.NET 6新增的20个API介绍_基础应用_

 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(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 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 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

 // 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 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(); }

 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; } }

 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; } }

 int processId = Environment.ProcessId string 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 missing app.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, R
                
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