Android Studio—PullToRefresh 框架

1 概念

Android Studio-PullToRefresh框架是一个实现View下拉刷新的开源框架。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。

2 源码分析

开源下载地址：https://github.com/chrisbanes/Android-PullToRefresh

下载项目包，将library包导入，查看源码。

<?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 -->
            <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. -->
        <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>

之后到layout中改变刷新布局

3 使用

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>

Activity 中设置下拉刷新监听

1.使用 setOnRefreshListener设置刷新监听,
2.使用OnRefreshListener回调在 onRefresh方法中触发加载数据操作.实现下拉监听.
3.使用 AsyncTask 实现加载数据 .

public class MainActivity extends AppCompatActivity {
    PullToRefreshListView id_lv_test;

    private List<String> mList = new ArrayList<String>(){
        {
            add("Chinese");
            add("Math");
            add("English");
        }
    };
    private ArrayAdapter<String> mLvAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 获取控件
        id_lv_test = (PullToRefreshListView) findViewById(R.id.id_lv_test);
        // 设置适配器
        mLvAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,mList);
        id_lv_test.setAdapter(mLvAdapter);
        // 设置下拉刷新监听.
        id_lv_test.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener<ListView>() {
            @Override
            public void onRefresh(PullToRefreshBase<ListView> refreshView) {
                new AsyncTask<Void,Void,Void>(){
                    @Override
                    protected Void doInBackground(Void... params) {
                        SystemClock.sleep(3 * 1000);
                        mList.add("新数据 - " + mLvAdapter.getCount());
                        return null;
                    }
                    @Override
                    protected void onPostExecute(Void aVoid) {
                        id_lv_test.onRefreshComplete();
                    }
                }.execute();

            }
        }
        );

    }
}

id_lv_test.setMode(PullToRefreshBase.Mode.BOTH);
// 设置上下刷新
id_lv_test.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2<ListView>() {
    @Override
    public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {

        Log.d(TAG,"下拉动作 : " + Thread.currentThread().getId());

        id_lv_test.postDelayed(new Runnable() {
            @Override
            public void run() {
                id_lv_test.onRefreshComplete();
            }
        },50);

    }

    @Override
    public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
        Log.d(TAG,"上拉动作");
        id_lv_test.postDelayed(new Runnable() {
            @Override
            public void run() {
                id_lv_test.onRefreshComplete();
            }
        },50);
    }
});
id_lv_test.getLoadingLayoutProxy(false,true).setPullLabel("上拉加载更多.");
id_lv_test.getLoadingLayoutProxy(false,true).setRefreshingLabel("正在加载数据...");
id_lv_test.getLoadingLayoutProxy(false,true).setReleaseLabel("松开加载更多...");

id_lv_test.getLoadingLayoutProxy(true, false).setPullLabel("下拉刷新...");
id_lv_test.getLoadingLayoutProxy(true, false).setRefreshingLabel("正在刷新...");
id_lv_test.getLoadingLayoutProxy(true,false).setReleaseLabel("松开刷新...");