106 lines
3.1 KiB
C#
106 lines
3.1 KiB
C#
using System.Text;
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using MesETL.App.HostedServices.Abstractions;
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using Microsoft.Extensions.Logging;
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namespace MesETL.App.Services.ETL;
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/// <summary>
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/// CSV文件读取
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/// </summary>
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public class CsvReader : IDataReader
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{
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protected readonly string? FilePath;
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protected readonly Lazy<StreamReader> Reader;
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protected readonly ILogger? Logger;
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protected readonly string TableName;
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public DataRecord Current { get; protected set; } = null!;
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public string[] Headers { get; }
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public string? CurrentRaw { get; protected set; }
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public string Delimiter { get; }
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public char QuoteChar { get; }
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public CsvReader(Stream stream, string tableName, string[] headers, string delimiter = ",", char quoteChar = '"', ILogger? logger = null)
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: this(tableName, headers, delimiter, quoteChar, logger)
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{
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Reader = new Lazy<StreamReader>(() => new StreamReader(stream));
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}
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public CsvReader(string filePath, string tableName, string[] headers, string delimiter = ",", char quoteChar = '"', ILogger? logger = null)
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: this(tableName, headers, delimiter, quoteChar, logger)
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{
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var fs = File.OpenRead(filePath);
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FilePath = filePath;
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Reader = new Lazy<StreamReader>(() => new StreamReader(fs));
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}
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private CsvReader(string tableName, string[] headers, string delimiter = ",", char quoteChar = '"', ILogger? logger = null)
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{
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TableName = tableName;
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Headers = headers;
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Logger = logger;
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Delimiter = delimiter;
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QuoteChar = quoteChar;
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Reader = null!;
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}
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public virtual async ValueTask<bool> ReadAsync()
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{
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var str = await Reader.Value.ReadLineAsync();
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if (string.IsNullOrWhiteSpace(str))
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return false;
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CurrentRaw = str;
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var fields = ParseRow(str, QuoteChar, Delimiter);
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Current = new DataRecord(fields, TableName, Headers){RawField = str};
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return true;
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}
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public string[] ParseRow(ReadOnlySpan<char> source, char quoteChar, string delimiter)
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{
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var result = new List<string>();
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var index = -1;
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var current = new StringBuilder();
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var hasQuote = false;
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var hasSlash = false;
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while (index < source.Length - 1)
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{
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index++;
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if (hasSlash == false && source[index] == '\\')
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{
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hasSlash = true;
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current.Append('\\');
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continue;
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}
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if (hasSlash == false && source[index] == quoteChar)
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{
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hasQuote = !hasQuote;
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current.Append(source[index]);
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continue;
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}
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if (hasQuote == false && source[index] == delimiter[0])
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{
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result.Add(current.ToString());
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current.Clear();
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}
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else
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{
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current.Append(source[index]);
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}
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hasSlash = false;
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}
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result.Add(current.ToString());
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return result.ToArray();
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}
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public virtual void Dispose()
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{
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if(Reader.IsValueCreated)
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Reader.Value.Dispose();
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}
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} |