public static IWebHostBuilder UseStartup(this IWebHostBuilder builder, Type startupType)
{
var typeInfo = startupType.GetTypeInfo();
var constructors = typeInfo.GetConstructors()
.Where(x => x.IsPublic)
.OrderBy(x => x.GetParameters().Length);
IStartup startup = null;
foreach (var constructor in constructors)
{
var parameters = constructor.GetParameters();
var objParams = new object[parameters.Length];
int i = 0;
for (i = 0; i < parameters.Length; i++)
{
if (DefaultParamterValue.TryGetDefaultValue(parameters[i], out var value))
{
objParams[i] = value;
var x = new ConfigurationBuilder();
}
else
{
break;
}
}
if (i < parameters.Length)
{
continue;
}
startup = (IStartup)constructor.Invoke(objParams);
break;
}
if (startup == null)
{
throw new InvalidOperationException("操作失败，无法构造出Startup类");
}
return(builder.Configure(
services => startup.ConfigureServices(services),
app => startup.Configure(app)));
}
public bool TryBindModel(HttpContext httpContext, IValueProvider valueProvider, ParameterInfo parameter, out object value)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
if (valueProvider == null)
{
throw new ArgumentNullException(nameof(valueProvider));
}
if (parameter == null)
{
throw new ArgumentNullException(nameof(parameter));
}
value = null;
if (!String.IsNullOrWhiteSpace(httpContext.RouteEntity.ParameterValue) &&
String.Equals(httpContext.RouteEntity.DefaultParameter,
parameter.Name,
StringComparison.OrdinalIgnoreCase))
{
if (httpContext.RouteEntity.ParameterValue != null)
{
TypeConverter converter = TypeDescriptor.GetConverter(parameter.ParameterType);
try
{
value = converter.ConvertTo(httpContext.RouteEntity.ParameterValue, parameter.ParameterType);
return(true);
}
catch
{
}
}
}
var binderProviders = httpContext.Service.GetRequiredService <IModelBinderProvider>();
var modelBinder = binderProviders.GetBinder(parameter.ParameterType);
var modelMetadata = httpContext.Service.GetRequiredService <IModelMetadataProvider>().GetMetadataForType(null, parameter.ParameterType);
//var modelBinderModelBinders.Binders.GetBinder(paramDescriptor.ParameterType);
if (TryBindValue(modelBinder, modelMetadata, httpContext, valueProvider, "", out var paramValue))
{
value = paramValue;
return(true);
}
if (TryBindValue(modelBinder, modelMetadata, httpContext, valueProvider, parameter.Name, out paramValue))
{
value = paramValue;
return(true);
}
// 尝试依赖注入
modelBinder = binderProviders.GetBinder(typeof(IServiceProvider));
if (TryBindValue(modelBinder, modelMetadata, httpContext, valueProvider, "", out paramValue))
{
value = paramValue;
return(true);
}
if (DefaultParamterValue.TryGetDefaultValue(parameter, out paramValue))
{
// 注：默认值可能为Null
value = paramValue;
return(true);
}
else if (TypeHelper.IsNullableValueType(modelMetadata.ModelType))
{
value = null;
return(true);
}
else
{
return(false);
}
}
