【Android进阶】Listview分页加载数据的实现

Listview分页加载数据的实现

public class MainActivity extends Activity {
	protected static final int SUCCESS_GET_DATA = 0;
	private ListView listview;
	private DataService service;
	private List<String> data;// 加载的总数据
	private ArrayAdapter<String> adapter;

	private boolean finish = true;// 是否加载完成

	private View footer;

	private Handler mHandler = new Handler() {
		public void handleMessage(android.os.Message msg) {
			switch (msg.what) {
			case SUCCESS_GET_DATA:
				@SuppressWarnings("unchecked")
				ArrayList<String> result = ((ArrayList<String>) msg.obj);
				data.addAll(result);
				// 让listview自动刷新
				adapter.notifyDataSetChanged();
				finish = true;
				// 将页脚删除掉
				if (listview.getFooterViewsCount() > 0) {
					listview.removeFooterView(footer);
				}
				break;

			default:
				break;
			}
		};
	};

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		listview = (ListView) findViewById(R.id.listview);
		service = new DataService();
		data = new ArrayList<String>();
		List<String> result = service.getData(0, 20);
		data.addAll(result);
		adapter = new ArrayAdapter<String>(this, R.layout.item, R.id.tv_info,
				data);
		footer = View.inflate(this, R.layout.footer, null);
		// 在增加listview的页脚之前，需要提前设置一次
		listview.addFooterView(footer);
		listview.setAdapter(adapter);
		// 然后再次将页脚删除掉
		listview.removeFooterView(footer);
		// 滚动监听事件
		listview.setOnScrollListener(new MyOnScrollListener());
	}

	private final class MyOnScrollListener implements OnScrollListener {
		// 加载的总页数
		private int countPage = 5;
		// 每页加载20条数据
		private int pageSize = 20;

		// 滚动状态发生改变时
		public void onScrollStateChanged(AbsListView view, int scrollState) {
			Log.i("i", " scrollState " + scrollState);
		}

		// 当list开始滚动时
		public void onScroll(AbsListView view, int firstVisibleItem,
				int visibleItemCount, int totalItemCount) {
			// 最下面的条目数
			final int totalCount = firstVisibleItem + visibleItemCount;
			int currentPage = totalCount / pageSize;// 当前页
			int nextPage = currentPage + 1;// 下一页
			// 当翻到最后一条数据时
			if (totalCount == totalItemCount && nextPage <= countPage && finish) {
				// 已经移动到了listview的最后
				finish = false;
				// 添加页脚
				listview.addFooterView(footer);
				new Thread() {
					public void run() {
						SystemClock.sleep(3000);
						List<String> result = service.getData(totalCount + 1,
								pageSize);
						Message msg = new Message();
						msg.what = SUCCESS_GET_DATA;
						msg.obj = result;
						mHandler.sendMessage(msg);
					};
				}.start();
			}
		}
	}
}

数据服务类，这里进行数据的模拟获取

public class DataService {

	//加载数据
	public List<String> getData(int startPosition ,int offset){
		List<String> data = new ArrayList<String>();
		for(int i = 0;i< 20;i++){
			data.add("分页加载的数据   " + i);
		}
		return data;
	}
}

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