ASP.NET Core 1.0 Configuration 配置管理

项目结构

配置的接口定义与基础实现 Microsoft.Extensions.Configuration  配置文件的基础实现
Microsoft.Extensions.Configuration.Abstractions  配置文件的基础实现的接口定义
Microsoft.Extensions.Configuration.Binder  特殊配置文件实现

配置的扩展 Microsoft.Extensions.Configuration.CommandLine  命令行扩展
Microsoft.Extensions.Configuration.EnvironmentVariables  环境变量扩展
Microsoft.Extensions.Configuration.FileExtensions  文本类型扩展
Microsoft.Extensions.Configuration.FileProviderExtensions 用来检测配置文本是否变动
Microsoft.Extensions.Configuration.Ini  Ini文件类型扩展
Microsoft.Extensions.Configuration.Json Json文件类型扩展
Microsoft.Extensions.Configuration.Xml   Xml文件类型扩展

ASP.NET Core 1.0 中抛弃了原先的web.config文件机制，引用了现有的appsettings.json文件机制，配置的文件的类型可以是JSON,XML,INI等，如在Startup类中:

/// <summary>
/// 配置信息
/// </summary>
public IConfigurationRoot Configuration { get; set; }

/// <summary>
/// 程序入口点
/// </summary>
/// <param name="env"></param>
public Startup(IHostingEnvironment env)
{
var builder = new ConfigurationBuilder()
.AddJsonFile("appsettings.json")
.AddEnvironmentVariables();
Configuration = builder.Build();
}

新的配置机制基于Microsoft.Extensions.Configuration命名空间，IConfiguration接口中定义配置信息的实例接口

/// <summary>
/// Represents a set of key/value application configuration properties.
/// </summary>
public interface IConfiguration
{
/// <summary>
/// Gets or sets a configuration value.
/// </summary>
/// <param name="key">The configuration key.</param>
/// <returns>The configuration value.</returns>
string this[string key] { get; set; }

/// <summary>
/// Gets a configuration sub-section with the specified key.
/// </summary>
/// <param name="key">The key of the configuration section.</param>
/// <returns>The <see cref="IConfigurationSection"/>.</returns>
/// <remarks>
///     This method will never return <c>null</c>. If no matching sub-section is found with the specified key,
///     an empty <see cref="IConfigurationSection"/> will be returned.
/// </remarks>
IConfigurationSection GetSection(string key);

/// <summary>
/// Gets the immediate descendant configuration sub-sections.
/// </summary>
/// <returns>The configuration sub-sections.</returns>
IEnumerable<IConfigurationSection> GetChildren();

IChangeToken GetReloadToken();
}

IConfigurationRoot接口继承IConfiguration接口，定义了Reload方法; IConfigurationProvider 是定义所有实现的基础接口约定；IConfigurationBuilder接口是基础实现的构造器，ConfigurationBuilder类定义了基础具体实现。

扩展方法

支持多文件类型配置，是在IConfigurationBuilder构造器接口上进行扩展方法

var configurationBuilder = new ConfigurationBuilder();
configurationBuilder.AddIniFile(_iniConfigFilePath);
configurationBuilder.AddJsonFile(_jsonConfigFilePath);
configurationBuilder.AddXmlFile(_xmlConfigFilePath);
configurationBuilder.AddInMemoryCollection(_memConfigContent);
var config = configurationBuilder.Build();

如AddJsonFile扩展方法

/// <summary>
/// Adds the JSON configuration provider at <paramref name="path"/> to <paramref name="configurationBuilder"/>.
/// </summary>
/// <param name="configurationBuilder">The <see cref="IConfigurationBuilder"/> to add to.</param>
/// <param name="path">Absolute path or path relative to <see cref="IConfigurationBuilder.BasePath"/> of
/// <paramref name="configurationBuilder"/>.</param>
/// <param name="optional">Determines if loading the configuration provider is optional.</param>
/// <returns>The <see cref="IConfigurationBuilder"/>.</returns>
/// <exception cref="ArgumentException">If <paramref name="path"/> is null or empty.</exception>
/// <exception cref="FileNotFoundException">If <paramref name="optional"/> is <c>false</c> and the file cannot
/// be resolved.</exception>
public static IConfigurationBuilder AddJsonFile(
this IConfigurationBuilder configurationBuilder,
string path,
bool optional)
{
if (configurationBuilder == null)
{
throw new ArgumentNullException(nameof(configurationBuilder));
}

if (string.IsNullOrEmpty(path))
{
throw new ArgumentException(Resources.Error_InvalidFilePath, nameof(path));
}

var fullPath = Path.Combine(configurationBuilder.GetBasePath(), path);

if (!optional && !File.Exists(fullPath))
{
throw new FileNotFoundException(Resources.FormatError_FileNotFound(fullPath), fullPath);
}

configurationBuilder.Add(new JsonConfigurationProvider(fullPath, optional: optional));

return configurationBuilder;
}