/// <summary>
/// 异步写入单行数据, 可多次执行, 之后执行 Close 方法关闭写入流.
/// </summary>
/// <typeparam name="T">要写入的数据对象类型</typeparam>
/// <param name="rowData">要写入的数据对象实例</param>
/// <param name="expression">处理对象实例,返回字段集合的方法.</param>
/// <returns>Task</returns>
public async Task WriteLineAsync <T>(T rowData, Func <T, List <string> > expression) where T : new()
{
if (this.CancelToken.IsCancellationRequested)
{
this.CancelToken.ThrowIfCancellationRequested();
}
if (rowData == null)
{
throw new ArgumentNullException("rowData");
}
if (expression == null)
{
throw new ArgumentNullException("expression");
}
//取转换后的行数据
var row = expression.Invoke(rowData);
//如果写入过一条数据, 则字段数固定. 如果再次写入的字段数不同, 报异常.
if (this.ColumnCount > 0 && this.ColumnCount != row.Count)
{
throw new ArgumentException("the rowData count must be equal to " + ColumnCount.ToString());
}
List <string> rows = this.SerializeRows(row);
await this.CsvStream.WriteLineAsync(rows[0]);
this.TotalRowCount++;
//设置字段数
if (this.ColumnCount == 0)
{
this.ColumnCount = row.Count;
}
//发送通知
if (Progress != null)
{
//如果取余数=0, 发送通知.
if (TotalRowCount % this.WriteProgressSize == 0L)
{
CsvWriteProgressInfo info = new CsvHelperAsync.CsvWriteProgressInfo();
info.CurrentRowCount = this.WriteProgressSize;
info.WirteRowCount = this.TotalRowCount;
Progress.Report(info);
}
}
}
/// <summary>
/// 关闭写入流, 并引发可能的最后一次通知事件.
/// </summary>
public void Close()
{
if (this.CsvStream != null)
{
this.CsvStream.Close();
this.CsvStream = null;
if (Progress != null)
{
//如果记录总数等于通知设定总数, 说明写入结束时刚好是要通知的数量, 但在 WriteLineAsync 方法中已经通知, 所以在这不再通知.
if (TotalRowCount != WriteProgressSize)
{
CsvWriteProgressInfo info = new CsvHelperAsync.CsvWriteProgressInfo();
info.CurrentRowCount = this.TotalRowCount % this.WriteProgressSize;
info.WirteRowCount = this.TotalRowCount;
Progress.Report(info);
}
}
}
}
