Android中ListView下拉刷新

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实现效果图：

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); 
  } 
 
} 

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