net Core做一个webApi的简单实例

用NetCore 和Dapper 和mySql做一个简单的实例，

一准备工作

1：VS2017+windos系统，也可以用其他的操作系统和工具

2：一台Cenetos的虚拟机或者虚拟机

二：开始

1：用微软官方的netCore的ToDo项目改造，项目的主体结构如下图，源连接

https://docs.microsoft.com/zh-cn/aspnet/core/tutorials/first-web-api

1：打开Nuget控制台，安装 MySQL官方.NET Core驱动,并且支持 EF Core

 >Install-Package SapientGuardian.MySql.Data -Pre

2：打开Nuget控制台，安装Dapper

>Install-Package Dapper -Pre

3：在Models文件夹下新建ToDoItem 的实体

 public class ToDoItem
    {
        [Required]
        public string ID { get; set; }

        [Required]
        public string Name { get; set; }

        [Required]
        public string Notes { get; set; }

        public bool Done { get; set; }
    }

4：在appsettings.json里面配置MySql的数据库连接字符串，然后点开appsettings.json的属性将“复制到输出目录”项的值改为“始终复制”，

SslMode=none的作用是解决连接的时候报SSL错误的

  "ConnectionStrings": {
    "SqlServerConnection": "Server=(LocalDb)\MSSQLLocalDB, Database=test",
    "MySqlConnection": "Server=自己的服务器;Database=test;User ID=root;Password=111111;SslMode=none"
  }

 5：在Common下面新建一个AppConfigurtaionServices的类，用于读取appsettings.json里面的连接字符串(appsettings.json属性如果没有选中始终复制，在代码运行的时候，

IConfiguration 会报错

)

public class AppConfigurtaionServices
    {
        public static IConfiguration Configuration { get; set; }
        static AppConfigurtaionServices()
        {
            Configuration = new ConfigurationBuilder()
            .Add(new JsonConfigurationSource { Path = "appsettings.json", ReloadOnChange = true })
            .Build();
        }
    }

6：新建一个Interfaces文件夹，然后下面建一个IToDoRepository的接口类

 public interface IToDoRepository
    {
        bool DoesItemExist(string id);
        IEnumerable<ToDoItem> All();
        ToDoItem Find(string id);
        int Insert(ToDoItem item);
        int Update(ToDoItem item);
        int Delete(string id);
    }

　　

7：新建一个Services然后下面新建ToDoRepository类 是我们的数据仓储类 记得要引用(using Dapper;和 using MySql.Data.MySqlClient;)

 public class ToDoRepository : IToDoRepository
    {
        private  static  string DefaultSqlConnectionString = "";
        public ToDoRepository()
        {
            DefaultSqlConnectionString = AppConfigurtaionServices.Configuration.GetConnectionString("MySqlConnection"); 
    
        }
        public static IDbConnection GetSqlConnection(string sqlConnectionString = null)
        {
            if (string.IsNullOrWhiteSpace(sqlConnectionString))
            {
                sqlConnectionString = DefaultSqlConnectionString;
            }
            IDbConnection conn = new MySqlConnection(sqlConnectionString);
            conn.Open();
            return conn;
        }
        /// <summary>
        /// 获取全部
        /// </summary>
        /// <returns></returns>
        public IEnumerable<ToDoItem> All()
        {
            using (IDbConnection conn = GetSqlConnection())
            {
                string strsql = "select * from ToDoItem";
                return conn.Query<ToDoItem>(strsql, null);
            }
        }

        /// <summary>
        /// 查询是否存在
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public bool DoesItemExist(string id)
        {
            using (IDbConnection conn = GetSqlConnection())
            {
                int cout = conn.Query<int>("select count(*) from ToDoItem where  ID=@ID", new { ID = id }).FirstOrDefault();
                if (cout > 0)
                    return true;
                else
                    return false;
            }
        }
        /// <summary>
        /// 删除
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public int Delete(string id)
        {
            using (IDbConnection conn = GetSqlConnection())
            {
                string strsql = "DELETE from ToDoItem where ID=@ID";
                return conn.Execute(strsql, new { ID = id });
            }

        }

        /// <summary>
        /// 查询整个对象
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public ToDoItem Find(string id)
        {
            using (IDbConnection conn = GetSqlConnection())
            {
                string strsql = "select * from  ToDoItem where ID=@ID";
                return conn.Query<ToDoItem>(strsql, new { ID = id }).FirstOrDefault();
            }
        }
        /// <summary>
        /// 新增项
        /// </summary>
        /// <param name="item"></param>
        /// <returns></returns>
        public int Insert(ToDoItem item)
        {
            using (IDbConnection conn = GetSqlConnection())
            {
                string strsql = "INSERT into ToDoItem(ID,Name,Notes,Done)values(@ID,@Name,@Notes,@Done)";
                return conn.Execute(strsql, item);
            }
        }

        /// <summary>
        /// 修改
        /// </summary>
        /// <param name="item"></param>
        /// <returns></returns>
        public int Update(ToDoItem item)
        {
            using (IDbConnection conn = GetSqlConnection())
            {
                string strsql = " UPDATE ToDoItem SET Name=@Name,Notes=@Notes,Done=@Done where ID=@ID";
                return conn.Execute(strsql, item);
            }
        }

     

    }

 8：在Controller下面新增一个ToDoItemsController的控制器，记得添加相关的命名空间

 [Route("api/[controller]")]
    public class ToDoItemsController : Controller
    {
        private readonly IToDoRepository _toDoRepository;

        public ToDoItemsController(IToDoRepository toDoRepository)
        {
            _toDoRepository = toDoRepository;
        }

        /// <summary>
        /// 获取数据
        /// </summary>
        /// <returns></returns>
        [HttpGet]
        public IActionResult List()
        {
            return Ok(_toDoRepository.All());
        }
        /// <summary>
        /// 新增项
        /// </summary>
        /// <param name="item"></param>
        /// <returns></returns>
        [HttpPost]
        public IActionResult Create([FromBody] ToDoItem item)
        {
            try
            {
                if (item == null || !ModelState.IsValid)
                {
                    return BadRequest("没有通过验证");
                }
                bool itemExists = _toDoRepository.DoesItemExist(item.ID);
                if (itemExists)
                {
                    return StatusCode(StatusCodes.Status409Conflict, "已经存在此项");
                }
                _toDoRepository.Insert(item);
            }
            catch (Exception)
            {
                return BadRequest("创建失败");
            }

            return Ok(item);
        }

        /// <summary>
        /// 修改项
        /// </summary>
        /// <param name="item"></param>
        /// <returns></returns>
        [HttpPut]
        public IActionResult Edit([FromBody] ToDoItem item)
        {
            try
            {
                if(item==null || !ModelState.IsValid)
                    return BadRequest("没有通过必填验证");
                var existingItem = _toDoRepository.Find(item.ID);
                if(existingItem==null)
                {
                    return NotFound("没有发现此记录");
                }
                _toDoRepository.Update(item);
            }
            catch(Exception)
            {
                return BadRequest("修改失败");
            }
            return NoContent();
        }

        /// <summary>
        /// 删除
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        [HttpDelete("{id}")]
        public IActionResult Delete(string id)
        {
            try
            {
                var item = _toDoRepository.Find(id);
                if (item == null)
                    return NotFound("没有此记录");
                _toDoRepository.Delete(id);
            }
            catch(Exception )
            {
                return BadRequest("删除失败");
            }

            return NoContent();
        }

     

    }

　9：在ConfigureServices里配置IToDoRepository 和ToDoRepository服务

   services.AddSingleton<IToDoRepository, Services.ToDoRepository>();

 10：配置Swagger(丝袜哥)具体Swagger的基础知识可以连接到

https://docs.microsoft.com/zh-cn/aspnet/core/tutorials/web-api-help-pages-using-swagger?tabs=visual-studio

10.1：在Nuget控制台添加引用

   >Install-Package Swashbuckle.AspNetCore

10.2:在Startup类中配置Swagger

10.2.1：在ConfigureServices方法里面添加Swagger服务

    //添加Swagger服务
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new Info
                {
                    Version = "v1",
                    Title = "ToDo API",
                    Description = "A simple example ASP.NET Core Web API",
                    TermsOfService = "None",
                    Contact = new Contact { Name = "Shayne Boyer", Email = "", Url = "https://twitter.com/spboyer" },
                    License = new License { Name = "Use under LICX", Url = "https://example.com/license" }
                });

                var basePath = PlatformServices.Default.Application.ApplicationBasePath;
                var xmlPath = Path.Combine(basePath, "ToDoApi.xml");
                c.IncludeXmlComments(xmlPath);
            });

  10.2.2：在Configure配置Swagger服务

app.UseSwagger();
//配置Swagger服务
app.UseSwaggerUI(c =>
{
 c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
});

 10.3：最终的Startup类如下

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.PlatformAbstractions;
using Swashbuckle.AspNetCore.Swagger;
using System.IO;
using ToDoApi.Interfaces;

namespace ToDoApi
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        //添加服务
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
   
            //添加Swagger服务
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new Info
                {
                    Version = "v1",
                    Title = "ToDo API",
                    Description = "A simple example ASP.NET Core Web API",
                    TermsOfService = "None",
                    Contact = new Contact { Name = "Shayne Boyer", Email = "", Url = "https://twitter.com/spboyer" },
                    License = new License { Name = "Use under LICX", Url = "https://example.com/license" }
                });

                var basePath = PlatformServices.Default.Application.ApplicationBasePath;
                var xmlPath = Path.Combine(basePath, "ToDoApi.xml");
                c.IncludeXmlComments(xmlPath);
            });
            services.AddSingleton<IToDoRepository, Services.ToDoRepository>();
        }

        // 配置服务
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseSwagger();
            //配置Swagger服务
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
            });
            //配置开发环境
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseMvc();
        }
    }
}

10.4：启动项设置为swagger启动 

在launchSettings.json做如下修改

这样你的项目用IIS Express启动来就是swagger界面

11：最终效果

11.2：测试获取数据的方法

12:对NetCore的理解还很浅，只是做了一个简单的demo希望能帮到你，只是写了mysql的，如果是要用SqlServer,则修改读取SqlServerConnection的数据连接然后把数据仓储里面的 MySql.Data.MySqlClien改成Sql server的就可以了

 13：demo连接：

https://files.cnblogs.com/files/gouguo/ToDoApi.rar