.NET 6新增的20个API介绍

DateOnly & TimeOnly

.NET 6 引入了两种期待已久的类型 - DateOnly 和 TimeOnly, 它们分别代表DateTime的日期和时间部分。

DateOnly dateOnly = new(2021, 9, 25); Console.WriteLine(dateOnly); TimeOnly timeOnly = new(19, 0, 0); Console.WriteLine(timeOnly); DateOnly dateOnlyFromDate = DateOnly.FromDateTime(DateTime.Now); Console.WriteLine(dateOnlyFromDate); TimeOnly timeOnlyFromDate = TimeOnly.FromDateTime(DateTime.Now); Console.WriteLine(timeOnlyFromDate);

Parallel.ForEachAsync

它可以控制多个异步任务的并行度。

var userHandlers = new[] { "users/okyrylchuk", "users/jaredpar", "users/davidfowl" }; using HttpClient client = new() { BaseAddress = new Uri("https://api.github.com"), }; client.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("DotNet", "6")); ParallelOptions options = new() { MaxDegreeOfParallelism = 3 }; await Parallel.ForEachAsync(userHandlers, options, async (uri, token) => { var user = await client.GetFromJsonAsync(uri, token); Console.WriteLine($"Name: {user.Name}\nBio: {user.Bio}\n"); }); public class GitHubUser { public string Name { get; set; } public string Bio { get; set; } } // Output: // Name: David Fowler // Bio: Partner Software Architect at Microsoft on the ASP.NET team, Creator of SignalR // // Name: Oleg Kyrylchuk // Bio: Software developer | Dotnet | C# | Azure // // Name: Jared Parsons // Bio: Developer on the C# compiler

ArgumentNullException.ThrowIfNull()

ArgumentNullException 的小改进, 在抛出异常之前不需要在每个方法中检查 null, 现在只需要写一行, 和 response.EnsureSuccessStatusCode(); 类似。

ExampleMethod(null); void ExampleMethod(object param) { ArgumentNullException.ThrowIfNull(param); // Do something }

PriorityQueue

.NET 6 新增的数据结构, PriorityQueue, 队列每个元素都有一个关联的优先级，它决定了出队顺序, 编号小的元素优先出列。

PriorityQueue priorityQueue = new(); priorityQueue.Enqueue("Second", 2); priorityQueue.Enqueue("Fourth", 4); priorityQueue.Enqueue("Third 1", 3); priorityQueue.Enqueue("Third 2", 3); priorityQueue.Enqueue("First", 1); while (priorityQueue.Count > 0) { string item = priorityQueue.Dequeue(); Console.WriteLine(item); } // Output: // First // Second // Third 2 // Third 1 // Fourth

RandomAccess

提供基于偏移量的 API，用于以线程安全的方式读取和写入文件。

using SafeFileHandle handle = File.OpenHandle("file.txt", access: FileAccess.ReadWrite); // Write to file byte[] strBytes = Encoding.UTF8.GetBytes("Hello world"); ReadOnlyMemory buffer1 = new(strBytes); await RandomAccess.WriteAsync(handle, buffer1, 0); // Get file length long length = RandomAccess.GetLength(handle); // Read from file Memory buffer2 = new(new byte[length]); await RandomAccess.ReadAsync(handle, buffer2, 0); string content = Encoding.UTF8.GetString(buffer2.ToArray()); Console.WriteLine(content); // Hello world

PeriodicTimer

认识一个完全异步的“PeriodicTimer”, 更适合在异步场景中使用, 它有一个方法 WaitForNextTickAsync。

// One constructor: public PeriodicTimer(TimeSpan period) using PeriodicTimer timer = new(TimeSpan.FromSeconds(1)); while (await timer.WaitForNextTickAsync()) { Console.WriteLine(DateTime.UtcNow); } // Output: // 13 - Oct - 21 19:58:05 PM // 13 - Oct - 21 19:58:06 PM // 13 - Oct - 21 19:58:07 PM // 13 - Oct - 21 19:58:08 PM // 13 - Oct - 21 19:58:09 PM // 13 - Oct - 21 19:58:10 PM // 13 - Oct - 21 19:58:11 PM // 13 - Oct - 21 19:58:12 PM // ...

Metrics API

.NET 6 实现了 OpenTelemetry Metrics API 规范, 内置了指标API, 通过 Meter 类创建下面的指标

Counter Histogram ObservableCounter ObservableGauge

使用的方法如下：

var builder = WebApplication.CreateBuilder(args); var app = builder.Build(); // Create Meter var meter = new Meter("MetricsApp", "v1.0"); // Create counter Counter counter = meter.CreateCounter("Requests"); app.Use((context, next) => { // Record the value of measurement counter.Add(1); return next(context); }); app.MapGet("/", () => "Hello World"); StartMeterListener(); app.Run(); // Create and start Meter Listener void StartMeterListener() { var listener = new MeterListener(); listener.InstrumentPublished = (instrument, meterListener) => { if (instrument.Name == "Requests" && instrument.Meter.Name == "MetricsApp") { // Start listening to a specific measurement recording meterListener.EnableMeasurementEvents(instrument, null); } }; listener.SetMeasurementEventCallback((instrument, measurement, tags, state) => { Console.WriteLine($"Instrument {instrument.Name} has recorded the measurement: {measurement}"); }); listener.Start(); }

检查元素是否可为空的反射API

它提供来自反射成员的可空性信息和上下文：

ParameterInfo 参数 FieldInfo 字段 PropertyInfo 属性 EventInfo 事件

var example = new Example(); var nullabilityInfoContext = new NullabilityInfoContext(); foreach (var propertyInfo in example.GetType().GetProperties()) { var nullabilityInfo = nullabilityInfoContext.Create(propertyInfo); Console.WriteLine($"{propertyInfo.Name} property is {nullabilityInfo.WriteState}"); } // Output: // Name property is Nullable // Value property is NotNull class Example { public string? Name { get; set; } public string Value { get; set; } }

检查嵌套元素是否可为空的反射API

它允许您获取嵌套元素的可为空的信息, 您可以指定数组属性必须为非空，但元素可以为空，反之亦然。

Type exampleType = typeof(Example); PropertyInfo notNullableArrayPI = exampleType.GetProperty(nameof(Example.NotNullableArray)); PropertyInfo nullableArrayPI = exampleType.GetProperty(nameof(Example.NullableArray)); NullabilityInfoContext nullabilityInfoContext = new(); NullabilityInfo notNullableArrayNI = nullabilityInfoContext.Create(notNullableArrayPI); Console.WriteLine(notNullableArrayNI.ReadState); // NotNull Console.WriteLine(notNullableArrayNI.ElementType.ReadState); // Nullable NullabilityInfo nullableArrayNI = nullabilityInfoContext.Create(nullableArrayPI); Console.WriteLine(nullableArrayNI.ReadState); // Nullable Console.WriteLine(nullableArrayNI.ElementType.ReadState); // Nullable class Example { public string?[] NotNullableArray { get; set; } public string?[]? NullableArray { get; set; } }

ProcessId & ProcessPath

直接通过 Environment 获取进程ID和路径。

int processId = Environment.ProcessId string path = Environment.ProcessPath; Console.WriteLine(processId); Console.WriteLine(path);

Configuration 新增 GetRequiredSection()

和 DI 的 GetRequiredService() 是一样的, 如果缺失, 则会抛出异常。

WebApplicationBuilder builder = WebApplication.CreateBuilder(args); WebApplication app = builder.Build(); MySettings mySettings = new(); // Throws InvalidOperationException if a required section of configuration is missing app.Configuration.GetRequiredSection("MySettings").Bind(mySettings); app.Run(); class MySettings { public string? SettingValue { get; set; } }

CSPNG 密码安全伪随机数生成器

您可以从密码安全伪随机数生成器 (CSPNG) 轻松生成随机值序列。

它对于以下场景中很有用：

密钥生成

随机数

某些签名方案中的盐

// Fills an array of 300 bytes with a cryptographically strong random sequence of values. // GetBytes(byte[] data); // GetBytes(byte[] data, int offset, int count) // GetBytes(int count) // GetBytes(Span data) byte[] bytes = RandomNumberGenerator.GetBytes(300);

Native Memory API

.NET 6 引入了一个新的 API 来分配本机内存, NativeMemory 有分配和释放内存的方法。

unsafe { byte* buffer = (byte*)NativeMemory.Alloc(100); NativeMemory.Free(buffer); /* This class contains methods that are mainly used to manage native memory. public static class NativeMemory { public unsafe static void* AlignedAlloc(nuint byteCount, nuint alignment); public unsafe static void AlignedFree(void* ptr); public unsafe static void* AlignedRealloc(void* ptr, nuint byteCount, nuint alignment); public unsafe static void* Alloc(nuint byteCount); public unsafe static void* Alloc(nuint elementCount, nuint elementSize); public unsafe static void* AllocZeroed(nuint byteCount); public unsafe static void* AllocZeroed(nuint elementCount, nuint elementSize); public unsafe static void Free(void* ptr); public unsafe static void* Realloc(void* ptr, nuint byteCount); }*/ }

Power of 2

.NET 6 引入了用于处理 2 的幂的新方法。

'IsPow2' 判断指定值是否为 2 的幂。 'RoundUpToPowerOf2' 将指定值四舍五入到 2 的幂。

// IsPow2 evaluates whether the specified Int32 value is a power of two. Console.WriteLine(BitOperations.IsPow2(128)); // True // RoundUpToPowerOf2 rounds the specified T:System.UInt32 value up to a power of two. Console.WriteLine(BitOperations.RoundUpToPowerOf2(200)); // 256

WaitAsync on Task

您可以更轻松地等待异步任务执行, 如果超时会抛出 “TimeoutException”

Task operationTask = DoSomethingLongAsync(); await operationTask.WaitAsync(TimeSpan.FromSeconds(5)); async Task DoSomethingLongAsync() { Console.WriteLine("DoSomethingLongAsync started."); await Task.Delay(TimeSpan.FromSeconds(10)); Console.WriteLine("DoSomethingLongAsync ended."); } // Output: // DoSomethingLongAsync started. // Unhandled exception.System.TimeoutException: The operation has timed out.

新的数学API

新方法:

SinCos ReciprocalEstimate ReciprocalSqrtEstimate

新的重载：

Min, Max, Abs, Sign, Clamp 支持 nint 和 nuint DivRem 返回一个元组, 包括商和余数。

// New methods SinCos, ReciprocalEstimate and ReciprocalSqrtEstimate // Simultaneously computes Sin and Cos (double sin, double cos) = Math.SinCos(1.57); Console.WriteLine($"Sin = {sin}\nCos = {cos}"); // Computes an approximate of 1 / x double recEst = Math.ReciprocalEstimate(5); Console.WriteLine($"Reciprocal estimate = {recEst}"); // Computes an approximate of 1 / Sqrt(x) double recSqrtEst = Math.ReciprocalSqrtEstimate(5); Console.WriteLine($"Reciprocal sqrt estimate = {recSqrtEst}"); // New overloads // Min, Max, Abs, Clamp and Sign supports nint and nuint (nint a, nint b) = (5, 10); nint min = Math.Min(a, b); nint max = Math.Max(a, b); nint abs = Math.Abs(a); nint clamp = Math.Clamp(abs, min, max); nint sign = Math.Sign(a); Console.WriteLine($"Min = {min}\nMax = {max}\nAbs = {abs}"); Console.WriteLine($"Clamp = {clamp}\nSign = {sign}"); // DivRem variants return a tuple (int quotient, int remainder) = Math.DivRem(2, 7); Console.WriteLine($"Quotient = {quotient}\nRemainder = {remainder}"); // Output: // Sin = 0.9999996829318346 // Cos = 0.0007963267107331026 // Reciprocal estimate = 0.2 // Reciprocal sqrt estimate = 0.4472135954999579 // Min = 5 // Max = 10 // Abs = 5 // Clamp = 5 // Sign = 1 // Quotient = 0 // Remainder = 2

CollectionsMarshal.GetValueRefOrNullRef

这个是在字典中循环或者修改结可变结构体时用, 可以减少结构的副本复制, 也可以避免字典重复进行哈希计算，这个有点晦涩难懂，有兴趣的可以看看这个

https://github.com/dotnet/runtime/issues/27062

Dictionary dictionary = new() { { 1, new MyStruct { Count = 100 } } }; int key = 1; ref MyStruct value = ref CollectionsMarshal.GetValueRefOrNullRef(dictionary, key); // Returns Unsafe.NullRef() if it doesn't exist; check using Unsafe.IsNullRef(ref value) if (!Unsafe.IsNullRef(ref value)) { Console.WriteLine(value.Count); // Output: 100 // Mutate in-place value.Count++; Console.WriteLine(value.Count); // Output: 101 } struct MyStruct { public int Count { get; set; } }

ConfigureHostOptions

IHostBuilder 上的新 ConfigureHostOptions API, 可以更简单的配置应用。

public class Program { public static void Main(string[] args) { CreateHostBuilder(args).Build().Run(); } public static IHostBuilder CreateHostBuilder(string[] args) => Host.CreateDefaultBuilder(args) .ConfigureHostOptions(o => { o.ShutdownTimeout = TimeSpan.FromMinutes(10); }); }

Async Scope

.NET 6 引入了一种新的CreateAsyncScope方法, 当您处理 IAsyncDisposable 的服务时现有的CreateScope方法会引发异常, 使用 CreateAsyncScope 可以完美解决。

await using var provider = new ServiceCollection() .AddScoped() .BuildServiceProvider(); await using (var scope = provider.CreateAsyncScope()) { var example = scope.ServiceProvider.GetRequiredService(); } class Example : IAsyncDisposable { public ValueTask DisposeAsync() => default; }

加密类简化

DecryptCbc DecryptCfb DecryptEcb EncryptCbc EncryptCfb EncryptEcb

static byte[] Decrypt(byte[] key, byte[] iv, byte[] ciphertext) { using (Aes aes = Aes.Create()) { aes.Key = key; return aes.DecryptCbc(ciphertext, iv, PaddingMode.PKCS7); } }

到此这篇关于.NET 6新增的20个API介绍的文章就介绍到这了。希望对大家的学习有所帮助，也希望大家多多支持。

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。