SqLite封转工具类

package com.cz.hello.utils;

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

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import com.cz.hello.model.CityInfo;

public class Db {
	private static final String	DB_NAME = "city.db";
	private static final int DB_VERSION = 1;
	private static Context mContext = null;

	private SQLiteDatabase mSQLiteDatabase	= null;
	private DatabaseHelper mDatabaseHelper	= null;
	
	private static final String	TABLE_CITY        = "table_city";   //城市表
	public static final String	KEY_ID           = "_id";         //数据id
	public static final String	KEY_CITY_NAME     = "city_name";    //城市名称
	public static final String	KEY_ADD_TIME     = "add_time";    //插入时间
	private static final String	TABLE_CITY_CREATE = "CREATE TABLE " + TABLE_CITY 
	    + " (" + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," 
	    + KEY_ADD_TIME  + " datetime default (datetime('now', 'localtime')),"
        + KEY_CITY_NAME + " TEXT)" ;
	
	
	private static class DatabaseHelper extends SQLiteOpenHelper
	{
		DatabaseHelper(Context context)
		{
			super(context, DB_NAME, null, DB_VERSION);
		}
		
		@Override
		public void onCreate(SQLiteDatabase db)
		{
			db.execSQL(TABLE_CITY_CREATE);
		}
		
		@Override
		public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
		{
			db.execSQL("DROP TABLE IF EXISTS notes");
			onCreate(db);
		}
	}
	
	public Db(Context context){
		mContext = context;
	}

	public void open() throws SQLException{
		mDatabaseHelper = new DatabaseHelper(mContext);
		mSQLiteDatabase = mDatabaseHelper.getWritableDatabase();
	}

	public void close(){
		mDatabaseHelper.close();
	}
	
	/**
	 * 插入一条城市数据
	 */
	public void insertCityData(String cityName)
	{
		if(Utils.isEmpty(cityName)){
			return;
		}
		open();
		ContentValues initialValues = new ContentValues();
		initialValues.put(KEY_CITY_NAME, cityName);

		Cursor cursor = mSQLiteDatabase.query(TABLE_CITY, null, KEY_CITY_NAME+"=?", new String[]{cityName}, null, null, null);
		if (cursor.moveToNext()) {
			mSQLiteDatabase.update(TABLE_CITY, initialValues, KEY_CITY_NAME+"=?", new String[]{cityName});
		}else{
			mSQLiteDatabase.insert(TABLE_CITY, null, initialValues);
		}
		
		cursor.close();
		
		close();
	}
	
	/**
	 * 获取所有城市列表数据
	 */
	public List<CityInfo> fetchAllCityData(){
		List<CityInfo> list = new ArrayList<CityInfo>();
		open();
		Cursor cursor = mSQLiteDatabase.query(TABLE_CITY, new String[] {
				KEY_ID, 
				KEY_CITY_NAME}, null, null, null, null, KEY_ADD_TIME+" desc");
		while (cursor.moveToNext()) {
			CityInfo city = new CityInfo();
			city.cityname = cursor.getString(cursor.getColumnIndex(KEY_CITY_NAME));
			city.id = cursor.getString(cursor.getColumnIndex(KEY_ID));
			list.add(city);
		}
		cursor.close();
		close();
		return list;
	}
	
	/**
	 * @author chenzheng
	 * @since 2014-7-26
	 * @Description: 根据id删除数据
	 * @throws
	 * @param id
	 * @return
	 * boolean
	 */
	public void deleteCityData(String id){
		open();
		mSQLiteDatabase.delete(TABLE_CITY, KEY_ID + "=" + id, null);  
		close();  
	}
}