在Ubuntu云主机上创建 .NET Hello World Web Server

在Ubuntu云主机上创建 .NET Hello World Web Server

在Ubuntu云主机上创建 .NET Hello World Web Server，编译并运行 .NET Hello World Web Server。

1、运行环境

1-1、服务器端运行环境

• 操作系统：Linux version 4.4.0-62-generic (buildd@lcy01-30) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) ) #83-Ubuntu SMP Wed Jan 18 14:10:15 UTC 2017
• .NET SDK 版本：dotnet-sdk-2.1

2、操作步骤

2-1、切换到目录/tmp

执行以下命令，切换到目录/tmp：

cd /tmp

2-2、创建Hello World Web Server

执行以下命令，创建Hello World Web Server：

dotnet new web -o myProject
cd myProject

执行以下命令，查看Program.cs：

more Program.cs 

Program.cs：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace myProject
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup();
    }
}

执行以下命令，查看Startup.cs：

more Startup.cs 

Startup.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;

namespace myProject
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add servic
es to the container.
        // For more information on how to configure your application, visit http
s://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
        }

        // This method gets called by the runtime. Use this method to configure 
the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.Run(async (context) =>
            {
                await context.Response.WriteAsync("Hello World!");
            });
        }
    }
}

2-3、运行Hello World Web Server

执行以下命令，运行Hello World Web Server：

dotnet run

Hello World Web Server 输出：

Using launch settings from /tmp/myProject/Properties/launchSettings.json...
Hosting environment: Development
Content root path: /tmp/myProject
Now listening on: https://localhost:5001
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.

2-4、访问Hello World Web Server

打开另一个终端，执行以下命令，访问Hello World Web Server：

wget http://localhost:5000/

输出：

--2018-07-31 23:20:09--  http://localhost:5000/
Resolving localhost (localhost)... ::1, 127.0.0.1
Connecting to localhost (localhost)|::1|:5000... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified
Saving to: ‘index.html’

index.html              [ <=>                ]      12  --.-KB/s    in 0s      

2018-07-31 23:20:09 (1.30 MB/s) - ‘index.html’ saved [12]

执行以下命令，查看index.html：

more index.html

index.html内容：

Hello World!

2-5、非常正常关闭Hello World Web Server的处理

运行的Hello World Web Server需要通过Ctrl + C 来关闭。如果其它方式，例如Ctrl + Z来中断程序运行时，再次运行Hello World Web Server，将出现以下错误：

Using launch settings from /tmp/myProject/Properties/launchSettings.json...
crit: Microsoft.AspNetCore.Server.Kestrel[0]
      Unable to start Kestrel.
System.IO.IOException: Failed to bind to address https://127.0.0.1:5001: address already in use. ---> Microsoft.AspNetCore.Connections.AddressInUseException: Address already in use ---> System.Net.Sockets.SocketException: Address already in use
   at System.Net.Sockets.Socket.UpdateStatusAfterSocketErrorAndThrowException(SocketError error, String callerName)
   at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress)
   at System.Net.Sockets.Socket.Bind(EndPoint localEP)
   at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransport.BindAsync()
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransport.BindAsync()
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.<>c__DisplayClass22_0`1.<g__OnBind|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindEndpointAsync(ListenOptions endpoint, AddressBindContext context)
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindEndpointAsync(ListenOptions endpoint, AddressBindContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.LocalhostListenOptions.BindAsync(AddressBindContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.AddressesStrategy.BindAsync(AddressBindContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindAsync(IServerAddressesFeature addresses, KestrelServerOptions serverOptions, ILogger logger, Func`2 createBinding)
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)

Unhandled Exception: System.IO.IOException: Failed to bind to address https://127.0.0.1:5001: address already in use. ---> Microsoft.AspNetCore.Connections.AddressInUseException: Address already in use ---> System.Net.Sockets.SocketException: Address already in use
   at System.Net.Sockets.Socket.UpdateStatusAfterSocketErrorAndThrowException(SocketError error, String callerName)
   at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress)
   at System.Net.Sockets.Socket.Bind(EndPoint localEP)
   at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransport.BindAsync()
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransport.BindAsync()
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.<>c__DisplayClass22_0`1.<g__OnBind|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindEndpointAsync(ListenOptions endpoint, AddressBindContext context)
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindEndpointAsync(ListenOptions endpoint, AddressBindContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.LocalhostListenOptions.BindAsync(AddressBindContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.AddressesStrategy.BindAsync(AddressBindContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindAsync(IServerAddressesFeature addresses, KestrelServerOptions serverOptions, ILogger logger, Func`2 createBinding)
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.StartAsync(CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Hosting.WebHostExtensions.RunAsync(IWebHost host, CancellationToken token, String shutdownMessage)
   at Microsoft.AspNetCore.Hosting.WebHostExtensions.RunAsync(IWebHost host, CancellationToken token)
   at Microsoft.AspNetCore.Hosting.WebHostExtensions.Run(IWebHost host)
   at myProject.Program.Main(String[] args) in /tmp/myProject/Program.cs:line 17

其原因是端口5000、5001没有释放。执行以下命令，查看5000端口使用情况：

lsof -i:5000

输出：

COMMAND   PID   USER   FD   TYPE    DEVICE SIZE/OFF NODE NAME
dotnet  14989 ubuntu  101u  IPv4 246793676      0t0  TCP localhost:5000 (LISTEN)
dotnet  14989 ubuntu  102u  IPv6 246793677      0t0  TCP localhost:5000 (LISTEN)

执行以下命令，释放端口占用：

kill -9 14989

再次执行以下命令，运行Hello World Web Server：

dotnet run

2-6、安装lsof

如果没有安装lsof，那么执行以下命令安装lsof：

sudo apt-get install lsof

参考资料：

• Programming C# on Ubuntu Linux