android中ListView在劃屏到底部的時候動態添加ListView的Item實現

ListView中我們可以添加我們自己的adpter，這樣我們可以豐富我們的ListView的Item，並且如果我們的ListView很長的時候。如果一下子都顯示出來的話，那麼我們要通過劃屏滾動很長時間才能看到我們要的數據(我們的數據如果在最下邊)，有時候我們的數據就在前幾行，那麼我們有必要把全部數據都顯示在ListView中麼？如果我們的數據是從網絡獲取，或者通過開的線程，耗時性很長的操作才能返回數據的呢？這就要求我們在沒有全部加載必要的情況下部分加載ListView中的內容，通過activity實現OnScrollListener這個接口我們可是在劃屏到最底下的時候設置加載來實現動態的添加ListView中的數據。

很簡單的例子，通過ListView顯示出我們的android手機中都安裝了哪些的應用，然後返回。通過瀏覽到最底部的時候觸發OnScrollListener事件，我們就會把更多的應用添加到ListView中去。

直接看代碼：

package com.jftt.listviewupdate;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.Toast;
import android.widget.AbsListView.OnScrollListener;
import android.widget.AdapterView.OnItemClickListener;

public class ListViewUpdate extends Activity implements OnScrollListener,
		OnItemClickListener {
	private List<ApplicationItemInfo> applicationItemInfoList;
	private List<ApplicationItemInfo> applicationItemInfoListTemp;
	private ApplicationItemAdapter applicationItemAdapter;
	private Handler handler;

	private ListView listView;

	private LinearLayout loading;
	private boolean refreshable;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		init();
		updateApplicationItemInfoList();
	}

	private void init() {
		setContentView(R.layout.main);
		listView = (ListView) findViewById(R.id.list);
		loading = (LinearLayout) findViewById(R.id.loading);

		applicationItemInfoList = new ArrayList<ApplicationItemInfo>();
		applicationItemAdapter = new ApplicationItemAdapter(this,
				applicationItemInfoList);
		handler = createHandler();
		refreshable = true;

		listView.setAdapter(applicationItemAdapter);
		listView.setOnItemClickListener(this);
		listView.setOnScrollListener(this);
	}

	private Handler createHandler() {
		Handler handler = new Handler() {
			@Override
			public void handleMessage(Message msg) {
				super.handleMessage(msg);
				switch (msg.what) {
				case 1:
					if (applicationItemInfoListTemp != null) {
						ListViewUpdate.this.applicationItemInfoList
								.addAll(applicationItemInfoListTemp);
						ListViewUpdate.this.applicationItemAdapter
								.notifyDataSetChanged();
						ListViewUpdate.this.loading.setVisibility(View.GONE);
						ListViewUpdate.this.refreshable = true;
					} else {
						ListViewUpdate.this.loading.setVisibility(View.GONE);
						Toast.makeText(ListViewUpdate.this,
								"All of applications have been shown!",
								Toast.LENGTH_LONG).show();
					}
					break;
				default:
					break;
				}
			}
		};
		return handler;
	}

	public Handler getHandler() {
		return handler;
	}

	private void updateApplicationItemInfoList() {
		new Thread(new Runnable() {

			@Override
			public void run() {
				if (ListViewUpdate.this.applicationItemInfoList.size() < 80) {
					ListViewUpdate.this.applicationItemInfoListTemp = ListViewUpdate.this
							.getLocalApplicationInfo();
				} else {
					ListViewUpdate.this.applicationItemInfoListTemp = null;
				}

				try {
					Thread.sleep(5000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}

				Message message = new Message();
				message.what = 1;
				ListViewUpdate.this.getHandler().sendMessage(message);
			}

		}).start();
	}

	private ArrayList<ApplicationItemInfo> getLocalApplicationInfo() {

		PackageManager packageManager = this.getPackageManager();
		ArrayList<ApplicationItemInfo> applicationItemInfoList = new ArrayList<ApplicationItemInfo>();
		List<PackageInfo> packageInfoList = packageManager
				.getInstalledPackages(0);

		for (int i = packageInfoList.size(); i > 0; i--) {

			ApplicationInfo applicationInfo = packageInfoList.get(i - 1).applicationInfo;

			if ((applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) <= 0) {
				try {
					ApplicationItemInfo applicationItemInfo = new ApplicationItemInfo();

					String packageName = packageInfoList.get(i - 1).packageName;
					String[] permissions = packageManager.getPackageInfo(
							packageName, PackageManager.GET_PERMISSIONS).requestedPermissions;

					applicationItemInfo.setPackageName(packageName);
					applicationItemInfo.setPermissions(permissions);

					applicationItemInfo.setIcon(packageManager
							.getApplicationIcon(applicationInfo));
					applicationItemInfo.setName(packageManager
							.getApplicationLabel(applicationInfo).toString());

					applicationItemInfoList.add(applicationItemInfo);

				} catch (NameNotFoundException e) {
					// TODO Auto-generated catch block
				}
			}
		}
		if ((!applicationItemInfoList.isEmpty())
				&& (applicationItemInfoList.size() < 10)) {
			for (int i = applicationItemInfoList.size(); i < 10; i++) {
				applicationItemInfoList.add(applicationItemInfoList.get(9 - i));
			}
		}
		return applicationItemInfoList;
	}

	@Override
	public void onScroll(AbsListView view, int firstVisibleItem,
			int visibleItemCount, int totalItemCount) {
		// TODO Auto-generated method stub
		if ((firstVisibleItem + visibleItemCount == totalItemCount)
				&& (totalItemCount != 0)) {
			if (refreshable) {
				refreshable = false;
				loading.setVisibility(View.VISIBLE);
				updateApplicationItemInfoList();
			}
		}
	}

	@Override
	public void onScrollStateChanged(AbsListView view, int scrollState) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onItemClick(AdapterView<?> arg0, View view, int position,
			long id) {
		// TODO Auto-generated method stub
		AlertDialog.Builder permissionDialog = new AlertDialog.Builder(this);
		permissionDialog.setIcon(applicationItemInfoList.get(position)
				.getIcon());
		permissionDialog.setTitle(applicationItemInfoList.get(position)
				.getName());
		String[] permissions = applicationItemInfoList.get(position)
				.getPermissions();

		StringBuffer temp = new StringBuffer();
		if (permissions != null) {
			for (int i = 0; i < permissions.length; i++) {
				temp.append(permissions[i]);
				temp.append("\n");
			}
		} else {
			temp.append("permission is null");
		}
		permissionDialog.setMessage(temp.toString());
		permissionDialog.setPositiveButton("OK",
				new DialogInterface.OnClickListener() {

					@Override
					public void onClick(DialogInterface dialog, int which) {
						// TODO Auto-generated method stub
						dialog.cancel();
					}
				});
		permissionDialog.create().show();
	}
}

package com.jftt.listviewupdate;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class ApplicationItemAdapter extends BaseAdapter {

	private LayoutInflater layoutInflater;
	private List<ApplicationItemInfo> applicationItemInfoList;

	public ApplicationItemAdapter(Context context,
			List<ApplicationItemInfo> applicationItemInfoList) {

		this.applicationItemInfoList = applicationItemInfoList;
		layoutInflater = LayoutInflater.from(context);

	}

	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return applicationItemInfoList.size();
	}

	@Override
	public Object getItem(int position) {
		// TODO Auto-generated method stub
		return applicationItemInfoList.get(position);
	}

	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return position;
	}

	@Override
	public View getView(int position, View view, ViewGroup viewGroup) {

		ViewHolder viewHolder;

		// TODO Auto-generated method stub
		if (view == null) {
			view = layoutInflater.inflate(R.layout.application_item, null);
			viewHolder = new ViewHolder();
			viewHolder.icon = (ImageView) view.findViewById(R.id.icon);
			viewHolder.title = (TextView) view.findViewById(R.id.title);
			viewHolder.packageName = (TextView) view
					.findViewById(R.id.packagename);
			view.setTag(viewHolder);
		} else {
			viewHolder = (ViewHolder) view.getTag();
		}

		viewHolder.icon.setImageDrawable(applicationItemInfoList.get(position)
				.getIcon());
		viewHolder.title.setText(applicationItemInfoList.get(position)
				.getName());
		viewHolder.packageName.setText(applicationItemInfoList.get(position)
				.getPackageName());

		return view;
	}

	private class ViewHolder {
		ImageView icon;
		TextView title;
		TextView packageName;
	}

}

package com.jftt.listviewupdate;

import java.io.Serializable;

import android.graphics.drawable.Drawable;

public class ApplicationItemInfo implements Serializable {

	private static final long serialVersionUID = -738265888959292655L;

	private Drawable icon;

	private String packageName;

	private String name;

	private String[] permissions;

	public Drawable getIcon() {
		return icon;
	}

	public void setIcon(Drawable icon) {
		this.icon = icon;
	}

	public String getPackageName() {
		return packageName;
	}

	public void setPackageName(String packageName) {
		this.packageName = packageName;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String[] getPermissions() {
		return permissions;
	}

	public void setPermissions(String[] permissions) {
		this.permissions = permissions;
	}

}

• ListViewUpdate.zip (63 KB)
• 下載次數: 550