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5.14 非同步方法

以工作為基礎的非同步模式 (TAP) 是 .NET Framework 中用於非同步的模式。它基於 System.Threading.Tasks 命名空間中的 Task 和 Task<TResult> 類型，這些類型用於表示任意的非同步作業。

Async-Await 是為了使用 TAP 而引入的新關鍵字。Async 修飾詞 用於指定方法、Lambda 運算式或匿名方法是非同步的。Await 運算子會套用至非同步方法中的工作，以暫停方法的執行，直到等待的工作完成。

需求

  • Async-Await 支援需要 .NET Framework 4.5 或更新版本

  • TAP 支援需要 .NET Framework 4.0 或更新版本

  • MySQL Connector/NET 6.9 或更新版本

方法

以下方法可以搭配 TAP 或 Async-Await 使用。

  • 命名空間 MySql.Data.Entity

    • 類別 EFMySqlCommand

      • Task PrepareAsync()

      • Task PrepareAsync(CancellationToken)

  • 命名空間 MySql.Data

    • 類別 MySqlBulkLoader

      • Task<int> LoadAsync()

      • Task<int> LoadAsync(CancellationToken

    • 類別 MySqlConnection

      • Task<MySqlTransaction> BeginTransactionAsync()

      • Task<MySqlTransaction> BeginTransactionAsync (CancellationToken)

      • Task<MySqlTransaction> BeginTransactionAsync(IsolationLevel)

      • Task<MySqlTransaction> BeginTransactionAsync (IsolationLevel , CancellationToken)

      • Task ChangeDatabaseAsync(string)

      • Task ChangeDatabaseAsync(string, CancellationToken)

      • Task CloseAsync()

      • Task CloseAsync(CancellationToken)

      • Task ClearPoolAsync(MySqlConnection)

      • Task ClearPoolAsync(MySqlConnection, CancellationToken)

      • Task ClearAllPoolsAsync()

      • Task ClearAllPoolsAsync(CancellationToken)

      • Task<MySqlSchemaCollection> GetSchemaCollection(string, string[])

      • Task<MySqlSchemaCollection> GetSchemaCollection(string, string[], CancellationToken)

    • 類別 MySqlDataAdapter

      • Task<int> FillAsync(DataSet)

      • Task<int> FillAsync(DataSet, CancellationToken)

      • Task<int> FillAsync(DataTable)

      • Task<int> FillAsync(DataTable, CancellationToken)

      • Task<int> FillAsync(DataSet, string)

      • Task<int> FillAsync(DataSet, string, CancellationToken)

      • Task<int> FillAsync(DataTable, IDataReader)

      • Task<int> FillAsync(DataTable, IDataReader, CancellationToken)

      • Task<int> FillAsync(DataTable, IDbCommand, CommandBehavior)

      • Task<int> FillAsync(DataTable, IDbCommand, CommandBehavior, CancellationToken)

      • Task<int> FillAsync(int, int, params DataTable[])

      • Task<int> FillAsync(int, int, params DataTable[], CancellationToken)

      • Task<int> FillAsync(DataSet, int, int, string)

      • Task<int> FillAsync(DataSet, int, int, string, CancellationToken)

      • Task<int> FillAsync(DataSet, string, IDataReader, int, int)

      • Task<int> FillAsync(DataSet, string, IDataReader, int, int, CancellationToken)

      • Task<int> FillAsync(DataTable[], int, int, IDbCommand, CommandBehavior)

      • Task<int> FillAsync(DataTable[], int, int, IDbCommand, CommandBehavior, CancellationToken)

      • Task<int> FillAsync(DataSet, int, int, string, IDbCommand, CommandBehavior)

      • Task<int> FillAsync(DataSet, int, int, string, IDbCommand, CommandBehavior, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string, IDataReader)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string, IDataReader, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, IDbCommand, string, CommandBehavior)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, IDbCommand, string, CommandBehavior, CancellationToken)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, CancellationToken)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDataReader)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDataReader, CancellationToken)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDbCommand, CommandBehavior)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDbCommand, CommandBehavior, CancellationToken)

      • Task<int> UpdateAsync(DataRow[])

      • Task<int> UpdateAsync(DataRow[], CancellationToken)

      • Task<int> UpdateAsync(DataSet)

      • Task<int> UpdateAsync(DataSet, CancellationToken)

      • Task<int> UpdateAsync(DataTable)

      • Task<int> UpdateAsync(DataTable, CancellationToken)

      • Task<int> UpdateAsync(DataRow[], DataTableMapping, CancellationToken)

      • Task<int> UpdateAsync(DataSet, string)

      • Task<int> UpdateAsync(DataSet, string, CancellationToken)

    • 類別 MySqlHelper

      • Task<DataRow> ExecuteDataRowAsync(string, string, params MySqlParameter[])

      • Task<DataRow> ExecuteDataRowAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(string, string, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<DataSet> ExecuteDatasetAsync(string, string)

      • Task<DataSet> ExecuteDatasetAsync(string, string, CancellationToken)

      • Task<DataSet> ExecuteDatasetAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string)

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string, CancellationToken)

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

      • Task UpdateDataSetAsync(string, string, DataSet, string)

      • Task UpdateDataSetAsync(string, string, DataSet, string, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, MySqlTransaction, string, MySqlParameter[], bool)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, MySqlTransaction, string, MySqlParameter[], bool, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string)

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string, params MySqlParameter[])

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(string, string)

      • Task<object> ExecuteScalarAsync(string, string, CancellationToken)

      • Task<object> ExecuteScalarAsync(string, string, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(MySqlConnection, string)

      • Task<object> ExecuteScalarAsync(MySqlConnection, string, CancellationToken)

      • Task<object> ExecuteScalarAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

    • 類別 MySqlScript

      • Task<int> ExecuteAsync()

      • Task<int> ExecuteAsync(CancellationToken)

除了上面列出的方法外，以下是繼承自 .NET Framework 的方法

  • 命名空間 MySql.Data.Entity

    • 類別 EFMySqlCommand

      • Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehaviour, CancellationToken)

      • Task<int> ExecuteNonQueryAsync()

      • Task<int> ExecuteNonQueryAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync()

      • Task<DbDataReader> ExecuteReaderAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour, CancellationToken)

      • Task<object> ExecuteScalarAsync()

      • Task<object> ExecuteScalarAsync(CancellationToken)

  • 命名空間 MySql.Data

    • 類別 MySqlCommand

      • Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehaviour, CancellationToken)

      • Task<int> ExecuteNonQueryAsync()

      • Task<int> ExecuteNonQueryAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync()

      • Task<DbDataReader> ExecuteReaderAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour, CancellationToken)

      • Task<object> ExecuteScalarAsync()

      • Task<object> ExecuteScalarAsync(CancellationToken)

    • 類別 MySqlConnection

      • Task OpenAsync()

      • Task OpenAsync(CancellationToken)

    • 類別 MySqlDataReader

      • Task<T> GetFieldValueAsync<T>(int)

      • Task<T> GetFieldValueAsync<T>(int, CancellationToken)

      • Task<bool> IsDBNullAsync(int)

      • Task<bool> IsDBNullAsync(int, CancellationToken)

      • Task<bool> NextResultAsync()

      • Task<bool> NextResultAsync(CancellationToken)

      • Task<bool> ReadAsync()

      • Task<bool> ReadAsync(CancellationToken)

範例

以下 C# 程式碼範例示範如何使用非同步方法

在此範例中，方法具有 async 修飾詞，因為所進行的 await 呼叫適用於 LoadAsync 方法。此方法會傳回一個 Task 物件，其中包含關於等待方法結果的資訊。傳回 Task 就像有一個 void 方法，但是如果您的方法不是像事件一樣的頂層存取方法，則不應使用 async void。

public async Task BulkLoadAsync()
{
  MySqlConnection myConn = new MySqlConnection("MyConnectionString");
  MySqlBulkLoader loader = new MySqlBulkLoader(myConn);

  loader.TableName       = "BulkLoadTest";
  loader.FileName        = @"c:\MyPath\MyFile.txt";
  loader.Timeout         = 0;

  var result             = await loader.LoadAsync();
}

在此範例中，「async void」方法與「await」一起用於 ExecuteNonQueryAsync 方法，以對應於按鈕的 onclick 事件。這就是為什麼該方法不傳回 Task 的原因。

private async void myButton_Click()
{
  MySqlConnection myConn = new MySqlConnection("MyConnectionString");
  MySqlCommand proc      = new MySqlCommand("MyAsyncSpTest", myConn);

  proc.CommandType       = CommandType.StoredProcedure;

  int result             = await proc.ExecuteNonQueryAsync();
}

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