Android中ListView下拉刷新的实现代码

Android中ListView下拉刷新

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);
  } 

}

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！

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