谷歌官方的下拉刷新控件SwipeRefreshLayout

众所周知，谷歌有一个自己的下拉刷新控件，没错！我说的就是v4包下的SwipeRefreshLayout，美中不足的是没有上拉加载更多的功能，这一点比较遗憾，有点蛋蛋的忧伤~~but！！！，网上已经有很多大神把他的功能重写了，实现了上拉加载更多的功能，利用了下午的时间学习了一下

先看一下大神是如何把他重写的，从重写的方法来看，里面嵌套的只能是ListView，俗话说的好：不要重复造轮子，咱也站在巨人的肩膀上学习一下：

package com.example.lenovo.pulltorefresh;

import android.content.Context;
import android.support.v4.widget.SwipeRefreshLayout;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.widget.AbsListView;
import android.widget.ListView;

public class MySwipeRefreshLayout extends SwipeRefreshLayout implements AbsListView.OnScrollListener {

    /** * 滑动到最下面时的上拉操作 */

    private int mTouchSlop;
    /** * listview实例 */
    private ListView mListView;

    /** * 上拉监听器, 到了最底部的上拉加载操作 */
    private OnLoadListener mOnLoadListener;

    /** * ListView的加载中footer */
    private View mListViewFooter;

    /** * 按下时的y坐标 */
    private int mYDown;
    /** * 抬起时的y坐标, 与mYDown一起用于滑动到底部时判断是上拉还是下拉 */
    private int mLastY;
    /** * 是否在加载中 ( 上拉加载更多 ) */
    private boolean isLoading = false;
    public MySwipeRefreshLayout(Context context) {
        this(context, null);
    }

    public MySwipeRefreshLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
        mListViewFooter = LayoutInflater.from(context).inflate(R.layout.listview_footer, null,false);
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        if (mListView == null) {
            getListView();
        }
    }

    /** * 获取ListView对象 */
    private void getListView() {
        int childs = getChildCount();
        if (childs > 0) {
            View childView = getChildAt(0);
            if (childView instanceof ListView) {
                mListView = (ListView) childView;
                // 设置滚动监听器给ListView, 使得滚动的情况下也可以自动加载
                mListView.setOnScrollListener(this);
                Log.d(VIEW_LOG_TAG, "### 找到listview");
            }
        }
    }

    /** * 事件分发的处理 */
    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        final int action = event.getAction();
        switch (action) {
            case MotionEvent.ACTION_DOWN:
                mYDown = (int) event.getRawY();
                break;
            case MotionEvent.ACTION_MOVE:
                mLastY = (int) event.getRawY();
                break;
            case MotionEvent.ACTION_UP:
                if (canLoad()) {
                    loadData();
                }
                break;
            default:
                break;
        }
        return super.dispatchTouchEvent(event);
    }

    /** * 是否可以加载更多, 条件是到了最底部, listview不在加载中, 且为上拉操作. */
    private boolean canLoad() {
        return isBottom() && !isLoading && isPullUp();
    }

    /** * 判断是否到了最底部 */
    private boolean isBottom() {

        if (mListView != null && mListView.getAdapter() != null) {
            return mListView.getLastVisiblePosition() == (mListView.getAdapter().getCount() - 1);
        }
        return false;
    }

    /** * 是否是上拉操作 */
    private boolean isPullUp() {
        return (mYDown - mLastY) >= mTouchSlop;
    }

    /** * 如果到了最底部,而且是上拉操作.那么执行onLoad方法 */
    private void loadData() {
        if (mOnLoadListener != null) {
            setLoading(true);
            mOnLoadListener.onLoad();
        }
    }

    /** * 加载回调 */
    public void setLoading(boolean loading) {
        isLoading = loading;
        if (isLoading) {
            mListView.addFooterView(mListViewFooter);
        } else {
            mListView.removeFooterView(mListViewFooter);
            mYDown = 0;
            mLastY = 0;
        }
    }

    /** * 加载监听 */
    public void setOnLoadListener(OnLoadListener loadListener) {
        mOnLoadListener = loadListener;
    }

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {

    }

    /** * 滚动到最底部也执行加载更多 */
    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
                         int totalItemCount) {
        if (canLoad()) {
            loadData();
        }
    }

    /** * 加载更多的监听 */
    public static interface OnLoadListener {
        public void onLoad();
    }
}

注释很详细，就不说明了~~

MainActivity代码：

package com.example.lenovo.pulltorefresh;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.widget.SwipeRefreshLayout;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;

public class MainActivity extends Activity {
    private ListView listView;
    private MySwipeRefreshLayout mySwipeRefreshLayout;
    private ArrayList<String> listData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        initData();
        listView.setAdapter(new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, listData));
        //下拉刷新监听
        mySwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {

            @Override
            public void onRefresh() {
                new Handler().postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        //刷新结束后调用一下该方法
                        mySwipeRefreshLayout.setRefreshing(false);
                    }
                }, 3000);
            }
        });
        //上拉加载更多监听
        mySwipeRefreshLayout.setOnLoadListener(new MySwipeRefreshLayout.OnLoadListener() {

            @Override
            public void onLoad() {
                new Handler().postDelayed(new Runnable() {

                    @Override
                    public void run() {
                        // 加载完后调用该方法
                        mySwipeRefreshLayout.setLoading(false);
                    }
                }, 3000);
            }
        });
    }

    private void initData() {
        listData = new ArrayList<>();
        for(int i=0;i<30;i++){
            listData.add("数据"+i);
        }
    }

    private void initView() {
        mySwipeRefreshLayout = (MySwipeRefreshLayout)findViewById(R.id.swipe_layout);
        //设置旋转箭头的颜色
        mySwipeRefreshLayout.setColorSchemeColors(Color.BLUE);
        listView = (ListView) findViewById(R.id.listview);
    }
}

Over！！就是这么生猛！！效果图就不上了~