行刷新操作将提示“No More Messages”
package com.markupartist.android.example.pulltorefresh; import java.util.Arrays; import java.util.LinkedList; import android.annotation.SuppressLint; import android.app.ListActivity; import android.os.AsyncTask; import android.os.Bundle; import android.widget.ArrayAdapter; import android.widget.Toast; import com.markupartist.android.widget.PullToRefreshListView; import com.markupartist.android.widget.PullToRefreshListView.OnRefreshListener; @SuppressLint("NewApi") public class PullToRefreshActivity extends ListActivity { private LinkedList<String> mListItems; int count = 0; /** Called when the activity is first created. */ @SuppressLint("NewApi") @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.pull_to_refresh); // 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. if(count < mExtras.length) new GetDataTask().execute(count++); else{ Toast.makeText(getApplicationContext(), "No More Messages", Toast.LENGTH_LONG).show(); //Resets the list to a normal state after a refresh ((PullToRefreshListView) getListView()).onRefreshComplete(); } } }); 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<Integer, Void, String[]> { private int count; @Override protected String[] doInBackground(Integer... params) { count = params[0]; // Simulates a background job. try { Thread.sleep(2000); } catch (InterruptedException e) { ; } return mStrings; } @SuppressLint("NewApi") @Override protected void onPostExecute(String[] result) { // mListItems.addFirst("Added after refresh..."); mListItems.addFirst(mExtras[count]); // Call onRefreshComplete when the list has been refreshed. ((PullToRefreshListView) getListView()).onRefreshComplete(); // super.onPostExecute(result); } } private String[] mStrings = { "Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam", "Abondance", "Ackawi", "Acorn", "Adelost", "Affidelice au Chablis", "Afuega'l Pitu", "Airag", "Airedale", "Aisy Cendre", "Allgauer Emmentaler"}; private String[] mExtras = {"extra1","extra2","extra3"}; }
本文转自mfrbuaa博客园博客,原文链接:http://www.cnblogs.com/mfrbuaa/p/5090945.html,如需转载请自行联系原作者