apewer-dotnet/Apewer/Source/DbClient.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Text;

namespace Apewer.Source
{

    /// <summary></summary>
    abstract class DbClient
    {

        /// <summary></summary>
        public virtual Logger Logger { get; set; }

        #region Connection

        DbConnection _conn = null;
        string _str = null;

        /// <summary></summary>
        public Timeout Timeout { get; set; }

        /// <summary></summary>
        public DbConnection Connection { get => _conn; }

        /// <summary></summary>
        public bool Online { get => _conn == null ? false : (_conn.State == ConnectionState.Open); }

        /// <summary>连接字符串。</summary>
        public string ConnectionString { get => _str; }

        /// <summary></summary>
        public virtual string Connect()
        {
            if (_conn == null)
            {
                _str = GetConnectionString();
                _conn = NewConnection();
                _conn.ConnectionString = _str;
            }
            else
            {
                if (_conn.State == ConnectionState.Open) return null;
            }

            try
            {
                _conn.Open();
                switch (_conn.State)
                {
                    case ConnectionState.Open: return null;
                    default: return $"连接失败，当前处于 {_conn.State} 状态。";
                }
            }
            catch (Exception ex)
            {
                Logger.Error(this, "Connect", ex, _conn.ConnectionString);
                Close();
                return ex.Message;
            }
        }

        /// <summary></summary>
        public void Close()
        {
            if (_conn != null)
            {
                if (_transaction != null)
                {
                    if (_autocommit) Commit();
                    else Rollback();
                }
                _conn.Close();
                _conn.Dispose();
                _conn = null;
            }
        }

        /// <summary></summary>
        public void Dispose() { Close(); }

        #endregion

        #region Transaction

        private DbTransaction _transaction = null;
        private bool _autocommit = false;

        /// <summary>启动事务。</summary>
        public string Begin(bool commit = true) => Begin(commit, null);

        /// <summary>启动事务。</summary>
        public string Begin(bool commit, Class<System.Data.IsolationLevel> isolation)
        {
            if (Connect() != null) return "未连接。";
            if (_transaction != null) return "存在已启动的事务，无法再次启动。";
            try
            {
                _transaction = isolation ? _conn.BeginTransaction(isolation.Value) : _conn.BeginTransaction();
                _autocommit = commit;
                return null;
            }
            catch (Exception ex)
            {
                Logger.Error(this, "Commit", ex.Message());
                return ex.Message();
            }
        }

        /// <summary>提交事务。</summary>
        public string Commit()
        {
            if (_transaction == null) return "事务不存在。";
            try
            {
                _transaction.Commit();
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                return null;
            }
            catch (Exception ex)
            {
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                Logger.Error(this, "Commit", ex.Message());
                return ex.Message();
            }
        }

        /// <summary>从挂起状态回滚事务。</summary>
        public string Rollback()
        {
            if (_transaction == null) return "事务不存在。";
            try
            {
                _transaction.Rollback();
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                return null;
            }
            catch (Exception ex)
            {
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                Logger.Error(this, "Rollback", ex.Message());
                return ex.Message();
            }
        }

        #endregion

        #region ADO

        /// <summary>查询。</summary>
        public IQuery Query(string sql) => Query(sql, null);

        /// <summary>查询。</summary>
        public IQuery Query(string sql, IEnumerable<IDataParameter> parameters)
        {
            if (TextUtility.IsBlank(sql)) return new Query(false, "语句无效。");
            var connected = Connect();
            if (connected.NotEmpty()) return new Query(false, connected);

            try
            {
                using (var command = NewCommand())
                {
                    command.Connection = _conn;
                    if (Timeout != null) command.CommandTimeout = Timeout.Query;
                    command.CommandText = sql;
                    if (parameters != null)
                    {
                        foreach (var parameter in parameters)
                        {
                            if (parameter != null) command.Parameters.Add(parameter);
                        }
                    }
                    using (var ds = new DataSet())
                    {
                        using (var da = NewDataAdapter(sql))
                        {
                            var name = "table_" + Guid.NewGuid().ToString("n");
                            da.Fill(ds, name);
                            var table = ds.Tables[name];
                            return new Query(table, true);
                        }
                    }
                }
            }
            catch (Exception exception)
            {
                Logger.Error(this, "Query", exception, sql);
                return new Query(exception);
            }
        }

        /// <summary>执行。</summary>
        public IExecute Execute(string sql) => Execute(sql, null);

        /// <summary>执行单条 Transact-SQL 语句，并加入参数。</summary>
        public IExecute Execute(string sql, IEnumerable<IDataParameter> parameters)
        {
            if (TextUtility.IsBlank(sql)) return Example.InvalidExecuteStatement;

            var connected = Connect();
            if (connected.NotEmpty()) return new Execute(false, connected);

            var inTransaction = _transaction != null;
            if (!inTransaction) Begin();
            try
            {
                using (var command = NewCommand())
                {
                    command.Connection = _conn;
                    command.Transaction = (DbTransaction)_transaction;
                    if (Timeout != null) command.CommandTimeout = Timeout.Execute;
                    command.CommandText = sql;
                    if (parameters != null)
                    {
                        foreach (var parameter in parameters)
                        {
                            if (parameter != null) command.Parameters.Add(parameter);
                        }
                    }
                    var rows = command.ExecuteNonQuery();
                    if (!inTransaction) Commit(); // todo 此处应该检查事务提交产生的错误。
                    return new Execute(true, rows);
                }
            }
            catch (Exception exception)
            {
                Logger.Error(this, "Execute", exception, sql);
                if (!inTransaction) Rollback();
                return new Execute(exception);
            }
        }

        #endregion

        #region ORM - Query

        /// <summary>查询记录。</summary>
        /// <param name="model">记录模型。</param>
        /// <param name="sql">SQL 语句。</param>
        public Result<object[]> Query(Type model, string sql)
        {
            if (_conn == null) return new Result<object[]>("连接无效。");
            if (model == null) return new Result<object[]>("数据模型类型无效。");
            if (string.IsNullOrEmpty(sql)) return new Result<object[]>("SQL 语句无效。");

            var query = Query(sql);
            var result = null as Result<object[]>;

            if (query.Success)
            {
                try
                {
                    var array = OrmHelper.Fill(query, model);
                    result = new Result<object[]>(array);
                }
                catch (Exception ex)
                {
                    result = new Result<object[]>(ex);
                }
            }
            else
            {
                result = new Result<object[]>(query.Message);
            }

            query.Dispose();
            return result;
        }

        /// <summary></summary>
        public Result<T[]> Query<T>(string sql) where T : class, new()
        {
            var query = Query(sql);
            if (!query.Success) return new Result<T[]>(query.Message);
            var records = query.Fill<T>();
            query.Dispose();

            var result = new Result<T[]>(records);
            return result;
        }

        #endregion

        #region Static

        /// <summary>对文本转义，符合 SQL 安全性。可根据字段类型限制 UTF-8 字节数，默认为 0 时不限制字节数。</summary>
        protected static string Escape(string text, int bytes = 0)
        {
            if (text.IsEmpty()) return "";

            var t = text ?? "";
            t = t.Replace("\\", "\\\\");
            t = t.Replace("'", "\\'");
            t = t.Replace("\n", "\\n");
            t = t.Replace("\r", "\\r");
            t = t.Replace("\b", "\\b");
            t = t.Replace("\t", "\\t");
            t = t.Replace("\f", "\\f");

            if (bytes > 5)
            {
                if (t.Bytes(Encoding.UTF8).Length > bytes)
                {
                    while (true)
                    {
                        t = t.Substring(0, t.Length - 1);
                        if (t.Bytes(Encoding.UTF8).Length <= (bytes - 4)) break;
                    }
                    t = t + " ...";
                }
            }

            return t;
        }

        #endregion

        /// <summary></summary>
        protected abstract string GetConnectionString();

        /// <summary></summary>
        protected abstract DbConnection NewConnection();

        /// <summary></summary>
        protected abstract DbDataAdapter NewDataAdapter(string sql);

        /// <summary></summary>
        protected abstract DbCommand NewCommand();

    }

}