Android ListView 实现上拉加载的示例代码

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:paddingBottom="10dp"
  android:paddingTop="10dp">

  <LinearLayout
    android:id="@+id/layout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="10dp"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
      android:id="@+id/tv_tip"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="下拉可以刷新"
      android:textSize="12sp" />
  </LinearLayout>

  <ImageView
    android:id="@+id/img_arrow"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginRight="10dp"
    android:layout_toLeftOf="@+id/layout"
    android:src="@drawable/pull_to_refresh_arrow" />

  <ProgressBar
    android:id="@+id/progress"
    
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerVertical="true"
    android:layout_marginRight="10dp"
    android:layout_toLeftOf="@+id/img_arrow"
    android:visibility="gone"
    tools:visibility="visible" />
</RelativeLayout>

public class RefreshListView extends ListView {
  private View header;
  private int headerHeight;//顶部布局高度
  private int firstVisibleItem;//当前第一个 Item 可见位置
  private float startY;//按下时开始的Y值
  private int scrollState;//当前滚动状态
  
  private View footer;
  private int footerHeight;//底部布局高度
  private float lastY;
  private boolean canLoadMoreEnabled;//是否允许加载更多
  
  public RefreshListView(Context context) {
    super(context);
    initView(context);
  }

  public RefreshListView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initView(context);
  }

  public RefreshListView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    initView(context);
  }


  private void initView(Context context) {
    header = LayoutInflater.from(context).inflate(R.layout.header_layout, null);
    footer = LayoutInflater.from(context).inflate(R.layout.footer_layout, null);
    measureView(header);
    measureView(footer);
    //这里获取高度的时候需要先通知父布局header占用的空间
    headerHeight = header.getMeasuredHeight();
    footerHeight = footer.getMeasuredHeight();
    topPadding(-headerHeight);
    bottomPadding(-footerHeight);//用于隐藏 Footer
    this.addHeaderView(header);
    this.addFooterView(footer);
    this.setOnScrollListener(this);
  }
  
  /**
   * 设置 Footer 布局的下边距
   * 以隐藏 Footer
   * @param topPadding
   */
  private void bottomPadding(int bottomPadding) {
    footer.setPadding(footer.getPaddingLeft(), footer.getPaddingTop(),
        footer.getPaddingRight(),
        bottomPadding);
    footer.invalidate();
  }
}

public class RefreshListView extends ListView implements AbsListView.OnScrollListener {
  private int firstVisibleItem;//当前第一个 Item 可见位置
  private int scrollState;//当前滚动状态
  
  private void initView(Context context) {
    header = LayoutInflater.from(context).inflate(R.layout.header_layout, null);
    footer = LayoutInflater.from(context).inflate(R.layout.footer_layout, null);
    measureView(header);
    measureView(footer);
    //这里获取高度的时候需要先通知父布局header占用的空间
    headerHeight = header.getMeasuredHeight();
    footerHeight = footer.getMeasuredHeight();
    topPadding(-headerHeight);
    bottomPadding(-footerHeight);
    this.addHeaderView(header);
    this.addFooterView(footer);
    this.setOnScrollListener(this);
  }
  
  @Override
  public void onScrollStateChanged(AbsListView view, int scrollState) {
    this.scrollState = scrollState;
  }

  @Override
  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
    this.firstVisibleItem = firstVisibleItem;
    this.lastVisibleItem = firstVisibleItem + visibleItemCount;
    this.totalItemCount = totalItemCount;
  }
}

private float lastY;

private static int state;//当前状态
private final static int NONE = 0;//正常状态
private final static int PULL = 1;//下拉状态
private final static int RELEASE = 2;//释放状态
private final static int REFRESHING = 3;//正在刷新状态

@Override
  public boolean onTouchEvent(MotionEvent ev) {
    switch (ev.getAction()) {
      case MotionEvent.ACTION_DOWN:
        //最顶部
        if (firstVisibleItem == 0) {//刷新
          canRefreshEnabled = true;
          startY = ev.getY();
        } else if (lastVisibleItem == totalItemCount) {//加载更多
          canLoadMoreEnabled = true;
          lastY = ev.getY();
        }
        break;
      case MotionEvent.ACTION_MOVE:
        onMove(ev);
        break;
      case MotionEvent.ACTION_UP:
        if (state == RELEASE) {//如果已经释放，则可以提示刷新数据
          state = REFRESHING;
          if (iRefreshListener != null) {
            iRefreshListener.onRefresh();
          }
          if (iLoadMoreListener != null) {
            iLoadMoreListener.onLoadMore();
          }
        } else if (state == PULL) {//如果是在下拉状态，不刷新数据
          state = NONE;
        }
        if (canRefreshEnabled) {
          refreshViewByState();
        }
        if (canLoadMoreEnabled) {
          loadViewByState();
        }
        canLoadMoreEnabled = false;
        canRefreshEnabled = false;
        break;
    }
    return super.onTouchEvent(ev);
  }

  /**
   * 判断移动过程中的操作
   *
   * @param ev
   */
  private void onMove(MotionEvent ev) {
    int tempY = (int) ev.getY();
    int refreshSpace = (int) (tempY - startY);//向下移动的距离
    int topPadding = refreshSpace - headerHeight;//在移动过程中不断设置 topPadding
    int loadSpace = (int) (lastY - tempY);//向上移动的距离
    int bottomPadding = loadSpace - footerHeight;//在移动过程中不断设置 bottomPadding
    switch (state) {
      case NONE:
        //下拉移动距离大于0
        if (refreshSpace > 0) {
          state = PULL; //状态变成下拉状态
          refreshViewByState();
        }
        //上拉移动距离大于0
        if (loadSpace > 0) {
          state = PULL;//状态变成下拉状态
          loadViewByState();
        }
        break;
      case PULL:
        if (canRefreshEnabled) {
          topPadding(topPadding);//在移动过程中不断设置 topPadding，让 Header 随着下拉动作慢慢显示
        }
        if (canLoadMoreEnabled) {
          bottomPadding(bottomPadding);//在移动过程中不断设置 bottomPadding，让 Footer 随着上拉动作慢慢显示
        }
        //移动距离大于headerHeight并且正在滚动
        if (canRefreshEnabled && refreshSpace > (headerHeight + 30) && scrollState == SCROLL_STATE_TOUCH_SCROLL) {
          state = RELEASE;//提示释放
          refreshViewByState();
        }
        //移动距离大于footerHeight并且正在滚动
        if (canLoadMoreEnabled && loadSpace > footerHeight + 30 && scrollState == SCROLL_STATE_TOUCH_SCROLL) {
          state = RELEASE;//提示释放
          loadViewByState();//刷新footer布局
        }
        break;
      case RELEASE:
        if (canRefreshEnabled) {
          topPadding(topPadding);
          //移动距离小于headerHeight
          if (refreshSpace < headerHeight + 30) {
            state = PULL;//提示下拉
          } else if (refreshSpace <= 0) {
            state = NONE;
          }
          refreshViewByState();//更新header
        }
        if (canLoadMoreEnabled) {
          bottomPadding(bottomPadding);
          //移动距离小于footerHeight
          if (loadSpace < footerHeight + 30) {
            state = PULL;//提示下拉
          } else if (loadSpace <= 0) {
            state = NONE;
          }
          loadViewByState();//更新footer
        }
        break;
    }
  }

private void loadViewByState() {
    TextView tip = footer.findViewById(R.id.tv_tip);
    ImageView arrow = footer.findViewById(R.id.img_arrow);
    ProgressBar progressBar = footer.findViewById(R.id.progress);
    progressBar.setBackgroundResource(R.drawable.custom_progress_bar);
    AnimationDrawable animationDrawable = (AnimationDrawable) progressBar.getBackground();
    //给箭头设置动画
    RotateAnimation anim = new RotateAnimation(0, 180,
        RotateAnimation.RELATIVE_TO_SELF, 0.5f,
        RotateAnimation.RELATIVE_TO_SELF, 0.5f);
    RotateAnimation anim1 = new RotateAnimation(180, 0,
        RotateAnimation.RELATIVE_TO_SELF, 0.5f,
        RotateAnimation.RELATIVE_TO_SELF, 0.5f);
    anim.setDuration(200);
    anim.setFillAfter(true);
    anim1.setDuration(200);
    anim1.setFillAfter(true);
    switch (state) {
      case NONE://正常，footer不显示
        bottomPadding(-footerHeight);
        arrow.clearAnimation();
        break;
      case PULL://下拉状态
        arrow.setVisibility(VISIBLE);//箭头显示，进度条隐藏
        progressBar.setVisibility(GONE);
        if (animationDrawable.isRunning()) {
          animationDrawable.stop();
        }
        tip.setText("上拉可以加载");
        arrow.clearAnimation();
        arrow.setAnimation(anim);//箭头向下
        break;
      case RELEASE://释放状态
        arrow.setVisibility(VISIBLE);//箭头显示，进度条隐藏
        progressBar.setVisibility(GONE);
        if (animationDrawable.isRunning()) {
          //停止动画播放
          animationDrawable.stop();
        }
        tip.setText("松开开始加载");
        arrow.clearAnimation();
        arrow.setAnimation(anim);//箭头向上
        break;
      case REFRESHING://刷新状态
        bottomPadding(50);
        arrow.setVisibility(GONE);//箭头显示，进度条隐藏
        progressBar.setVisibility(VISIBLE);
        animationDrawable.start();
        tip.setText("正在加载...");
        arrow.clearAnimation();
        break;
    }
  }

private ILoadMoreListener iLoadMoreListener;

  public void setILoadMoreListener(ILoadMoreListener iLoadMoreListener) {
    this.iLoadMoreListener = iLoadMoreListener;
  }

  public interface ILoadMoreListener {
    void onLoadMore();
  }

package com.dali.refreshandloadmorelistview;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;

import java.util.ArrayList;

public class MainActivity extends Activity implements RefreshListView.IRefreshListener, RefreshListView.ILoadMoreListener {

  private ArrayList<ApkEntity> apk_list;
  private ListAdapter adapter;
  private RefreshListView listView;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    setData();
    showList(apk_list);
  }

  private void showList(ArrayList<ApkEntity> apk_list) {
    if (adapter == null) {
      listView = (RefreshListView) findViewById(R.id.listview);
      listView.setIRefreshListener(this);
      listView.setILoadMoreListener(this);
      adapter = new ListAdapter(this, apk_list);
      listView.setAdapter(adapter);
    } else {
      adapter.onDateChange(apk_list);
    }
  }

  private void setData() {
    apk_list = new ArrayList<ApkEntity>();
    for (int i = 0; i < 10; i++) {
      ApkEntity entity = new ApkEntity();
      entity.setName("默认数据" + i);
      entity.setDes("这是一个神奇的应用");
      entity.setInfo("50w用户");
      apk_list.add(entity);
    }
  }

  private void setRefreshData() {
    for (int i = 0; i < 2; i++) {
      ApkEntity entity = new ApkEntity();
      entity.setName("默认数据 + 刷新" + i);
      entity.setDes("这是一个神奇的应用");
      entity.setInfo("50w用户");
      apk_list.add(0, entity);
    }
  }

  private void setLoadData() {
    for (int i = 0; i < 2; i++) {
      ApkEntity entity = new ApkEntity();
      entity.setName("默认数据 + 加载" + (adapter.getCount() + i));
      entity.setDes("这是一个神奇的应用");
      entity.setInfo("50w用户");
      apk_list.add(entity);
    }
  }

  @Override
  public void onRefresh() {
    //添加刷新动画效果
    Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
      @Override
      public void run() {
        //获取最新数据
        setRefreshData();
        //通知界面显示数据
        showList(apk_list);
        //通知 ListView 刷新完成
        listView.refreshComplete();
      }
    }, 2000);
  }

  @Override
  public void onLoadMore() {
    Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
      @Override
      public void run() {
        //获取最新数据
        setLoadData();
        //通知界面显示数据
        showList(apk_list);
        //通知 ListView 刷新完成
        listView.loadMoreComplete();
      }
    }, 2000);
  }
}