Android中ListView下拉刷新的实现方法

listview中的下拉刷新是非常常见的，也是经常使用的，看到有很多同学想要，那我就整理一下，供大家参考。那我就不解释，直接上代码了。

这里需要自己重写一下listview,重写代码如下:

package net.loonggg.listview;

import java.util.date;

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.view.animation.linearinterpolator;
import android.view.animation.rotateanimation;
import android.widget.abslistview;
import android.widget.abslistview.onscrolllistener;
import android.widget.imageview;
import android.widget.linearlayout;
import android.widget.listview;
import android.widget.progressbar;
import android.widget.textview;

public class mylistview extends listview implements onscrolllistener {

 private final static int release_to_refresh = 0;// 下拉过程的状态值
 private final static int pull_to_refresh = 1; // 从下拉返回到不刷新的状态值
 private final static int refreshing = 2;// 正在刷新的状态值
 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;

 // listview头部下拉刷新的布局
 private linearlayout headerview;
 private textview lvheadertipstv;
 private textview lvheaderlastupdatedtv;
 private imageview lvheaderarrowiv;
 private progressbar lvheaderprogressbar;

 // 定义头部下拉刷新的布局的高度
 private int headercontentheight;

 private rotateanimation animation;
 private rotateanimation reverseanimation;

 private int starty;
 private int state;
 private boolean isback;

 // 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 onrefreshlistener refreshlistener;

 private boolean isrefreshable;

 public mylistview(context context) {
  super(context);
  init(context);
 }

 public mylistview(context context, attributeset attrs) {
  super(context, attrs);
  init(context);
 }

 private void init(context context) {
  setcachecolorhint(context.getresources().getcolor(r.color.transparent));
  inflater = layoutinflater.from(context);
  headerview = (linearlayout) inflater.inflate(r.layout.lv_header, null);
  lvheadertipstv = (textview) headerview
    .findviewbyid(r.id.lvheadertipstv);
  lvheaderlastupdatedtv = (textview) headerview
    .findviewbyid(r.id.lvheaderlastupdatedtv);

  lvheaderarrowiv = (imageview) headerview
    .findviewbyid(r.id.lvheaderarrowiv);
  // 设置下拉刷新图标的最小高度和宽度
  lvheaderarrowiv.setminimumwidth(70);
  lvheaderarrowiv.setminimumheight(50);

  lvheaderprogressbar = (progressbar) headerview
    .findviewbyid(r.id.lvheaderprogressbar);
  measureview(headerview);
  headercontentheight = headerview.getmeasuredheight();
  // 设置内边距，正好距离顶部为一个负的整个布局的高度，正好把头部隐藏
  headerview.setpadding(0, -1 * headercontentheight, 0, 0);
  // 重绘一下
  headerview.invalidate();
  // 将下拉刷新的布局加入listview的顶部
  addheaderview(headerview, null, false);
  // 设置滚动监听事件
  setonscrolllistener(this);

  // 设置旋转动画事件
  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);

  // 一开始的状态就是下拉刷新完的状态，所以为done
  state = done;
  // 是否正在刷新
  isrefreshable = false;
 }

 @override
 public void onscrollstatechanged(abslistview view, int scrollstate) {

 }

 @override
 public void onscroll(abslistview view, int firstvisibleitem,
   int visibleitemcount, int totalitemcount) {
    if (firstvisibleitem == 0) {
     isrefreshable = true;
     } else {
     isrefreshable = false;
     }
  }

 @override
 public boolean ontouchevent(motionevent ev) {
  if (isrefreshable) {
   switch (ev.getaction()) {
   case motionevent.action_down:
    if (!isrecored) {
     isrecored = true;
     starty = (int) ev.gety();// 手指按下时记录当前位置
    }
    break;
   case motionevent.action_up:
    if (state != refreshing && state != loading) {
     if (state == pull_to_refresh) {
      state = done;
      changeheaderviewbystate();
     }
     if (state == release_to_refresh) {
      state = refreshing;
      changeheaderviewbystate();
      onlvrefresh();
     }
    }
    isrecored = false;
    isback = false;

    break;

   case motionevent.action_move:
    int tempy = (int) ev.gety();
    if (!isrecored) {
     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 < headercontentheight)// 由松开刷新状态转变到下拉刷新状态
        && (tempy - starty) > 0) {
       state = pull_to_refresh;
       changeheaderviewbystate();
      }
      // 一下子推到顶了
      else if (tempy - starty <= 0) {// 由松开刷新状态转变到done状态
       state = done;
       changeheaderviewbystate();
      }
     }
     // 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 >= headercontentheight) {// 由done或者下拉刷新状态转变到松开刷新
       state = release_to_refresh;
       isback = true;
       changeheaderviewbystate();
      }
      // 上推到顶了
      else if (tempy - starty <= 0) {// 由done或者下拉刷新状态转变到done状态
       state = done;
       changeheaderviewbystate();
      }
     }
     // 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) {
      headerview.setpadding(0, -1 * headercontentheight
        + (tempy - starty) / ratio, 0, 0);

     }
     // 更新headview的paddingtop
     if (state == release_to_refresh) {
      headerview.setpadding(0, (tempy - starty) / ratio
        - headercontentheight, 0, 0);
     }

    }
    break;

   default:
    break;
   }
  }
  return super.ontouchevent(ev);
 }

 // 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:
   lvheaderarrowiv.setvisibility(view.visible);
   lvheaderprogressbar.setvisibility(view.gone);
   lvheadertipstv.setvisibility(view.visible);
   lvheaderlastupdatedtv.setvisibility(view.visible);

   lvheaderarrowiv.clearanimation();// 清除动画
   lvheaderarrowiv.startanimation(animation);// 开始动画效果

   lvheadertipstv.settext("松开刷新");
   break;
  case pull_to_refresh:
   lvheaderprogressbar.setvisibility(view.gone);
   lvheadertipstv.setvisibility(view.visible);
   lvheaderlastupdatedtv.setvisibility(view.visible);
   lvheaderarrowiv.clearanimation();
   lvheaderarrowiv.setvisibility(view.visible);
   // 是由release_to_refresh状态转变来的
   if (isback) {
    isback = false;
    lvheaderarrowiv.clearanimation();
    lvheaderarrowiv.startanimation(reverseanimation);

    lvheadertipstv.settext("下拉刷新");
   } else {
    lvheadertipstv.settext("下拉刷新");
   }
   break;

  case refreshing:

   headerview.setpadding(0, 0, 0, 0);

   lvheaderprogressbar.setvisibility(view.visible);
   lvheaderarrowiv.clearanimation();
   lvheaderarrowiv.setvisibility(view.gone);
   lvheadertipstv.settext("正在刷新...");
   lvheaderlastupdatedtv.setvisibility(view.visible);
   break;
  case done:
   headerview.setpadding(0, -1 * headercontentheight, 0, 0);

   lvheaderprogressbar.setvisibility(view.gone);
   lvheaderarrowiv.clearanimation();
   lvheaderarrowiv.setimageresource(r.drawable.arrow);
   lvheadertipstv.settext("下拉刷新");
   lvheaderlastupdatedtv.setvisibility(view.visible);
   break;
  }
 }

 // 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 params = child.getlayoutparams();
  if (params == null) {
   params = new viewgroup.layoutparams(
     viewgroup.layoutparams.fill_parent,
     viewgroup.layoutparams.wrap_content);
  }
  int childwidthspec = viewgroup.getchildmeasurespec(0, 0 + 0,
    params.width);
  int lpheight = params.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 setonrefreshlistener(onrefreshlistener refreshlistener) {
  this.refreshlistener = refreshlistener;
  isrefreshable = true;
 }

 public interface onrefreshlistener {
  public void onrefresh();
 }

 public void onrefreshcomplete() {
  state = done;
  lvheaderlastupdatedtv.settext("最近更新:" + new date().tolocalestring());
  changeheaderviewbystate();
 }

 private void onlvrefresh() {
  if (refreshlistener != null) {
   refreshlistener.onrefresh();
  }
 }

 public void setadapter(lvadapter adapter) {
  lvheaderlastupdatedtv.settext("最近更新:" + new date().tolocalestring());
  super.setadapter(adapter);
 }

}

重写完listview之后，在布局文件中是这么使用的，头部下拉刷新的布局文件lv_header.xml代码如下：

<?xml version="1.0" encoding="utf-8"?>
<!-- listview的头部 -->
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:background="#000000" >

 <!-- 内容 -->

 <relativelayout
  android:id="@+id/head_contentlayout"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:paddingleft="30dp" >

  <!-- 箭头图像、进度条 -->

  <framelayout
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_alignparentleft="true"
   android:layout_centervertical="true" >

   <!-- 箭头 -->

   <imageview
    android:id="@+id/lvheaderarrowiv"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:src="@drawable/arrow" />

   <!-- 进度条 -->

   <progressbar
    android:id="@+id/lvheaderprogressbar"
    style="?android:attr/progressbarstylesmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:visibility="gone" />
  </framelayout>

  <!-- 提示、最近更新 -->

  <linearlayout
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_centerhorizontal="true"
   android:gravity="center_horizontal"
   android:orientation="vertical" >

   <!-- 提示 -->

   <textview
    android:id="@+id/lvheadertipstv"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="下拉刷新"
    android:textcolor="@color/white"
    android:textsize="20sp" />

   <!-- 最近更新 -->

   <textview
    android:id="@+id/lvheaderlastupdatedtv"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="上次更新"
    android:textcolor="@color/gold"
    android:textsize="10sp" />
  </linearlayout>
 </relativelayout>

</linearlayout>

在main.xml中进行设置，代码如下：

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:background="#000000"
 android:orientation="vertical" >

 <net.loonggg.listview.mylistview
  android:id="@+id/lv"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent" />

</linearlayout>

然后就是在mainactivity中实现，代码如下：

package net.loonggg.listview;

import java.util.arraylist;
import java.util.list;

import net.loonggg.listview.mylistview.onrefreshlistener;
import android.app.activity;
import android.os.asynctask;
import android.os.bundle;
import android.view.view;

public class mainactivity extends activity {
 private list<string> list;
 private mylistview lv;
 private lvadapter adapter;

 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);
  lv = (mylistview) findviewbyid(r.id.lv);
  list = new arraylist<string>();
  list.add("loonggg");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  list.add("我们都是开发者");
  adapter = new lvadapter(list, this);
  lv.setadapter(adapter);

  lv.setonrefreshlistener(new onrefreshlistener() {

   @override
   public void onrefresh() {
    new asynctask<void, void, void>() {
     protected void doinbackground(void... params) {
      try {
       thread.sleep(1000);
      } catch (exception e) {
       e.printstacktrace();
      }
      list.add("刷新后添加的内容");
      return null;
     }

     @override
     protected void onpostexecute(void result) {
      adapter.notifydatasetchanged();
      lv.onrefreshcomplete();
     }
    }.execute(null, null, null);
   }
  });
 }
}

这里还需要为listview设置一下adapter,自定义的adapter如下：

package net.loonggg.listview;

import java.util.list;

import android.content.context;
import android.view.view;
import android.view.viewgroup;
import android.widget.baseadapter;
import android.widget.textview;

public class lvadapter extends baseadapter {
 private list<string> list;
 private context context;

 public lvadapter(list<string> list, context context) {
  this.list = list;
  this.context = context;
 }

 @override
 public int getcount() {
  return list.size();
 }

 @override
 public object getitem(int position) {
  return list.get(position);
 }

 @override
 public long getitemid(int position) {
  return position;
 }

 @override
 public view getview(int position, view convertview, viewgroup parent) {
  textview tv = new textview(context.getapplicationcontext());
  tv.settext(list.get(position));
  return tv;
 }

}

到这里就完了，代码中的解释非常详细，具体的我就不多说了，也不解释了，自己看看并研究吧！