.net core 學習 讀取配置文件

在空項目中是沒有配置文件的，首先要新建一個，配置文件內容如下，下面來讀取各個內容

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=(localdb)\\MSSQLLocalDB;Database=_CHANGE_ME;Trusted_Connection=True;MultipleActiveResultSets=true",
  },
  "Name": "張三",
  "Person": {
    "Name": "張三",
    "Age": 18
  },
  "Persons": [
    {
      "Name": "張三",
      "Age": 18
    },
    {
      "Name": "李四",
      "Age": 18
    }
  ]
}

有時會出現中文讀取亂碼，用計事本打開，然后另存為 utf-8 就可以了

ConfigurationBuilder configurationBuilder =new ConfigurationBuilder();
//配置文件路徑
configurationBuilder.SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("appsettings.json");
var configuration = configurationBuilder.Build();
            
//讀取連接字符串
var value1= configuration.GetConnectionString("DefaultConnection");

//讀取自定義內容
var value2 = configuration.GetValue<string>("Name");
var value3 = configuration.GetValue<string>("Person:Name");
var value4 = configuration.GetValue<int>("Person:Age");
var value5 = configuration.GetValue<string>("Persons:0:Name");
var value6 = configuration.GetValue<int>("Persons:0:Age");

索引不是中括號感覺有點不適應

上面是讀取基礎值，其實還可以將 Person 和 Persons 讀取為對象，不過寫法要改下，首先再 Startup 類中添加一個構造函數和字段

public Startup(IConfiguration _configuration)
{
   Configuration = _configuration;
}

public IConfiguration Configuration;

然后在 ConfigureServices 方法添加如下

services.Configure<Person>(Configuration.GetSection("Person"));
services.Configure<List<Person>>(Configuration.GetSection("Persons"));

之后是控制器中

private Person person;
private List<Person> persons;
public ConfigurationController(IOptions<Person> _person, IOptions<List<Person>> _persons)
{
    person = _person.Value;
    persons = _persons.Value;
}

以上就是 asp.net core 讀取配置文件的方法