Android ListView下拉刷新，最基本代码

网上找到些例子，功能都实现的很好，各种刷新，功能多，也就意味着代码多，想定制自己的下拉刷新，无从下手。

自己写了个用于下拉刷新的最简单的例子，简单到只有下拉的界面变化，什么时候刷新，什么时候该处理什么，请自己动手。

此代码就像写程序的“Hello Word”，带你入门，弄懂基本原理，高深的部分，网上已经有人做的很好了，推荐个各种刷新的源码：android-pulltorefresh-master。

注：以下代码不需要layout文件，由代码布局，由代码生成ListView所需数据，尽量简化，希望能帮到读者。

package com.kevinshq.pulltorefresh;import android.app.Activity;import android.graphics.Color;import android.graphics.Typeface;import android.os.Bundle;import android.view.Gravity;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.LinearLayout;import android.widget.ListAdapter;import android.widget.ListView;import android.widget.TextView;public class PullToRefreshActivity extends Activity {public static final String TAG = "PullToRefreshActivity";private final static int RATIO = 2;private boolean isRecored;private int firstItemIndex = 0;private float startY = 0;private TextView headTextView = null;private ListView listView = null;private View.OnTouchListener onTouchListener = new View.OnTouchListener() {@Overridepublic boolean onTouch(View v, MotionEvent event) {// TODO Auto-generated method stubfloat tempY = event.getY();firstItemIndex = listView.getFirstVisiblePosition();switch (event.getAction()) {case MotionEvent.ACTION_DOWN:case MotionEvent.ACTION_MOVE:if (!isRecored && (firstItemIndex == 0)) {isRecored = true;startY = tempY;}break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_CANCEL:isRecored = false;break;default:break;}switch (event.getAction()) {case MotionEvent.ACTION_DOWN:break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_CANCEL:if (tempY > startY) {listView.setPadding(0, -200, 0, 0);}break;case MotionEvent.ACTION_MOVE:if (isRecored && tempY > startY) {listView.setPadding(0, (int) ((tempY-startY)/RATIO-200), 0, 0);}break;default:break;}return false;}};private ListAdapter adapter = new BaseAdapter() {@Overridepublic View getView(int position, View convertView, ViewGroup parent) {// TODO Auto-generated method stubTextView tv = (TextView) convertView;if (tv == null) {tv = new TextView(getApplicationContext());}tv.setGravity(Gravity.CENTER);tv.setMinHeight(50);tv.setText(String.valueOf(position));tv.setBackgroundColor(Color.GRAY);return tv;}@Overridepublic long getItemId(int position) {// TODO Auto-generated method stubreturn 0;}@Overridepublic Object getItem(int position) {// TODO Auto-generated method stubreturn position;}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn 50;}};@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);ViewGroup.LayoutParams lp_ViewGroup = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.MATCH_PARENT);LinearLayout linearLayout = new LinearLayout(this);linearLayout.setOrientation(LinearLayout.VERTICAL);setContentView(linearLayout, lp_ViewGroup);headTextView = new TextView(this);headTextView.setGravity(Gravity.CENTER);headTextView.setMinHeight(200);headTextView.setText("Head");headTextView.setTypeface(Typeface.DEFAULT_BOLD);headTextView.setTextSize(50);headTextView.setBackgroundColor(Color.GREEN);headTextView.invalidate();LinearLayout.LayoutParams lp_LinearLayout = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.MATCH_PARENT);listView = new ListView(this);listView.addHeaderView(headTextView, null, false);listView.setOnTouchListener(onTouchListener);listView.setAdapter(adapter);listView.setPadding(0, -200, 0, 0);linearLayout.addView(listView, lp_LinearLayout);}}