ASP.NET Core - 读取配置文件

appsettings.json文件

---

在appsettings.json中配置参数：

{
  "ConnectionStrings": {
    "Default": "Server=.; Database=demoDb; Trusted_Connection=True;"
  },
  "AllowedHosts": "*"
}

获取数据库连接字符串

---

GetConnectionString

public Startup(IConfiguration configuration)
{
    var defaultConnectionString = configuration.GetConnectionString("Default");
}

获取参数

---

GetSection

返回键值对对象。

public Startup(IConfiguration configuration)
{
    var allowedHosts = configuration.GetSection("AllowedHosts").Value;
}

GetValue

返回泛型类型。

public Startup(IConfiguration configuration)
{
    var allowedHosts = configuration.GetValue<string>("AllowedHosts");
}

KeyValue

返回string类型。

public Startup(IConfiguration configuration)
{
    var allowedHosts = configuration["AllowedHosts"];
}

手动初始化IConfiguration

---

可以用于单元测试项目，手动初始化IConfiguration。

需要添加程序集：
Install-Package Microsoft.Extensions.Configuration.Abstractions
Install-Package Microsoft.Extensions.Configuration.Json

需要添加引用：
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Configuration.Json;

var configuration = new ConfigurationBuilder()
    .Add(new JsonConfigurationSource { Path = "appsettings.json" })
    .Build()
    
// 指定基路径
var configuration = new ConfigurationBuilder()
    .SetBasePath(System.Environment.CurrentDirectory.Split("bin")[0])
    .Add(new JsonConfigurationSource { Path = "appsettings.json" })
    .Build();