sqlite helper

//-------------------------------------------------------------------------- 
//  
//  Copyright (c) BUSHUOSX.  All rights reserved.  
//  
//  File: SqliteDbManager.cs 
//
//  Version:1.0.0.0
//
//  Datetime:
// 
//---------------------------------------------------------------------------
/*
 * 
 * 修改时间：20140829 211000
 * 
 * 
 * 
 * 
 */

using System;
using System.Configuration;
using System.Data.SQLite;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;

namespace BUSHUOSX.Helper
{

    public sealed class SqliteDbManager
    {
        /// <summary>
        /// 获取连接字符串中某项的值
        /// </summary>
        /// <param name="connectionString">连接字符串</param>
        /// <param name="itemName">项目</param>
        /// <returns>项目值</returns>
        private static string GetItemValueFromConnectionString(string connectionString, string itemName)
        {
            if (!connectionString.EndsWith(";"))
                connectionString += ";";

            // \s* 匹配0个或多个空白字符
            // .*? 匹配0个或多个除 "\n" 之外的任何字符(?指尽可能少重复)
            string regexStr = itemName + @"\s*=\s*(?<key>.*?);";
            Regex r = new Regex(regexStr, RegexOptions.IgnoreCase);
            Match mc = r.Match(connectionString);
            return mc.Groups["key"].Value;
        }

        /// <summary>
        /// 创建System.Data.Sqlite数据库样式的连接字符串
        /// </summary>
        /// <param name="dbName">数据库名</param>
        /// <param name="dbFileExtName">数据库文件扩展名</param>
        /// <param name="dbPassword">数据库密码</param>
        /// <param name="dbDirectory">数据库目录路径</param>
        /// <returns>dbName为空时，返回空</returns>
        public static string GenerateSqliteConnectionString(string dbFileName, string dbPassword = "", string dbDirectory = "")
        {
            if (string.IsNullOrEmpty(dbFileName))
            {
                return "";
            }

            StringBuilder sb = new StringBuilder("Data Source=");
            if (!string.IsNullOrEmpty(dbDirectory))
            {
                sb.Append(dbDirectory);
                if (!dbDirectory.EndsWith("\\"))
                    sb.Append(‘\\‘);
            }

            sb.Append(dbFileName).Append(‘;‘);

            if (!string.IsNullOrEmpty(dbPassword))
                sb.AppendFormat("Password={0};", dbPassword);

            return sb.ToString();
        }

        /// <summary>
        /// 尝试用sqliteConnectionString打开已存在的数据库，或者用sqliteConnectionString创建新的数据库
        /// </summary>
        /// <param name="dbFileName"></param>
        /// <param name="dbPassword"></param>
        /// <returns></returns>
        public static bool OpenOrCreateSqliteDateBase(string dbFileName, string dbPassword)
        {
            return OpenOrCreateSqliteDateBase(GenerateSqliteConnectionString(dbFileName, dbPassword));
        }

        /// <summary>
        /// 尝试用sqliteConnectionString打开已存在的数据库，或者用sqliteConnectionString创建新的数据库
        /// </summary>
        /// <param name="sqliteConnectionString"></param>
        /// <returns></returns>
        public static bool OpenOrCreateSqliteDateBase(string sqliteConnectionString)
        {
            string dbFileName = GetItemValueFromConnectionString(sqliteConnectionString, "Data Source");
            string dbPassword = GetItemValueFromConnectionString(sqliteConnectionString, "Password");
            if (string.IsNullOrEmpty(dbFileName))
            {
                return false;
            }

            try
            {
                if (!File.Exists(dbFileName))
                {
                    //创建目录
                    var parent = Directory.GetParent(dbFileName);
                    if (null != parent && !parent.Exists)
                    {
                        Directory.CreateDirectory(parent.FullName);
                    }
                    //var fs = File.Create(dbName);
                    //fs.Close();

                    //创建数据库
                    SQLiteConnection sqlconn = new SQLiteConnection("Data Source=" + dbFileName);
                    sqlconn.Open();
                    //设置密码
                    if (!string.IsNullOrEmpty(dbPassword))
                        sqlconn.ChangePassword(dbPassword);
                    sqlconn.Close();

                    return true;
                }
            }
            catch (SQLiteException e)
            {
                return false;
            }
            catch (Exception e)
            {
                return false;
            }

            try
            {
                //尝试打开数据库
                SQLiteConnection sqlconn = new SQLiteConnection(sqliteConnectionString);
                sqlconn.Open();
                sqlconn.Close();
            }
            catch (SQLiteException e)
            {
                return false;
            }

            return true;
        }

        public static bool TableExists(string sqliteConnectionString, string tableName)
        {
            bool result = false;
            SQLiteConnection sqlconn = new SQLiteConnection(sqliteConnectionString);
            try
            {
                SQLiteCommand scmd = new SQLiteCommand(sqlconn);
                scmd.CommandText = string.Format(@"select count(*) from sqlite_master where type=‘table‘ and name=‘{0}‘", tableName);

                //打开数据库
                sqlconn.Open();

                var v = scmd.ExecuteScalar();
                if (1 == Convert.ToInt32(v))
                {
                    result = true;
                }
            }
            catch (Exception)
            {
                //throw;
            }
            sqlconn.Close();
            return result;
        }

        public static bool DropTable(string sqliteConnectionString, string tableName)
        {
            return null != ExecuteNonQuery(sqliteConnectionString, string.Format("drop table if exists {0}", tableName));
        }

        public static bool RenameTable(string sqliteConnectionString, string oldTableName, string newTableName)
        {
            return null != ExecuteNonQuery(sqliteConnectionString, string.Format("alter table {0} rename to {1}", oldTableName, newTableName));
        }

        /// <summary>
        /// 执行sql命令
        /// </summary>
        /// <param name="sqliteConnectionString"></param>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static object ExecuteNonQuery(string sqliteConnectionString, string sql)
        {
            object result = null;

            SQLiteConnection sqlconn = new SQLiteConnection(sqliteConnectionString);
            try
            {
                //打开数据库
                sqlconn.Open();

                SQLiteCommand scmd = new SQLiteCommand(sqlconn);
                scmd.CommandText = sql;
                result = scmd.ExecuteNonQuery();
            }
            catch (Exception e)
            {
                //throw;
            }
            sqlconn.Close();

            return result;
        }
    }
}