20 个 .NET 6 新增的 API

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); 

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<GitHubUser>(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

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

PriorityQueue<string, int> 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

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

// 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// ...

var builder = WebApplication.CreateBuilder(args);var app = builder.Build();// Create Metervar meter = new Meter("MetricsApp", "v1.0");// Create counterCounter 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 Listenervoid 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();}

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 NotNullclass Example{    public string? Name { get; set; }    public string Value { get; set; }}

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);              // NotNullConsole.WriteLine(notNullableArrayNI.ElementType.ReadState);  // NullableNullabilityInfo nullableArrayNI = nullabilityInfoContext.Create(nullableArrayPI);Console.WriteLine(nullableArrayNI.ReadState);                // NullableConsole.WriteLine(nullableArrayNI.ElementType.ReadState);    // Nullableclass Example{    public string?[] NotNullableArray { get; set; }    public string?[]? NullableArray { get; set; }}

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

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

// 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);

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);    }*/}

// 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

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.

// New methods SinCos, ReciprocalEstimate and ReciprocalSqrtEstimate// Simultaneously computes Sin and Cos(double sin, double cos) = Math.SinCos(1.57);Console.WriteLine($"Sin = {sin}\nCos = {cos}");// Computes an approximate of 1 / xdouble recEst = Math.ReciprocalEstimate(5);Console.WriteLine($"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

Dictionary<int, MyStruct> 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; }}

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);            });}

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

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