Android之ListView分页加载数据功能实现代码

<?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="match_parent"  tools:context="com.company.listviewdeepknow.MainActivity">  <ListView    android:id="@+id/mList"    android:layout_width="match_parent"    android:layout_height="match_parent">  </ListView></RelativeLayout>

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="match_parent"  android:layout_height="70dp"  android:gravity="center"  android:orientation="horizontal">  <ProgressBar    android:id="@+id/progressBar"    style="?android:attr/progressBarStyleSmall"    android:layout_width="45dp"    android:layout_height="45dp" />  <TextView    android:id="@+id/mLoad"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="加载更多..."    android:textSize="20sp" /></LinearLayout>

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="horizontal">  <TextView    android:id="@+id/mTv1"    android:layout_width="100dp"    android:layout_height="100dp"    android:textSize="20sp" />  <TextView    android:id="@+id/mTv2"    android:layout_width="100dp"    android:layout_height="100dp"    android:layout_alignParentRight="true"    android:textSize="20sp" /></RelativeLayout>

public class MainActivity extends AppCompatActivity implements MyOnScrollListener.OnloadDataListener {  //ListView展示的数据项  private List<Student> data;  //ListView控件  private ListView mList;  //自定义适配器  MyAdapter adapter;  //底部加载更多布局  View footer;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //首先加载默认数据，这里设置为10条    getData();    //显示到ListView上    showListView(data);    //自定义的滚动监听事件    MyOnScrollListener onScrollListener = new MyOnScrollListener(footer, data);    //设置接口回调    onScrollListener.setOnLoadDataListener(this);    //设置ListView的滚动监听事件    mList.setOnScrollListener(onScrollListener);  }  /**   * 初始化ListView数据，默认设置为10条   */  private void getData() {    data = new ArrayList<>();    Student stu = null;    for (int i = 0; i < 10; i++) {      stu = new Student();      stu.setName("姓名" + i);      stu.setSex(i % 2 == 0 ? "男" : "女");      data.add(stu);    }  }  /**   * 将数据加载到ListView上   *   * @param data   */  private void showListView(List<Student> data) {    //首先判断适配器是否为空，首次运行肯定是为空的    if (adapter == null) {      //查到ListView控件      mList = (ListView) findViewById(R.id.mList);      //将底部加载一个加载更多的布局      footer = LayoutInflater.from(this).inflate(R.layout.foot_boot, null);      //初始状态为隐藏      footer.setVisibility(View.GONE);      //加入到ListView的底部      mList.addFooterView(footer);      //创建adpter数据      adapter = new MyAdapter(data);      //设置adapter      mList.setAdapter(adapter);    } else {      //不为空，则刷新数据      this.data = data;      //提醒ListView重新更新数据      adapter.notifyDataSetChanged();    }  }  @Override  public void onLoadData(List<Student> data) {    //加载数据完成后，展示数据到ListView    showListView(data);  }}

public class MyOnScrollListener implements AbsListView.OnScrollListener {  //ListView总共显示多少条  private int totalItemCount;  //ListView最后的item项  private int lastItem;  //用于判断当前是否在加载  private boolean isLoading;  //底部加载更多布局  private View footer;  //接口回调的实例  private OnloadDataListener listener;  //数据  private List<Student> data;  public MyOnScrollListener(View footer, List<Student> data) {    this.footer = footer;    this.data = data;  }  //设置接口回调的实例  public void setOnLoadDataListener(OnloadDataListener listener) {    this.listener = listener;  }  /**   * 滑动状态变化   *   * @param view   * @param scrollState 1 SCROLL_STATE_TOUCH_SCROLL是拖动  2 SCROLL_STATE_FLING是惯性滑动 0SCROLL_STATE_IDLE是停止 , 只有当在不同状态间切换的时候才会执行   */  @Override  public void onScrollStateChanged(AbsListView view, int scrollState) {    //如果数据没有加载，并且滑动状态是停止的，而且到达了最后一个item项    if (!isLoading && lastItem == totalItemCount && scrollState == SCROLL_STATE_IDLE) {      //显示加载更多      footer.setVisibility(View.VISIBLE);      Handler handler = new Handler();      //模拟一个延迟两秒的刷新功能      handler.postDelayed(new Runnable() {        @Override        public void run() {          if (listener != null) {            //开始加载更多数据            loadMoreData();            //回调设置ListView的数据            listener.onLoadData(data);            //加载完成后操作什么            loadComplete();          }        }      }, 2000);    }  }  /**   * 当加载数据完成后，设置加载标志为false表示没有加载数据了   * 并且设置底部加载更多为隐藏   */  private void loadComplete() {    isLoading = false;    footer.setVisibility(View.GONE);  }  /**   * 开始加载更多新数据，这里每次只更新三条数据   */  private void loadMoreData() {    isLoading = true;    Student stu = null;    for (int i = 0; i < 3; i++) {      stu = new Student();      stu.setName("新名字" + i);      stu.setSex("新性别" + i);      data.add(stu);    }  }  /**   * 监听可见界面的情况   *   * @param view       ListView   * @param firstVisibleItem 第一个可见的 item 的索引   * @param visibleItemCount 可以显示的 item的条数   * @param totalItemCount  总共有多少个 item   */  @Override  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {    //当可见界面的第一个item + 当前界面多有可见的界面个数就可以得到最后一个item项了    lastItem = firstVisibleItem + visibleItemCount;    //总listView的item个数    this.totalItemCount = totalItemCount;  }  //回调接口  public interface OnloadDataListener {    void onLoadData(List<Student> data);  }}

public class MyAdapter extends MyBaseAdapter<Student> {  public MyAdapter(List<Student> data) {    super(data);  }  @Override  public void setData(ViewHolder holder, Student t) {    holder.setText(R.id.mTv1, t.getName()).setText(R.id.mTv2, t.getSex());  }}

public abstract class MyBaseAdapter<T> extends BaseAdapter {  protected List<T> data;  public MyBaseAdapter(List<T> data){    this.data = data;  }  @Override  public int getCount() {    return data == null ? 0 : data.size();  }  @Override  public Object getItem(int position) {    return data.get(position);  }  @Override  public long getItemId(int position) {    return position;  }  @Override  public View getView(int position, View convertView, ViewGroup parent) {    ViewHolder holder = ViewHolder.getHolder(convertView,parent,position, R.layout.list_item);    setData(holder,data.get(position));    return holder.getConvertView();  }  public abstract void setData(ViewHolder holder,T t);}

public class ViewHolder {  private int position;  private SparseArray<View> array;  private View convertView;  private Context context;  private ViewHolder(ViewGroup parent, int position, int layout) {    this.position = position;    this.context = parent.getContext();    convertView = LayoutInflater.from(parent.getContext()).inflate(layout, null);    convertView.setTag(this);    array = new SparseArray<>();  }  public static ViewHolder getHolder(View convertView, ViewGroup parent, int position, int layout) {    if (convertView == null) {      return new ViewHolder(parent, position, layout);    } else {      ViewHolder holder = (ViewHolder) convertView.getTag();      holder.position = position;      return holder;    }  }  public <T extends View> T getView(int viewId) {    View view = array.get(viewId);    if (view == null) {      view = convertView.findViewById(viewId);      array.put(viewId, view);    }    return (T) view;  }  public View getConvertView() {    return convertView;  }  public ViewHolder setText(int viewId, String data) {    TextView tv = getView(viewId);    tv.setText(data);    return this;  }

public class Student {  private String name;  private String sex;  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public String getSex() {    return sex;  }  public void setSex(String sex) {    this.sex = sex;  }}