.NET6之MiniAPI(特别篇)：.NET7 Preview1&2

在写.NET6 MiniAPI的时候，.NET7的新功能也在发展，这里就用特别篇把新加的特点分享给大家，本篇先说Preview1和2

技术点1

文件上传，demo如下：

var builder = WebApplication.CreateBuilder(args);var app = builder.Build();app.MapPost("/upload", async (IFormFile file) =>{    Console.WriteLine(file.FileName);    using var stream = System.IO.File.OpenWrite(file.FileName);    await file.CopyToAsync(stream);});app.MapPost("/uploads", async (IFormFileCollection files) =>{    foreach (var file in files)    {        Console.WriteLine(file.FileName);        using var stream = System.IO.File.OpenWrite(file.FileName);        await file.CopyToAsync(stream);    }});app.Run();

用postman测试，设置Content-Type为multipart/form-data，然后在Body中如下配置，在单文件上传时，key的值要与参数的名称相同。

多文件上传方式：

技术点2

同时还要以流的方式接收客户端数据：

using Microsoft.AspNetCore.Server.Kestrel.Core;var builder = WebApplication.CreateBuilder(args);//增加上传流数据的大小builder.Services.Configure<KestrelServerOptions>(options =>{    //默认是30M    options.Limits.MaxRequestBodySize = int.MaxValue;});var app = builder.Build();app.MapPost("/uploadbig", async (Stream body, CancellationToken cancellationToken) =>{    if (body.CanRead)    {        var setLength = 10240;        var readLength = 0;        var step = 1;        do        {            var arr = new byte[setLength];            readLength = await body.ReadAsync(arr, 0, arr.Length);            Console.WriteLine($"第{step++}次读取，流的长度：{readLength}");        } while (readLength >= setLength);    }    await Task.Delay(1);});app.Run();

用postman测试：

技术点3

在Preview2中，增加了同名参数，就是QueryString的参数名字可以相同，后台用数组接收，但数组类型只能是基础类型，或StringValues：

using Microsoft.Extensions.Primitives;using System.Text;var builder = WebApplication.CreateBuilder(args);var app = builder.Build();app.MapGet("/strs1", (StringValues strs) =>{    var backStr = new StringBuilder();    foreach (var str in strs)    {        backStr.Append($"str={str}，");    }    return backStr.ToString().TrimEnd('，');});app.MapGet("/strs2", (string[] strs) =>{    var backStr = new StringBuilder();    foreach (var str in strs)    {        backStr.Append($"str={str}，");    }    return backStr.ToString().TrimEnd('，'); });app.Run();

用postman测试：

技术点4

如果自定义类型怎么办，系统也提供了一个转换的方式，在类型中实现TryParse方法，达到类型转换的效果：

var builder = WebApplication.CreateBuilder(args);var app = builder.Build();app.MapGet("/points", (Point[] points) =>{    var backPoint = new StringBuilder();    foreach (var point in points)    {        backPoint.AppendLine(point.ToString());    }    return backPoint.ToString();});app.Run();//定义point类型record Point{    public double X { get; set; }    public double Y { get; set; }    public static bool TryParse(string? pointStr, out Point? point)    {        if (pointStr is null)        {            point = null;            return false;        }        point = new Point        {            X = double.Parse(pointStr.Split(',')[0]),            Y = double.Parse(pointStr.Split(',')[1])        };        return true;    }}

用postman测试：