Android开源项目PullToRefresh下拉刷新功能详解

先看看效果图：

开源项地址：https://github.com/chrisbanes/Android-PullToRefresh 

下拉刷新这个功能我们都比较常见了，今天介绍的就是这个功能的实现。我将按照这个开源库的范例来一点一点介绍，今天是介绍比较常见的PullToRefreshListView，是让listView有下拉刷新功能。 

1.下载项目包，将library包导入即可，其他的包暂时不用

2.分析源码，看我们可以设置的有哪些 

<?xml version="1.0" encoding="utf-8"?>
<resources>

<declare-styleable name="PullToRefresh">

<!-- A drawable to use as the background of the Refreshable View -->
<!-- 设置刷新view的背景 -->
<attr name="ptrRefreshableViewBackground" format="reference|color" />

<!-- A drawable to use as the background of the Header and Footer Loading Views -->
<!-- 设置头部view的背景 -->
<attr name="ptrHeaderBackground" format="reference|color" />

<!-- Text Color of the Header and Footer Loading Views -->
<!-- 设置头部/底部文字的颜色 -->
<attr name="ptrHeaderTextColor" format="reference|color" />

<!-- Text Color of the Header and Footer Loading Views Sub Header -->
<!-- 设置头部/底部副标题的文字颜色 -->
<attr name="ptrHeaderSubTextColor" format="reference|color" />

<!-- Mode of Pull-to-Refresh that should be used -->
<!-- 设置下拉刷新的模式，有多重方式可选。无刷新功能，从顶部刷新，从底部刷新，二者都有，只允许手动刷新 -->
<attr name="ptrMode">
 <flag name="disabled" value="0x0" />
 <flag name="pullFromStart" value="0x1" />
 <flag name="pullFromEnd" value="0x2" />
 <flag name="both" value="0x3" />
 <flag name="manualOnly" value="0x4" />

<!-- These last two are depreacted -->
 <!-- 这两个属性不推荐了，用上面的代替即可 -->
 <flag name="pullDownFromTop" value="0x1" />
 <flag name="pullUpFromBottom" value="0x2" />
</attr>

<!-- Whether the Indicator overlay(s) should be used -->
<!-- 是否显示指示箭头 -->
<attr name="ptrShowIndicator" format="reference|boolean" />

<!-- Drawable to use as Loading Indicator. Changes both Header and Footer. -->
<!-- 指示箭头的图片 -->
<attr name="ptrDrawable" format="reference" />

<!-- Drawable to use as Loading Indicator in the Header View. Overrides value set in ptrDrawable. -->
<!-- 顶部指示箭头的图片，设置后会覆盖ptrDrawable中顶部的设置 -->
<attr name="ptrDrawableStart" format="reference" />

<!-- Drawable to use as Loading Indicator in the Fooer View. Overrides value set in ptrDrawable. -->
<!-- 底部指示箭头的图片，设置后会覆盖ptrDrawable中底部的设置 -->
<attr name="ptrDrawableEnd" format="reference" />

<!-- Whether Android's built-in Over Scroll should be utilised for Pull-to-Refresh. -->
<attr name="ptrOverScroll" format="reference|boolean" />

<!-- Base text color, typeface, size, and style for Header and Footer Loading Views -->
<!-- 设置文字的基本字体 -->
<attr name="ptrHeaderTextAppearance" format="reference" />

<!-- Base text color, typeface, size, and style for Header and Footer Loading Views Sub Header -->
<!-- 设置副标题的基本字体 -->
<attr name="ptrSubHeaderTextAppearance" format="reference" />

<!-- Style of Animation should be used displayed when pulling. -->
<!-- 设置下拉时标识图的动画，默认为rotate -->
<attr name="ptrAnimationStyle">
 <flag name="rotate" value="0x0" />
 <flag name="flip" value="0x1" />
</attr>

<!-- Whether the user can scroll while the View is Refreshing -->
<!-- 设置刷新时是否允许滚动，一般为true -->
<attr name="ptrScrollingWhileRefreshingEnabled" format="reference|boolean" />

<!--
 Whether PullToRefreshListView has it's extras enabled. This allows the user to be
 able to scroll while refreshing, and behaves better. It acheives this by adding
 Header and/or Footer Views to the ListView.
-->
<!-- 允许在listview中添加头/尾视图 -->
<attr name="ptrListViewExtrasEnabled" format="reference|boolean" />

<!--
 Whether the Drawable should be continually rotated as you pull. This only
 takes effect when using the 'Rotate' Animation Style.
-->
<!-- 当设置rotate时，可以用这个来设置刷新时旋转的图片 -->
<attr name="ptrRotateDrawableWhilePulling" format="reference|boolean" />

<!-- BELOW HERE ARE DEPRECEATED. DO NOT USE. -->
<attr name="ptrAdapterViewBackground" format="reference|color" />
<attr name="ptrDrawableTop" format="reference" />
<attr name="ptrDrawableBottom" format="reference" />
</declare-styleable>

</resources>

看到有这么多可以设置的属性，别以为真的就可以定制了。真正要定制还得到layout中改变刷新布局 

3.开始用它建立自己的工程
 设置布局文件
 就是插入PullToRefreshListView

<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="${relativePackage}.${activityClass}"
android:background="#000000">

<!-- The PullToRefreshListView replaces a standard ListView widget. -->

<com.handmark.pulltorefresh.library.PullToRefreshListView
xmlns:ptr="http://schemas.android.com/apk/res-auto"
android:id="@+id/pull_refresh_list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:cacheColorHint="#000000"
android:divider="#19000000"
android:dividerHeight="4dp"
android:fadingEdge="none"
android:fastScrollEnabled="false"
android:footerDividersEnabled="false"
android:headerDividersEnabled="false"
android:smoothScrollbar="true"
ptr:ptrAnimationStyle="rotate"
ptr:ptrHeaderTextColor="#ffffff"
ptr:ptrHeaderSubTextColor="#00ffff"
ptr:ptrHeaderBackground="@null"
ptr:ptrDrawable="@drawable/ic_launcher"/>

</RelativeLayout>

开始编写代码 

1.找到这个控件，并且设置 *  

这里面用到了一个日期的工具类，其实就是设置上次下拉的时间的。此外在下拉后会触发一个异步任务 

/**
* 设置下拉刷新的listview的动作
*/
private void initPTRListView() {
mPullRefreshListView = (PullToRefreshListView) findViewById(R.id.pull_refresh_list);
//设置拉动 *
mPullRefreshListView.setOnRefreshListener(new OnRefreshListener<ListView>() {

@Override
 public void onRefresh(PullToRefreshBase<ListView> refreshView) {
 //设置下拉时显示的日期和时间
 String label = DateUtils.formatDateTime(getApplicationContext(), System.currentTimeMillis(),
  DateUtils.FORMAT_SHOW_TIME | DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_ABBREV_ALL);

// 更新显示的label
 refreshView.getLoadingLayoutProxy().setLastUpdatedLabel(label);
 // 开始执行异步任务，传入适配器来进行数据改变
 new GetDataTask(mPullRefreshListView, mAdapter,mListItems).execute();
 }
});

// 添加滑动到底部的 *
mPullRefreshListView.setOnLastItemVisibleListener(new OnLastItemVisibleListener() {

@Override
 public void onLastItemVisible() {
 Toast.makeText(getApplication(), "已经到底了", Toast.LENGTH_SHORT).show();
 }
});

//mPullRefreshListView.isScrollingWhileRefreshingEnabled();//看刷新时是否允许滑动
//在刷新时允许继续滑动
mPullRefreshListView.setScrollingWhileRefreshingEnabled(true);
//mPullRefreshListView.getMode();//得到模式
//上下都可以刷新的模式。这里有两个选择：Mode.PULL_FROM_START，Mode.BOTH，PULL_FROM_END
mPullRefreshListView.setMode(Mode.BOTH);

/**
 * 设置反馈音效
 */
SoundPullEventListener<ListView> soundListener = new SoundPullEventListener<ListView>(this);
soundListener.addSoundEvent(State.PULL_TO_REFRESH, R.raw.pull_event);
soundListener.addSoundEvent(State.RESET, R.raw.reset_sound);
soundListener.addSoundEvent(State.REFRESHING, R.raw.refreshing_sound);
mPullRefreshListView.setOnPullEventListener(soundListener);
}

2.从上面的那个控件中，得到它包含的listView，并且设置适配器 

//普通的listview对象
private ListView actualListView;
//添加一个链表数组，来存放string数组，这样就可以动态增加string数组中的内容了
private LinkedList<String> mListItems;
//给listview添加一个普通的适配器
private ArrayAdapter<String> mAdapter;

这里用到了一个LinkedList的对象，这个是一个类似于ArrayList的链表数组，比较方便在开头和末尾添加String 

/**
* 设置listview的适配器
*/
private void initListView() {
//通过getRefreshableView()来得到一个listview对象
actualListView = mPullRefreshListView.getRefreshableView();

String []data = new String[] {"android","ios","wp","java","c++","c#"};
mListItems = new LinkedList<String>();
//把string数组中的string添加到链表中
mListItems.addAll(Arrays.asList(data));

mAdapter = new ArrayAdapter<>(getApplicationContext(),
 android.R.layout.simple_list_item_1, mListItems);
actualListView.setAdapter(mAdapter);
}



 

3.写一个异步任务，来模仿从网络加载数据

这里要注意的是，加载完后要出发刷新完成和通知适配器改变的方法

package com.kale.ptrlistviewtest;

import java.util.LinkedList;

import android.os.AsyncTask;
import android.widget.ArrayAdapter;

import com.handmark.pulltorefresh.library.PullToRefreshListView;
import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;

/**
* @author:Jack Tony
* @tips :通过异步任务来加载网络中的数据，进行更新
* @date :2014-10-14
*/
public class GetDataTask extends AsyncTask<Void, Void, Void>{

private PullToRefreshListView mPullRefreshListView;
private ArrayAdapter<String> mAdapter;
private LinkedList<String> mListItems;

public GetDataTask(PullToRefreshListView listView,
 ArrayAdapter<String> adapter,LinkedList<String> listItems) {
// TODO 自动生成的构造函数存根
mPullRefreshListView = listView;
mAdapter = adapter;
mListItems = listItems;
}

@Override
protected Void doInBackground(Void... params) {
//模拟请求
try {
 Thread.sleep(2000);
} catch (InterruptedException e) {
}
return null;
}

@Override
protected void onPostExecute(Void result) {
// TODO 自动生成的方法存根
super.onPostExecute(result);
//得到当前的模式
Mode mode = mPullRefreshListView.getCurrentMode();
if(mode == Mode.PULL_FROM_START) {
 mListItems.addFirst("这是刷新出来的数据");
}
else {
 mListItems.addLast("这是刷新出来的数据");
}
// 通知数据改变了
mAdapter.notifyDataSetChanged();
// 加载完成后停止刷新
mPullRefreshListView.onRefreshComplete();

}

}

贴上acitivty中的全部代码 

MainActivity.java 

package com.kale.ptrlistviewtest;

import java.util.Arrays;
import java.util.LinkedList;

import android.app.Activity;
import android.os.Bundle;
import android.text.format.DateUtils;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnLastItemVisibleListener;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener;
import com.handmark.pulltorefresh.library.PullToRefreshBase.State;
import com.handmark.pulltorefresh.library.PullToRefreshListView;
import com.handmark.pulltorefresh.library.extras.SoundPullEventListener;

public class MainActivity extends Activity {

//一个可以下拉刷新的listView对象
private PullToRefreshListView mPullRefreshListView;
//普通的listview对象
private ListView actualListView;
//添加一个链表数组，来存放string数组，这样就可以动态增加string数组中的内容了
private LinkedList<String> mListItems;
//给listview添加一个普通的适配器
private ArrayAdapter<String> mAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

initView();

//一打开应用就自动刷新，下面语句可以写到刷新按钮里面
mPullRefreshListView.setRefreshing(true);
//new GetDataTask(mPullRefreshListView, mAdapter, mListItems).execute();
//mPullRefreshListView.setRefreshing(false);

}

private void initView() {
initPTRListView();
initListView();
}

/**
* 设置下拉刷新的listview的动作
*/
private void initPTRListView() {
mPullRefreshListView = (PullToRefreshListView) findViewById(R.id.pull_refresh_list);
//设置拉动 *
mPullRefreshListView.setOnRefreshListener(new OnRefreshListener<ListView>() {

@Override
 public void onRefresh(PullToRefreshBase<ListView> refreshView) {
 //设置下拉时显示的日期和时间
 String label = DateUtils.formatDateTime(getApplicationContext(), System.currentTimeMillis(),
  DateUtils.FORMAT_SHOW_TIME | DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_ABBREV_ALL);

// 更新显示的label
 refreshView.getLoadingLayoutProxy().setLastUpdatedLabel(label);
 // 开始执行异步任务，传入适配器来进行数据改变
 new GetDataTask(mPullRefreshListView, mAdapter,mListItems).execute();
 }
});

// 添加滑动到底部的 *
mPullRefreshListView.setOnLastItemVisibleListener(new OnLastItemVisibleListener() {

@Override
 public void onLastItemVisible() {
 Toast.makeText(getApplication(), "已经到底了", Toast.LENGTH_SHORT).show();
 }
});

//mPullRefreshListView.isScrollingWhileRefreshingEnabled();//看刷新时是否允许滑动
//在刷新时允许继续滑动
mPullRefreshListView.setScrollingWhileRefreshingEnabled(true);
//mPullRefreshListView.getMode();//得到模式
//上下都可以刷新的模式。这里有两个选择：Mode.PULL_FROM_START，Mode.BOTH，PULL_FROM_END
mPullRefreshListView.setMode(Mode.BOTH);

/**
 * 设置反馈音效
 */
SoundPullEventListener<ListView> soundListener = new SoundPullEventListener<ListView>(this);
soundListener.addSoundEvent(State.PULL_TO_REFRESH, R.raw.pull_event);
soundListener.addSoundEvent(State.RESET, R.raw.reset_sound);
soundListener.addSoundEvent(State.REFRESHING, R.raw.refreshing_sound);
mPullRefreshListView.setOnPullEventListener(soundListener);
}

/**
* 设置listview的适配器
*/
private void initListView() {
//通过getRefreshableView()来得到一个listview对象
actualListView = mPullRefreshListView.getRefreshableView();

String []data = new String[] {"android","ios","wp","java","c++","c#"};
mListItems = new LinkedList<String>();
//把string数组中的string添加到链表中
mListItems.addAll(Arrays.asList(data));

mAdapter = new ArrayAdapter<>(getApplicationContext(),
 android.R.layout.simple_list_item_1, mListItems);
actualListView.setAdapter(mAdapter);
}
}

源码下载：http://xiazai.jb51.net/201609/yuanma/AndroidListView(jb51.net).rar