Stream流应用

　　对上传zip压缩文本文件解析，引用第三方包SharpZipLib，写了一个静态扩展类。主要是对Stream流的基本操作方便下次翻看，代码如下：

using ICSharpCode.SharpZipLib.Zip;
using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Threading.Tasks;

namespace Extensions
{
    /// <summary>
    /// Zip辅助类
    /// </summary>
    public static class ZipHelperExtension
    {
        /// <summary>
        /// 解压单zip压缩文件
        /// </summary>
        /// <param name="sourceFile">压缩文件</param>
        /// <param name="contentHandle">文本内容处理</param>
        /// <returns>压缩的所有文件处理结果</returns>
        public static async Task<(IList<T> modelList, string errMessage)> UnZipFileAsync<T>(IFormFile sourceFile,
            Func<string, Task<T>> contentHandle) where T : class
        {
            var err = string.Empty;
            var modelList = new List<T>();
            try
            {
                await using ZipInputStream zipIn = new(sourceFile.OpenReadStream());

                var models = await UnZipAsync(zipIn, contentHandle);
                modelList.AddRange(models);
            }
            catch (Exception ex)
            {
                err = $"错误信息=>{sourceFile.Name}：{ex.Message};";
            }

            return (modelList, err);
        }

        /// <summary>
        /// 批量解压zip压缩文件
        /// </summary>
        /// <param name="sourceFiles">压缩文件</param>
        /// <param name="contentHandle">文本内容处理</param>
        /// <returns>压缩的所有文件处理结果</returns>
        public static async Task<(IList<T> list, string err)> UnZipFilesAsync<T>(IFormFileCollection sourceFiles,
            Func<string, Task<T>> contentHandle) where T : class
        {
            var err = string.Empty;
            var list = new List<T>();
            foreach (var sourceFile in sourceFiles)
            {
                var (modelList, errMessage) = await UnZipFileAsync(sourceFile, contentHandle);
                list.AddRange(modelList);
                err += errMessage;
            }

            return (list, err);
        }

        /// <summary>
        /// 处理zip压缩文件内容
        /// </summary>
        /// <param name="zipIn">压缩文件流</param>
        /// <param name="contentHandle">文本内容处理</param>
        /// <returns>压缩的所有文件处理结果集合</returns>
        public static async Task<IEnumerable<T>> UnZipAsync<T>(ZipInputStream zipIn, 
            Func<string, Task<T>> contentHandle) where T : class
        {
            var list = new List<T>();
            while (zipIn.GetNextEntry() != null)
            {
                Stream stream = new MemoryStream();
                await using var bos = new BinaryWriter(stream, Encoding.Default, leaveOpen: false);

                var bytes = new byte[1024];
                while (true)
                {
                    var len = await zipIn.ReadAsync(bytes);
                    if (len <= 0)
                    {
                        break;
                    }

                    bos.Write(bytes, 0, len);
                    bos.Flush();
                }

                if (stream.Length == 0) continue;//过滤文件夹
                stream.Position = 0;
                var content = await GetTextStreamContentAsync(stream);
                var model = await contentHandle(content);
                list.Add(model);
            }

            return list;
        }

        /// <summary>
        /// 获取文本流
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>文本流</returns>
        public static async Task<Stream> GetStreamAsync(this string str)
        {
            var stream = new MemoryStream();
            //leaveOpen：true使StreamWriter释放而stream不会释放
            await using var writer = new StreamWriter(stream, leaveOpen: true);

            await writer.WriteAsync(str);
            await writer.FlushAsync();

            stream.Position = 0;
            return stream;
        }

        /// <summary>
        /// 获取文本流内容
        /// </summary>
        /// <param name="textStream">文本流</param>
        /// <returns>文本流内容</returns>
        public static async Task<string> GetTextStreamContentAsync(Stream textStream)
        {
            using var reader = new StreamReader(textStream);
            return await reader.ReadToEndAsync();
        }
    }
}

　　

　　上传文件测试一下用法：

        /// <summary>
        /// 解压zip测试
        /// </summary>
        /// <param name="zipFile">压缩文件</param>
        /// <returns></returns>
        [HttpPost("unzip-test")]
        //这个注意IFormFile,IFormFileCollection类型前面不需要直接加[FromForm]特性，否者swagger不支持上传文件
        //可以将表单所有参数(包括文件IFormFile,IFormFileCollection)封装一个参数对象，前面加[FromForm]特性
        public async Task UnzipTest(IFormFile zipFile)
        {
            var (persons, errMessage) = await ZipHelperExtension.UnZipFileAsync(zipFile,
                async content =>
            {
                var person = JsonConvert.DeserializeObject<Person>(content);
                person?.Pets.Add(new Pet() { Name = "小猪", Age = 5 });
                person?.Pets.ForEach(p => p.Master = person);
                return await Task.FromResult(person);
            });
            _logger.LogInformation(string.Join("\n", persons));
        }

 

　　

结果：