Android中ListView下拉刷新的實現(xiàn)方法實例分析

更新時間：2015年10月17日 17:40:07 作者：非著名程序員

這篇文章主要介紹了Android中ListView下拉刷新的實現(xiàn)方法,涉及Android操作ListView的相關(guān)技巧,具有一定參考借鑒價值,需要的朋友可以參考下

本文實例講述了Android中ListView下拉刷新的實現(xiàn)方法。分享給大家供大家參考，具體如下：

ListView中的下拉刷新是非常常見的，也是經(jīng)常使用的，看到有很多同學(xué)想要，那我就整理一下，供大家參考。那我就不解釋，直接上代碼了。

這里需要自己重寫一下ListView,重寫代碼如下:

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;// 下拉過程的狀態(tài)值 
 private final static int PULL_To_REFRESH = 1; // 從下拉返回到不刷新的狀態(tài)值
 private final static int REFRESHING = 2;// 正在刷新的狀態(tài)值 
 private final static int DONE = 3; 
 private final static int LOADING = 4; 
 // 實際的padding的距離與界面上偏移距離的比例 
 private final static int RATIO = 3; 
 private LayoutInflater inflater; 
 // ListView頭部下拉刷新的布局 
 private LinearLayout headerView; 
 private TextView lvHeaderTipsTv; 
 private TextView lvHeaderLastUpdatedTv; 
 private ImageView lvHeaderArrowIv; 
 private ProgressBar lvHeaderProgressBar; 
 // 定義頭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; 
 // 用于保證startY的值在一個完整的touch事件中只被記錄一次 
 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); 
  // 設(shè)置下拉刷新圖標的最小高度和寬度 
  lvHeaderArrowIv.setMinimumWidth(70); 
  lvHeaderArrowIv.setMinimumHeight(50); 
  lvHeaderProgressBar = (ProgressBar) headerView 
    .findViewById(R.id.lvHeaderProgressBar); 
  measureView(headerView); 
  headerContentHeight = headerView.getMeasuredHeight(); 
  // 設(shè)置內(nèi)邊距，正好距離頂部為一個負的整個布局的高度，正好把頭部隱藏 
  headerView.setPadding(0, -1 * headerContentHeight, 0, 0); 
  // 重繪一下 
  headerView.invalidate(); 
  // 將下拉刷新的布局加入ListView的頂部 
  addHeaderView(headerView, null, false); 
  // 設(shè)置滾動監(jiān)聽事件 
  setOnScrollListener(this); 
  // 設(shè)置旋轉(zhuǎn)動畫事件 
  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); 
  // 一開始的狀態(tài)就是下拉刷新完的狀態(tài)，所以為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();// 手指按下時記錄當(dāng)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) { 
     // 保證在設(shè)置padding的過程中，當(dāng)前的位置一直是在head，否則如果當(dāng)列表超出屏幕的話，當(dāng)在上推的時候，列表會同時進行滾動 
     // 可以松手去刷新了 
     if (state == RELEASE_To_REFRESH) { 
      setSelection(0); 
      // 往上推了，推到了屏幕足夠掩蓋head的程度，但是還沒有推到全部掩蓋的地步 
      if (((tempY - startY) / RATIO < headerContentHeight)// 由松開刷新狀態(tài)轉(zhuǎn)變到下拉刷新狀態(tài) 
        && (tempY - startY) > 0) { 
       state = PULL_To_REFRESH; 
       changeHeaderViewByState(); 
      } 
      // 一下子推到頂了 
      else if (tempY - startY <= 0) {// 由松開刷新狀態(tài)轉(zhuǎn)變到done狀態(tài) 
       state = DONE; 
       changeHeaderViewByState(); 
      } 
     } 
     // 還沒有到達顯示松開刷新的時候,DONE或者是PULL_To_REFRESH狀態(tài) 
     if (state == PULL_To_REFRESH) { 
      setSelection(0); 
      // 下拉到可以進入RELEASE_TO_REFRESH的狀態(tài) 
      if ((tempY - startY) / RATIO >= headerContentHeight) {// 由done或者下拉刷新狀態(tài)轉(zhuǎn)變到松開刷新 
       state = RELEASE_To_REFRESH; 
       isBack = true; 
       changeHeaderViewByState(); 
      } 
      // 上推到頂了 
      else if (tempY - startY <= 0) {// 由DOne或者下拉刷新狀態(tài)轉(zhuǎn)變到done狀態(tài) 
       state = DONE; 
       changeHeaderViewByState(); 
      } 
     } 
     // done狀態(tài)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); 
 } 
 // 當(dāng)狀態(tài)改變時候，調(diào)用該方法，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();// 清除動畫 
   lvHeaderArrowIv.startAnimation(animation);// 開始動畫效果 
   lvHeaderTipsTv.setText("松開刷新"); 
   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狀態(tài)轉(zhuǎn)變來的 
   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; 
  } 
 } 
 // 此方法直接照搬自網(wǎng)絡(luò)上的一個下拉刷新的demo，此處是“估計”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); 
 } 
}

重寫完ListView之后，在布局文件中是這么使用的，頭部下拉刷新的布局文件lv_header.xml代碼如下：

<?xml version="1.0" encoding="utf-8"?> 
<!-- ListView的頭部 --> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 android:layout_width="fill_parent" 
 android:layout_height="wrap_content" 
 android:background="#000000" > 
 <!-- 內(nèi)容 --> 
 <RelativeLayout 
  android:id="@+id/head_contentLayout" 
  android:layout_width="fill_parent" 
  android:layout_height="wrap_content" 
  android:paddingLeft="30dp" > 
  <!-- 箭頭圖像、進度條 --> 
  <FrameLayout 
   android:layout_width="wrap_content" 
   android:layout_height="wrap_content" 
   android:layout_alignParentLeft="true" 
   android:layout_centerVertical="true" > 
   <!-- 箭頭 --> 
   <ImageView 
    android:id="@+id/lvHeaderArrowIv" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center" 
    android:src="@drawable/arrow" /> 
   <!-- 進度條 --> 
   <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中進行設(shè)置，代碼如下：

<?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中實現(xiàn)，代碼如下：

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("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)者"); 
  list.add("我們都是開發(fā)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("刷新后添加的內(nèi)容"); 
      return null; 
     } 
     @Override 
     protected void onPostExecute(Void result) { 
      adapter.notifyDataSetChanged(); 
      lv.onRefreshComplete(); 
     } 
    }.execute(null, null, null); 
   } 
  }); 
 }
}

這里還需要為ListView設(shè)置一下Adapter,自定義的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; 
 } 
}

到這里就完了，代碼中的解釋非常詳細，具體的我就不多說了，也不解釋了，自己看看并研究吧！

希望本文所述對大家Android程序設(shè)計有所幫助。

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