Android自定义下拉刷新

网上的下拉刷新功能很多，不过基本上都是隐藏header的，而项目里面需要只隐藏部分的header，类似QQ好友动态的效果，修改了一些现有的，最后有很多问题，所以就自己自定义了一个，逻辑也很简单，首先就是重写ListView,然后覆写onTouchEvent，然后根据手的触摸位置计算差值，然后移动header.下面是效果图：

主要的部分就是下拉刷新组件，代码如下，里面我都要注释：

package com.jwzhangjie.mypullrefresh;

import android.content.Context;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class PullReFreshLibrary extends ListView{
	//下拉的父布局
	private LinearLayout conterViewLayout;
	//实现下拉的头部
	private RelativeLayout headerView;
	//提示下拉状态
	private TextView pullTextView;
	private LayoutInflater mInflater;
	//下拉框的高度
	private int headviewHeight;
	//下拉框距离顶部的初始高度
	private int initHeight;
	//手按下去的y轴坐标
	private int initPosition = 0;
	//最新的手的y轴坐标
	private int lastPositon =0;
	//下拉移动的最小距离
	private int minMarge = 5;
	//当前下拉head的距离顶部的高度
	private int currentHeight = -100;
	//下拉head的各种状态
	private static enum State{
        PULL_TO_REFRESH,
        RELEASE_TO_REFRESH,
        REFRESHING,
        REFRESHCOMPLETE,
    }
	private State state = State.PULL_TO_REFRESH;

	public PullReFreshLibrary(Context context, AttributeSet attrs) {
		super(context, attrs);
		mInflater = LayoutInflater.from(context);
		conterViewLayout = (LinearLayout) mInflater.inflate(R.layout.headview, null);
		headerView = (RelativeLayout)conterViewLayout.findViewById(R.id.testHeader);
		pullTextView = (TextView)headerView.findViewById(R.id.pullTextView);
		headviewHeight = (int)context.getResources().getDimensionPixelSize(R.dimen.header_view_height);
		initHeight = (int)context.getResources().getDimensionPixelSize(R.dimen.init_height);
		addHeaderView(conterViewLayout);
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		if (state == State.REFRESHING) {
			return true;
		}
		switch (ev.getAction()) {
		case MotionEvent.ACTION_DOWN:
			initPosition = (int)ev.getY();
			break;
		case MotionEvent.ACTION_MOVE:
			if (getFirstVisiblePosition() == 0) {
				lastPositon = (int)ev.getY();
				int diff = lastPositon - initPosition;
				if (Math.abs(diff) > minMarge) {
					diff = (int)(diff / 2.7);
				}
				initPosition = lastPositon;
				int newHeaderPadding = Math.max(Math.round(currentHeight + diff),  -headviewHeight);
				if (state != State.REFRESHING && newHeaderPadding != currentHeight) {
					if (newHeaderPadding > 0) {
						currentHeight = 0;
					}else {
						currentHeight = newHeaderPadding;
					}
					margeTop();
				}
			}
			break;
		case MotionEvent.ACTION_UP:
			if (state == State.RELEASE_TO_REFRESH) {
				setState(State.RELEASE_TO_REFRESH);
			}else if (getFirstVisiblePosition() == 0 && currentHeight > -initHeight) {
				resetHeader();
			}
			break;
		}
		return super.onTouchEvent(ev);
	}

	/**
	 * 设置下拉head的状态以及处理功能
	 * @param state
	 */
	private void setState(State state){
		this.state = state;
		switch (state) {
		case PULL_TO_REFRESH:
			pullTextView.setVisibility(View.VISIBLE);
			pullTextView.setText("下拉刷新");
			break;
		case RELEASE_TO_REFRESH:
			if (onRefreshListener == null) {
				state = State.PULL_TO_REFRESH;
				resetHeader();
			}else {
				state = State.REFRESHING;
				pullTextView.setVisibility(View.VISIBLE);
				pullTextView.setText("刷新中...");
				onRefreshListener.onRefresh();
			}
			break;
		case REFRESHCOMPLETE:
			state = State.PULL_TO_REFRESH;
			pullTextView.setText("下拉刷新");
			resetHeader();
			break;
		}
	}
	/**
	 * 设置下拉head距离顶部的高度
	 */
	private void margeTop(){
		MarginLayoutParams mlp = (ViewGroup.MarginLayoutParams) headerView.getLayoutParams();
		mlp.topMargin = currentHeight;
        headerView.setLayoutParams(mlp);
        if (currentHeight > -10 && state != State.RELEASE_TO_REFRESH) {
        	state = State.RELEASE_TO_REFRESH;
        	pullTextView.setText("松手刷新");
		}else if (currentHeight < -10 && state != State.PULL_TO_REFRESH) {
			state = State.PULL_TO_REFRESH;
			pullTextView.setText("下拉刷新");
		}
	}
	/**
	 * 初始化下拉head的高度
	 */
	private void resetHeader(){
		MarginLayoutParams mlp = (ViewGroup.MarginLayoutParams) headerView.getLayoutParams();
		mlp.topMargin = -initHeight;
		currentHeight = -initHeight;
		headerView.setLayoutParams(mlp);
	}
	/**
	 * 实现刷新过程的回调接口
	 */
	private OnRefreshListener onRefreshListener;

	public void setOnRefreshListener(OnRefreshListener onRefreshListener){
		this.onRefreshListener = onRefreshListener;
	}
	public interface OnRefreshListener{
        public void onRefresh();
    }
	/**
	 * 刷新完成调用
	 */
	 public void onRefreshComplete(){
		 setState(State.REFRESHCOMPLETE);
	}

}

适配器adater,这个很简陋，主要是辅助测试

package com.jwzhangjie.mypullrefresh;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MyAdapter extends BaseAdapter{

	private LayoutInflater mInflater;
	public MyAdapter(Context context){
		mInflater = LayoutInflater.from(context);
	}
	@Override
	public int getCount() {
		return 19;
	}

	@Override
	public Object getItem(int position) {
		return null;
	}

	@Override
	public long getItemId(int position) {
		return 0;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		TextView textView;
		if (convertView == null) {
			convertView = mInflater.inflate(R.layout.item_listview, null);
			textView = (TextView)convertView.findViewById(R.id.item_test);
			convertView.setTag(textView);
		}else {
			textView = (TextView)convertView.getTag();
		}
		textView.setText("测试数据："+position);
		return convertView;
	}

}

然后就是Activity的调用：

package com.jwzhangjie.mypullrefresh;

import com.jwzhangjie.mypullrefresh.PullReFreshLibrary.OnRefreshListener;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.annotation.SuppressLint;
import android.app.Activity;

public class MainActivity extends Activity {

	private MyAdapter myAdapter;
	private PullReFreshLibrary listView;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		myAdapter = new MyAdapter(this);
		listView = (PullReFreshLibrary)findViewById(R.id.testpull);
		listView.setAdapter(myAdapter);
		listView.setOnRefreshListener(new OnRefreshListener() {
			@Override
			public void onRefresh() {
				handler.sendEmptyMessageDelayed(1, 4000);
			}
		});
	}
	@SuppressLint("HandlerLeak")
	public Handler handler = new Handler(){
		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);
			listView.onRefreshComplete();
		}

	};
}

我里面的布局也都很简单，

activity_main.xml

<LinearLayout 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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

   <com.jwzhangjie.mypullrefresh.PullReFreshLibrary
       android:id="@+id/testpull"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       ></com.jwzhangjie.mypullrefresh.PullReFreshLibrary>

</LinearLayout>

headview.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    >
	<RelativeLayout
	    android:id="@+id/testHeader"
	    android:layout_width="match_parent"
	        android:layout_height="300dip"
	        android:layout_marginTop="-48dip"
	         android:background="@drawable/main_photo2"
	         >
		<LinearLayout
            android:id="@+id/ptr_id_textwrapper"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_marginTop="10dip"
            android:background="@drawable/refresh_text_bg"
            >
            <TextView
                android:id="@+id/pullTextView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:paddingLeft="20dip"
                android:paddingRight="20dip"
                android:paddingTop="5dip"
                android:paddingBottom="5dip"
                android:textSize="12sp"
                android:textColor="#FFFFFFFF"
                android:layout_gravity="center"
                  android:text="测试刷新"
                 />
        </LinearLayout>
	</RelativeLayout>
    </LinearLayout>

item_listview.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

	<TextView
	    android:id="@+id/item_test"
	    android:layout_width="match_parent"
	    android:layout_height="40dip"
	    />
</LinearLayout>

 <dimen name="init_height">48dip</dimen>
 <dimen name="header_view_height">300dip</dimen>