ListView下拉刷新效果-优快云博客

本文介绍了一种简洁实现ListView下拉刷新效果的方法。通过自定义CustomListView组件，结合简单的触摸事件处理，实现了平滑的刷新动画及回调通知。代码示例展示了如何集成此组件到应用程序中。

ListView下拉刷新效果

网上关于这个方面的文章已经很多了，为什么我还要发表这篇文章呢？原因很简单，我觉得可以可以用更加简洁的方法实现。话不多说，上代码。

CustomListView.java

package com.markslin.listviewtest;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.ProgressBar;

/**
 * Created by MarksLin on 2015/5/7 0007.
 */
public class CustomListView extends ListView {
    private int startY;
    private boolean firstMeasured = true;
    private View header;
    private ProgressBar headerProgressBar;
    private ImageView headerProgressImg;
    private int headerHeight;

    private OnRefreshListener listener;
    public interface OnRefreshListener {
        void onRefresh();
    }
    /**
     * 接口回调，通知主程序加载数据
     * @param listener
     */
    public void setOnRefreshListener(OnRefreshListener listener){
        this.listener=listener;
    }
    public CustomListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        header = View.inflate(getContext(), R.layout.listview_header, null);
        headerProgressBar = (ProgressBar) header.findViewById(R.id.header_progressBar);
        headerProgressImg = (ImageView) header.findViewById(R.id.header_progressImg);
        addHeaderView(header);
    }


    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);
        if (firstMeasured) {//onLayout方法会被调用多次,因此要处理一下
            firstMeasured = false;
            intiView();
        }
    }

    /**
     * 初始化ListView的顶部布局
     */
    private void intiView() {
        headerHeight = header.getMeasuredHeight();
        setHeaderTopPadding(-headerHeight);
    }

    /**
     * 设置Header距顶部的padding
     * @param padding
     */
    private void setHeaderTopPadding(int padding) {
        header.setPadding(header.getPaddingLeft(), padding, header.getPaddingRight(), header.getPaddingBottom());
    }

    /**
     * 用与程序数据加载完毕后调用
     */
    public void loadFinish() {
        setHeaderTopPadding(-headerHeight);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                if (getFirstVisiblePosition() == 0) {
                    startY = (int) event.getY();
                  headerProgressImg.setVisibility(VISIBLE);
                    headerProgressBar.setVisibility(GONE);
                }
                break;
            case MotionEvent.ACTION_MOVE:
                int slideHeight = (int) event.getY() - startY;

                if (slideHeight < 3 * headerHeight && slideHeight > headerHeight)
                    setHeaderTopPadding(-headerHeight + (int) event.getY() - startY);

                headerProgressImg.setRotation(120 * ((int) event.getY() - startY) / headerHeight);
                break;
            case MotionEvent.ACTION_UP:
                if (((int) event.getY() - startY) > headerHeight) {
                    headerProgressImg.setVisibility(GONE);
                    headerProgressBar.setVisibility(VISIBLE);
                    setHeaderTopPadding(0);
                    listener.onRefresh();
                } else
                    setHeaderTopPadding(-header.getMeasuredHeight());
            default:
                break;
        }
        return super.onTouchEvent(event);
    }

}

activity_main.xml

<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=".MainActivity">

    <com.markslin.listviewtest.CustomListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listView"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

listview_header.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <ProgressBar
        android:layout_width="72dp"
        android:layout_height="72dp"
        android:id="@+id/header_progressBar"
        android:padding="@dimen/activity_horizontal_margin"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true"
        android:indeterminateDrawable="@drawable/loading"
        android:visibility="gone"/>
    <ImageView
        android:layout_width="72dp"
        android:layout_height="72dp"
        android:id="@+id/header_progressImg"
        android:padding="@dimen/activity_horizontal_margin"
        android:src="@drawable/loading_img"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true" />
</RelativeLayout>

MainActivity.java

package com.markslin.listviewtest;

import android.app.Activity;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;


public class MainActivity extends Activity implements CustomListView.OnRefreshListener{
    private CustomListView listView;
    private List<String> strings=new ArrayList<>();
    private ListViewAdapter adapter;
    private Handler handler;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView= (CustomListView) findViewById(R.id.listView);

        for (int i=0;i<30;i++)
            strings.add("Hello");

        adapter=new ListViewAdapter(strings);

        listView.setAdapter(adapter);
        listView.setOnRefreshListener(this);

        handler=new Handler(){
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if (msg.what==1)
                    listView.loadFinish();
            }
        };

    }

    @Override
    public void onRefresh() {
        handler.sendEmptyMessageDelayed(1,3000);
    }
}

ListViewAdapter.java

package com.markslin.listviewtest;

import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by MarksLin on 2015/5/7 0007.
 */
public class ListViewAdapter extends BaseAdapter{
    private List<String> strings=new ArrayList<>();

    public ListViewAdapter(List<String> strings) {
        this.strings = strings;
    }

    @Override
    public int getCount() {
        return strings.size();
    }

    @Override
    public Object getItem(int position) {
        return strings.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        TextView view=new TextView(parent.getContext());
        view.setHeight(75);
        view.setText(strings.get(position));
        return view;
    }
}