Android新浪微博下拉刷新(最新消息显示在最上面)

查看最新消息要用到类似新浪微博下拉刷新 功能！把最新的消息显示在最上面！
代码如下：
pulltorefreshlistview类代码

package com.markupartist.android.widget;

import java.util.date;
import com.markupartist.android.example.pulltorefresh.r;
import android.content.context;
import android.util.attributeset;
import android.util.log;
import android.view.layoutinflater;
import android.view.motionevent;
import android.view.view;
import android.view.viewgroup;
import android.view.animation.linearinterpolator;
import android.view.animation.rotateanimation;
import android.widget.abslistview;
import android.widget.abslistview.onscrolllistener;
import android.widget.baseadapter;
import android.widget.imageview;
import android.widget.linearlayout;
import android.widget.listview;
import android.widget.progressbar;
import android.widget.textview;

public class pulltorefreshlistview extends listview implements onscrolllistener {
private static final string tag = "listview";
private final static int release_to_refresh = 0;
private final static int pull_to_refresh = 1;
private final static int refreshing = 2;
private final static int done = 3;
private final static int loading = 4;
// 实际的padding的距离与界面上偏移距离的比例
private final static int ratio = 3;
private layoutinflater inflater;
private linearlayout headview;
private textview tipstextview;
private textview lastupdatedtextview;
private imageview arrowimageview;
private progressbar progressbar;

private rotateanimation animation;
private rotateanimation reverseanimation;
// 用于保证starty的值在一个完整的touch事件中只被记录一次
private boolean isrecored;
private int headcontentwidth;
private int headcontentheight;
private int starty;
private int firstitemindex;
private int state;
private boolean isback;
private onrefreshlistener refreshlistener;
private boolean isrefreshable;
public pulltorefreshlistview(context context) {
super(context);
init(context);
}
public pulltorefreshlistview(context context, attributeset attrs) {
super(context, attrs);
init(context);
}
private void init(context context) {
setcachecolorhint(context.getresources().getcolor(android.r.color.transparent));
inflater = layoutinflater.from(context);
headview = (linearlayout) inflater.inflate(r.layout.pull_to_refresh_header, null);
arrowimageview = (imageview) headview
.findviewbyid(r.id.head_arrowimageview);
arrowimageview.setminimumwidth(70);
arrowimageview.setminimumheight(50);
progressbar = (progressbar) headview
.findviewbyid(r.id.head_progressbar);
tipstextview = (textview) headview.findviewbyid(r.id.head_tipstextview);
lastupdatedtextview = (textview) headview
.findviewbyid(r.id.head_lastupdatedtextview);
measureview(headview);
headcontentheight = headview.getmeasuredheight();
headcontentwidth = headview.getmeasuredwidth();
headview.setpadding(0, -1 * headcontentheight, 0, 0);
headview.invalidate();
log.v("size", "width:" + headcontentwidth + " height:"
+ headcontentheight);
addheaderview(headview, null, false);
setonscrolllistener(this);
animation = new rotateanimation(0, -180,
rotateanimation.relative_to_self, 0.5f,
rotateanimation.relative_to_self, 0.5f);
animation.setinterpolator(new linearinterpolator());
animation.setduration(250);
animation.setfillafter(true);
reverseanimation = new rotateanimation(-180, 0,
rotateanimation.relative_to_self, 0.5f,
rotateanimation.relative_to_self, 0.5f);
reverseanimation.setinterpolator(new linearinterpolator());
reverseanimation.setduration(200);
reverseanimation.setfillafter(true);
state = done;
isrefreshable = false;
}
public void onscroll(abslistview arg0, int firstvisiableitem, int arg2,
int arg3) {
firstitemindex = firstvisiableitem;
}
public void onscrollstatechanged(abslistview arg0, int arg1) {
}
public boolean ontouchevent(motionevent event) {

firstitemindex=getfirstvisibleposition();
if (isrefreshable) {
switch (event.getaction()) {
case motionevent.action_down:
if (firstitemindex == 0 && !isrecored) {
isrecored = true;
starty = (int) event.gety();
log.v(tag, "在down时候记录当前位置‘");
}
break;
case motionevent.action_up:
if (state != refreshing && state != loading) {
if (state == done) {
// 什么都不做
}
if (state == pull_to_refresh) {
state = done;
changeheaderviewbystate();
log.v(tag, "由下拉刷新状态，到done状态");
}
if (state == release_to_refresh) {
state = refreshing;
changeheaderviewbystate();
onrefresh();
log.v(tag, "由松开刷新状态，到done状态");
}
}
isrecored = false;
isback = false;
break;
case motionevent.action_move:
int tempy = (int) event.gety();
if (!isrecored && firstitemindex == 0) {
log.v(tag, "在move时候记录下位置");
isrecored = true;
starty = tempy;
}
if (state != refreshing && isrecored && state != loading) {
// 保证在设置padding的过程中，当前的位置一直是在head，否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动
// 可以松手去刷新了
if (state == release_to_refresh) {
setselection(0);
// 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步
if (((tempy - starty) / ratio < headcontentheight)
&& (tempy - starty) > 0) {
state = pull_to_refresh;
changeheaderviewbystate();
log.v(tag, "由松开刷新状态转变到下拉刷新状态");
}
// 一下子推到顶了
else if (tempy - starty <= 0) {
state = done;
changeheaderviewbystate();
log.v(tag, "由松开刷新状态转变到done状态");
}
// 往下拉了，或者还没有上推到屏幕顶部掩盖head的地步
else {
// 不用进行特别的操作，只用更新paddingtop的值就行了
}
}
// 还没有到达显示松开刷新的时候,done或者是pull_to_refresh状态
if (state == pull_to_refresh) {
setselection(0);
// 下拉到可以进入release_to_refresh的状态
if ((tempy - starty) / ratio >= headcontentheight) {
state = release_to_refresh;
isback = true;
changeheaderviewbystate();
log.v(tag, "由done或者下拉刷新状态转变到松开刷新");
}
// 上推到顶了
else if (tempy - starty <= 0) {
state = done;
changeheaderviewbystate();
log.v(tag, "由done或者下拉刷新状态转变到done状态");
}
}
// done状态下
if (state == done) {
if (tempy - starty > 0) {
state = pull_to_refresh;
changeheaderviewbystate();
}
}
// 更新headview的size
if (state == pull_to_refresh) {
headview.setpadding(0, -1 * headcontentheight
+ (tempy - starty) / ratio, 0, 0);
}
// 更新headview的paddingtop
if (state == release_to_refresh) {
headview.setpadding(0, (tempy - starty) / ratio
- headcontentheight, 0, 0);
}
}
break;
}
}
return super.ontouchevent(event);
}
// 当状态改变时候，调用该方法，以更新界面
private void changeheaderviewbystate() {
switch (state) {
case release_to_refresh:
arrowimageview.setvisibility(view.visible);
progressbar.setvisibility(view.gone);
tipstextview.setvisibility(view.visible);
lastupdatedtextview.setvisibility(view.visible);
arrowimageview.clearanimation();
arrowimageview.startanimation(animation);
tipstextview.settext("松开刷新");
log.v(tag, "当前状态，松开刷新");
break;
case pull_to_refresh:
progressbar.setvisibility(view.gone);
tipstextview.setvisibility(view.visible);
lastupdatedtextview.setvisibility(view.visible);
arrowimageview.clearanimation();
arrowimageview.setvisibility(view.visible);
// 是由release_to_refresh状态转变来的
if (isback) {
isback = false;
arrowimageview.clearanimation();
arrowimageview.startanimation(reverseanimation);
tipstextview.settext("下拉刷新");
} else {
tipstextview.settext("下拉刷新");
}
log.v(tag, "当前状态，下拉刷新");
break;
case refreshing:
headview.setpadding(0, 0, 0, 0);
progressbar.setvisibility(view.visible);
arrowimageview.clearanimation();
arrowimageview.setvisibility(view.gone);
tipstextview.settext("正在刷新...");
lastupdatedtextview.setvisibility(view.visible);
log.v(tag, "当前状态,正在刷新...");
break;
case done:
headview.setpadding(0, -1 * headcontentheight, 0, 0);
progressbar.setvisibility(view.gone);
arrowimageview.clearanimation();
arrowimageview.setimageresource(r.drawable.ic_pulltorefresh_arrow);
tipstextview.settext("下拉刷新");
lastupdatedtextview.setvisibility(view.visible);
log.v(tag, "当前状态，done");
break;
}
}
public void setonrefreshlistener(onrefreshlistener refreshlistener) {
this.refreshlistener = refreshlistener;
isrefreshable = true;
}
public interface onrefreshlistener {
public void onrefresh();
}
public void onrefreshcomplete() {
state = done;
lastupdatedtextview.settext("最近更新:" + new date().tolocalestring());
changeheaderviewbystate();
}
private void onrefresh() {
if (refreshlistener != null) {
refreshlistener.onrefresh();
}
}
// 此方法直接照搬自网络上的一个下拉刷新的demo，此处是“估计”headview的width以及height
private void measureview(view child) {
viewgroup.layoutparams p = child.getlayoutparams();
if (p == null) {
p = new viewgroup.layoutparams(viewgroup.layoutparams.fill_parent,
viewgroup.layoutparams.wrap_content);
}
int childwidthspec = viewgroup.getchildmeasurespec(0, 0 + 0, p.width);
int lpheight = p.height;
int childheightspec;
if (lpheight > 0) {
childheightspec = measurespec.makemeasurespec(lpheight,
measurespec.exactly);
} else {
childheightspec = measurespec.makemeasurespec(0,
measurespec.unspecified);
}
child.measure(childwidthspec, childheightspec);
}
public void setadapter(baseadapter adapter) {
lastupdatedtextview.settext("最近更新:" + new date().tolocalestring());
super.setadapter(adapter);
}
}

activity调用代码

package com.markupartist.android.example.pulltorefresh;
import java.util.arrays;
import java.util.linkedlist;
import android.app.listactivity;
import android.os.asynctask;
import android.os.bundle;
import android.widget.arrayadapter;
import com.markupartist.android.widget.pulltorefreshlistview;
import com.markupartist.android.widget.pulltorefreshlistview.onrefreshlistener;
public class pulltorefreshactivity extends listactivity {
private linkedlist<string> mlistitems;
/** called when the activity is first created. */
@override
public void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.pull_to_refresh);
// set a listener to be invoked when the list should be refreshed.
((pulltorefreshlistview) getlistview()).setonrefreshlistener(new onrefreshlistener() {
@override
public void onrefresh() {
// do work to refresh the list here.
new getdatatask().execute();
}
});
mlistitems = new linkedlist<string>();
mlistitems.addall(arrays.aslist(mstrings));
arrayadapter<string> adapter = new arrayadapter<string>(this,
android.r.layout.simple_list_item_1, mlistitems);
setlistadapter(adapter);
}
private class getdatatask extends asynctask<void, void, string[]> {
@override
protected string[] doinbackground(void... params) {
// simulates a background job.
try {
thread.sleep(2000);
} catch (interruptedexception e) {

}
return mstrings;
}
@override
protected void onpostexecute(string[] result) {
mlistitems.addfirst("added after refresh...");
// call onrefreshcomplete when the list has been refreshed.
((pulltorefreshlistview) getlistview()).onrefreshcomplete();
super.onpostexecute(result);
}
}
private string[] mstrings = {
// "abbaye de belloc", "abbaye du mont des cats", "abertam",
// "abondance", "ackawi", "acorn", "adelost", "affidelice au chablis",
"afuega'l pitu", "airag", "airedale", "aisy cendre",
"allgauer emmentaler"};
}