Android中ProgressDialog的用法

本文的代碼接著上一篇獲取聯系人信息寫的。在獲取聯系人信息的時候，我發現遍歷Cursor來獲取所有聯系人的信息比較慢，比如我手機上有大約不到四百人的聯系方式，全部遍歷一次大約需要十多秒的時間。之前查了一下，暫時沒有找到太好的優化的辦法。我就想要不在遍歷聯系人信息的時候，在界面上顯示一個進度條，這樣用戶可以看到程序在一直運行，而不是誤認為程序死掉了。

在本篇的代碼中，主要是在獲取聯系人信息代碼的基礎上加上了一個ProgressDialog。代碼比較簡單，就不仔細說明了，下面看代碼：

package com.example.contactlist;

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

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.database.Cursor;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.provider.ContactsContract;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class Loading extends ListActivity {
	Context myContext = null;
	MyListAdapter myListAdapter = null;
	ViewHolder viewHolder = null;

	private ProgressDialog progressDialog = null;

	// 用於存儲聯系人名稱
	List myContactName = new ArrayList();
	// 用於存儲聯系人電話
	List myContactNumber = new ArrayList();
	// 用於存儲聯系人總數
	int myContactAmount = 0;

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		getContactList();

	}

	/**
	 * 用Handler來更新UI
	 */
	private Handler handler = new Handler() {

		@Override
		public void handleMessage(Message msg) {

			// 通過arg1來判斷是繼續更新進度，還是顯示聯系人列表
			switch (msg.arg1) {
			case 1:
				progressDialog.setProgress(msg.arg2);
				break;
			case 2:
				myListAdapter = new MyListAdapter(Loading.this);
				setListAdapter(myListAdapter);
				break;
			}

		}
	};

	/**
	 * 點擊按鈕事件listener
	 */
	private void getContactList() {

		// 顯示ProgressDialog
		progressDialog = new ProgressDialog(Loading.this);
		progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
		progressDialog.setTitle("正在獲取聯系人信息，請稍等：");
		progressDialog.setIndeterminate(false);
		progressDialog.show();

		final Cursor cursor = getContentResolver().query(
				ContactsContract.Contacts.CONTENT_URI, null, null, null, null);
		// 獲取聯系人總數
		int myContactAmount = cursor.getCount();
		progressDialog.setMax(myContactAmount);
		// 新建線程
		new Thread() {

			public void run() {

				int i = 0;
				while (cursor.moveToNext()) {
					i++;
					// 聯系人的ID
					String id = cursor.getString(cursor
							.getColumnIndex(ContactsContract.Contacts._ID));
					// 聯系人的名稱
					String name = cursor
							.getString(cursor
									.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
					// 聯系人的電話
					String number = "";

					// 聯系人是否有電話號碼
					int isHas = Integer
							.parseInt(cursor.getString(cursor
									.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER)));
					// 如果聯系人有電話，則遍歷他的所有電話號碼
					if (isHas > 0) {
						Cursor c = getContentResolver()
								.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
										null,
										ContactsContract.CommonDataKinds.Phone.CONTACT_ID
												+ " = " + id, null, null);
						while (c.moveToNext()) {
							number += c
									.getString(c
											.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER))
									+ "  ";
						}
						c.close();
					}
					myContactName.add(name);
					myContactNumber.add(number);

					Message msg = new Message();
					msg.arg1 = 1;
					msg.arg2 = i;
					handler.sendMessage(msg);

				}

				// 遍歷結束後，關閉進度條
				progressDialog.dismiss();
				cursor.close();

				Message msg = new Message();
				msg.arg1 = 2;
				handler.sendMessage(msg);

			}
		}.start();

	}

	class MyListAdapter extends BaseAdapter {

		public MyListAdapter(Context context) {
			myContext = context;
		}

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

		public Object getItem(int position) {
			// TODO Auto-generated method stub
			return position;
		}

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

		public View getView(int position, View convertView, ViewGroup parent) {
			// TODO Auto-generated method stub

			if (convertView == null) {
				viewHolder = new ViewHolder();

				convertView = LayoutInflater.from(myContext).inflate(
						R.layout.list, null);
				viewHolder.name = (TextView) convertView
						.findViewById(R.id.name);
				viewHolder.number = (TextView) convertView
						.findViewById(R.id.number);

				convertView.setTag(viewHolder);
			} else {
				viewHolder = (ViewHolder) convertView.getTag();
			}

			viewHolder.name.setText(myContactName.get(position));
			viewHolder.number.setText(myContactNumber.get(position));

			return convertView;
		}
	}

	private static class ViewHolder {
		TextView name;
		TextView number;

	}
}

布局文件：

list.xml

程序運行結果如下：