8 .NET 配置

word文档地址：https://github.com/IceEmblem/LearningDocuments/tree/master/%E5%AD%A6%E4%B9%A0%E8%B5%84%E6%96%99/Windows%20%E5%B9%B3%E5%8F%B0/Net

本文主要介绍IConfiguration、ConfigurationBuilder、IConfigurationSource的之间的关系和用法，如果你已经了解其用途，可以跳过
IConfiguration：配置，其包含整个程序的配置数据
IConfigurationSource：配置源，其有多种实现，包括Json、ini、xml等
ConfigurationBuilder：配置生成器，其利用IConfigurationSource生成IConfiguration

// IConfiguration使用 : 来分隔层次结构，如下配置结构为
// {
//     format:{
//         dateTime:{
//             longDatePattern: "dddd, MMMM d, yyyy",
//             longTimePattern: "h:mm:ss tt"
//             ...
//         }
//     }
// }
Dictionary source = new Dictionary
{
    ["format:dateTime:longDatePattern"] = "dddd, MMMM d, yyyy",
    ["format:dateTime:longTimePattern"] = "h:mm:ss tt",
    ["format:dateTime:shortDatePattern"] = "M/d/yyyy",
    ["format:dateTime:shortTimePattern"] = "h:mm tt",
};

// 配置
IConfiguration config =
    // 新建ConfigurationBuilder
    new ConfigurationBuilder()
    // 添加内存配置源
    .Add(new MemoryConfigurationSource { InitialData = source })
    // 添加Json配置源
    .AddJsonFile("./appsettings.json")
    // 生成Configuration
.Build();

// 使用 GetSection 获取数据
var longDatePattern = config.GetSection("format").GetSection("dateTime").GetValue("longDatePattern");
Console.WriteLine(longDatePattern);

// 当然，你也可以直接获取数据， : 代表层次结构
var longDatePattern2 = config["format:dateTime:longDatePattern"];
Console.WriteLine(longDatePattern2);

.net core 提供的配置源有下面几种

1.内存配置源
内存配置源的实现为MemoryConfigurationSource，其提供了2个扩展方法将源快速添加到ConfigurationBuilder中

public static IConfigurationBuilder AddInMemoryCollection(
this IConfigurationBuilder configurationBuilder);
public static IConfigurationBuilder AddInMemoryCollection(
this IConfigurationBuilder configurationBuilder,  
IEnumerable> initialData);

2.环境变量配置源
环境变量配置源的实现为EnvironmentVariablesConfigurationSource
包：Microsoft.Extensions.Configuration.EnvironmentVariables

public static IConfigurationBuilder AddEnvironmentVariables(
    this IConfigurationBuilder configurationBuilder);
public static IConfigurationBuilder AddEnvironmentVariables(
    this IConfigurationBuilder configurationBuilder, 
    string prefix);

3.命令行参数
命令行参数配置源的实现为CommandLineConfigurationSource
包：Microsoft.Extensions.Configuration.CommandLine

public static IConfigurationBuilder AddCommandLine(
    this IConfigurationBuilder configurationBuilder, 
    string[] args);
public static IConfigurationBuilder AddCommandLine(
    this IConfigurationBuilder configurationBuilder, 
    string[] args, 
    IDictionary switchMappings);

4.Json文件
其实现的配置源为JsonConfigurationSource
包：Microsoft.Extensions.Configuration.Json
包提供的添加Json配置源的扩展

public static class JsonConfigurationExtensions
{
    public static IConfigurationBuilder AddJsonFile(
        this IConfigurationBuilder builder, 
        Action configureSource);

    public static IConfigurationBuilder AddJsonFile(
        this IConfigurationBuilder builder, 
        string path);

    public static IConfigurationBuilder AddJsonFile(
        this IConfigurationBuilder builder, 
        string path, 
        bool optional);

    public static IConfigurationBuilder AddJsonFile(
        this IConfigurationBuilder builder, 
        string path,            // 配置源路径
        bool optional,          // 是否可选配置源
        bool reloadOnChange);   // 改变是否重新载入
}

5.Xml文件
其实现为XmlConfiguationSource
包：Microsoft.Extensions.Configuration.Xml
包提供的XML配置源的扩展

public static class XmlConfigurationExtensions
{
    public static IConfigurationBuilder AddXmlFile(
        this IConfigurationBuilder builder, 
        string path, 
        bool optional, 
        bool reloadOnChange);

    ...
}

XML文件示例

6.ini文件
其实现为IniConfigurationSource
包：Microsoft.Extensions.Configuration.Ini
包提供的扩展

public static class IniConfigurationExtensions
{
    public static IConfigurationBuilder AddIniFile(
        this IConfigurationBuilder builder, 
        string path, 
        bool optional, 
        bool reloadOnChange);

    ...
}

INI文件示例

Gender = "Male"
Age = "18"
ContactInfo:EmailAddress = "foobar@outlook.com"
ContactInfo:PhoneNo = "123456789"

1.添加配置源
我们可以在IHostBuilder.ConfigureHostConfiguration中添加配置源

Host.CreateDefaultBuilder(args)
    .ConfigureHostConfiguration((config) => {
        Dictionary source = new Dictionary
        {
            ["format:dateTime:longDatePattern"] = "dddd, MMMM d, yyyy",
            ["format:dateTime:longTimePattern"] = "h:mm:ss tt",
            ["format:dateTime:shortDatePattern"] = "M/d/yyyy",
            ["format:dateTime:shortTimePattern"] = "h:mm tt",
        };
        config.AddInMemoryCollection(source);
    })

2.使用配置
我们可以在任何地方使用依赖注入获取IConfiguration

public Startup(IConfiguration configuration)
{
    var longDatePattern2 = configuration["format:dateTime:longDatePattern"];
}