一、创建实体类库

创建单独实体类

创建DI.Entity类库,用来存放所有的实体类,新建用户实体类,其结构如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DI.Entity
{
    public class UserEntity
    {
        public int UserId { get; set; }

        public string UserName { get; set; }

        public int Sex { get; set; }

        public int Age { get; set; }
    }
}

二、创建仓储接口类库

新建DI.Interface类库文件,存放所有接口,IUserRepository接口定义如下:

using DI.Entity;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DI.Interface
{
    public interface IUserRepository
    {
        List<UserEntity> GetUsers();
    }
}

三、创建仓储接口的实现类库

1、SQL Server数据库实现

新建DI.SqlServer类库文件,SqlServerUserRepository实现IUserRepository接口,SqlServerUserRepository类定义如下:

using DI.Entity;
using DI.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


namespace DI.SqlServer
{
    public class SqlServerUserRepository : IUserRepository
    {
        public List<UserEntity> GetUsers()
        {
            List<UserEntity> list = new List<UserEntity>()
            {
              new UserEntity(){UserId=1,UserName="王五",Sex=2,Age=21},
              new UserEntity(){UserId=2,UserName="赵六",Sex=2,Age=23},
            };

            return list;
        }
    }
}

2、Oracle数据库实现

新建DI.Oracle类库文件,OracleUserRepository实现IUserRepository接口,OracleUserRepository类定义如下:

using DI.Entity;
using DI.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DI.Oracle
{
    public class OracleUserRepository : IUserRepository
    {
        public List<UserEntity> GetUsers()
        {
            List<UserEntity> list = new List<UserEntity>()
            {
              new UserEntity(){UserId=1,UserName="张三",Sex=1,Age=24},
              new UserEntity(){UserId=2,UserName="李四",Sex=1,Age=22},
            };

            return list;
        }
    }
}

四、新建WebAPI项目

1、安装依赖项

通过NuGet安装所需的依赖项:Autofac、Autofac.WebApi2(如果使用的是WebApi1,这里需要安装WebApi)。

2、创建AutofacWebApiConfig类

AutofacWebApiConfig类定义如下:

using Autofac;
using Autofac.Integration.WebApi;
using DI.Interface;
using DI.SqlServer;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web;
using System.Web.Http;

namespace WebApi.AutofacDI
{
    public class AutofacWebApiConfig
    {
        public static void RegisterDependencies()
        {
            SetAutofacWebapi();
        }

        private static void SetAutofacWebapi()
        {
            ContainerBuilder builder = new ContainerBuilder();
            HttpConfiguration config = GlobalConfiguration.Configuration;
            // Register API controllers using assembly scanning.
            builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
            builder.RegisterAssemblyTypes(AppDomain.CurrentDomain.GetAssemblies()).Where(t => t.Name.EndsWith("Repository")).AsImplementedInterfaces();
            // 使用SQLserver数据库实现
            builder.RegisterType<SqlServerUserRepository>().As<IUserRepository>().InstancePerRequest();
            var container = builder.Build();
            // Set the WebApi dependency resolver.
            config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
        }
    }
}

3、修改Global.asax文件

修改后的Global.asax文件定义如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Http;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;
using WebApi.AutofacDI;

namespace WebApi
{
    public class WebApiApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            GlobalConfiguration.Configure(WebApiConfig.Register);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            // 配置依赖注入
            AutofacWebApiConfig.RegisterDependencies();
        }
    }
}

4、创建Users控制器

创建UsersController类,并在构造函数中注入,UsersController类定义如下:

using DI.Entity;
using DI.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace WebApi.Controllers
{
    public class UsersController : ApiController
    {
        private IUserRepository _userRepository;

        /// <summary>
        /// 构造函数中注入
        /// </summary>
        /// <param name="userRepository"></param>
        public UsersController(IUserRepository userRepository)
        {
            this._userRepository = userRepository;
        }

        public IHttpActionResult Get()
        {
            return Json <List<UserEntity>>( _userRepository.GetUsers());
        }
    }
}

5、测试

启动程序,然后在浏览器里面输入:http://localhost:51157/api/users,结果如下:

从结果中可以看出:这里使用的是SQLserver实现的。

修改AutofacWebApiConfig文件,用oracle实现,修改后的代码如下:

using Autofac;
using Autofac.Integration.WebApi;
using DI.Interface;
using DI.Oracle;
using DI.SqlServer;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web;
using System.Web.Http;

namespace WebApi.AutofacDI
{
    public class AutofacWebApiConfig
    {
        public static void RegisterDependencies()
        {
            SetAutofacWebapi();
        }

        private static void SetAutofacWebapi()
        {
            ContainerBuilder builder = new ContainerBuilder();
            HttpConfiguration config = GlobalConfiguration.Configuration;
            // Register API controllers using assembly scanning.
            builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
            builder.RegisterAssemblyTypes(AppDomain.CurrentDomain.GetAssemblies()).Where(t => t.Name.EndsWith("Repository")).AsImplementedInterfaces();
            // 使用SQLserver数据库实现
            //builder.RegisterType<SqlServerUserRepository>().As<IUserRepository>().InstancePerRequest();
            // 使用oracle数据库实现
            builder.RegisterType<OracleUserRepository>().As<IUserRepository>().InstancePerRequest();
            var container = builder.Build();
            // Set the WebApi dependency resolver.
            config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
        }
    }
}

运行结果:

从结果中可以看出:这里使用的是oracle实现的。

五、将Autofac的实现放到单独的类库中

新建DI.Server类库,将Autofac的注册单独放在类库中,AutofacWebApiConfig类定义如下:

using Autofac;
using Autofac.Integration.WebApi;
using DI.Interface;
using DI.SqlServer;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Mvc;

namespace DI.Server
{
    public class AutofacWebApiConfig
    {
        public static void RegisterDependencies()
        {
            SetAutofacWebapi();
        }

        private static void SetAutofacWebapi()
        {
            ContainerBuilder builder = new ContainerBuilder();
            HttpConfiguration config = GlobalConfiguration.Configuration;
            // Register API controllers using assembly scanning.
            builder.RegisterApiControllers(Assembly.LoadFrom(@"F:\Practice\WebAPI\WebApi依赖注入\DI\WebApiDIDemo\WebApi\bin\WebApi.dll"));
            builder.RegisterAssemblyTypes(AppDomain.CurrentDomain.GetAssemblies()).Where(t => t.Name.EndsWith("Repository")).AsImplementedInterfaces();
            builder.RegisterType<SqlServerUserRepository>().As<IUserRepository>().InstancePerRequest();
            var container = builder.Build();
            // Set the WebApi dependency resolver.
            config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
        }
    }
}

注意:

如果是在单独的类库项目中,注册Api控制器的时候要加载WebApi项目所有的程序集文件,不要使用builder.RegisterApiControllers(Assembly.GetExecutingAssembly()),这里找到的当前程序集是类库文件,不是WebApi项目的程序集文件,在控制器里面不会实现注入。

2、修改Global.asax文件

修改后的Global.asax文件定义如下:

using DI.Server;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Http;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;


namespace WebApi
{
    public class WebApiApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            GlobalConfiguration.Configure(WebApiConfig.Register);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            // 配置依赖注入(注意:这里使用的是单独类库里面的AutofacWebApiConfig类)
            AutofacWebApiConfig.RegisterDependencies();
        }
    }
}

运行程序,效果和上面的一样。

到此这篇关于Web API中使用Autofac实现依赖注入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阿兔在线工具。

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