开源项目PullToRefresh详解（一）——PullToRefreshListView

  

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，并且设置监听器

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);
        //设置拉动监听器
        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();
            }
        });

        // 添加滑动到底部的监听器
        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);
        //设置拉动监听器
        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();
            }
        });

        // 添加滑动到底部的监听器
        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://download.csdn.net/detail/shark0017/8035465