DatabaseHelper.java

package com.jiuqi.njt.db;

import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.util.Log;

import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
import com.j256.ormlite.dao.Dao;
import com.j256.ormlite.support.ConnectionSource;
import com.j256.ormlite.table.TableUtils;
import com.jiuqi.njt.data.AdminAreaBeanLocal;
import com.jiuqi.njt.data.DataDictionaryBeanLocal;
import com.jiuqi.njt.data.KindsOfCarBeanLocal;
import com.jiuqi.njt.data.WorkTaskBeanLocal;

public class DatabaseHelper extends OrmLiteSqliteOpenHelper {

	private static final String TABLE_NAME = "njtfb.db";
	private static final int VERSION = 3;

	private Map<String, Dao> daos = new HashMap<String, Dao>();

	private DatabaseHelper(Context context)
	{
		super(context, TABLE_NAME, null, VERSION);
	}

	@Override
	public void onCreate(SQLiteDatabase database,
			ConnectionSource arg1)
	{
		try
		{
			 
			TableUtils.createTableIfNotExists(arg1, WorkTaskBeanLocal.class);
			TableUtils.createTableIfNotExists(arg1, AdminAreaBeanLocal.class);
			TableUtils.createTableIfNotExists(arg1, DataDictionaryBeanLocal.class);
			TableUtils.createTableIfNotExists(arg1, KindsOfCarBeanLocal.class);
		} catch (SQLException e)
		{
			e.printStackTrace();
		}
	}

	@Override
	public void onUpgrade(SQLiteDatabase database,
			ConnectionSource arg1, int oldVersion, int newVersion)
	{
		try
		{
			TableUtils.dropTable(arg1, WorkTaskBeanLocal.class, true);
			TableUtils.createTable(arg1, WorkTaskBeanLocal.class);
			TableUtils.dropTable(arg1, AdminAreaBeanLocal.class, true);
			TableUtils.createTable(arg1, AdminAreaBeanLocal.class);
			TableUtils.dropTable(arg1, DataDictionaryBeanLocal.class, true);
			TableUtils.createTable(arg1, DataDictionaryBeanLocal.class);
			
			TableUtils.dropTable(arg1, KindsOfCarBeanLocal.class, true);
			TableUtils.createTable(arg1, KindsOfCarBeanLocal.class);
		} catch (SQLException e)
		{
			e.printStackTrace();
		}
	}

	private static DatabaseHelper instance;

	/**
	 * 单例获取该Helper
	 * 
	 * @param context
	 * @return
	 */
	public static synchronized DatabaseHelper getHelper(Context context)
	{
		context = context.getApplicationContext();
		if (instance == null)
		{
			synchronized (DatabaseHelper.class)
			{
				if (instance == null)
					instance = new DatabaseHelper(context);
			}
		}

		return instance;
	}

	public synchronized Dao getDao(Class clazz) throws SQLException
	{
		Dao dao = null;
		String className = clazz.getSimpleName();

		if (daos.containsKey(className))
		{
			dao = daos.get(className);
		}
		if (dao == null)
		{
			dao = super.getDao(clazz);
			daos.put(className, dao);
		}
		return dao;
	}

	/**
	 * 释放资源
	 */
	@Override
	public void close()
	{
		super.close();

		for (String key : daos.keySet())
		{
			Dao dao = daos.get(key);
			dao = null;
		}
	}

}