如何在Golang中的运行时中动态转换类型？

Here is my example: http://play.golang.org/p/D608cYqtO5

Basically I want to do this:

theType := reflect.TypeOf(anInterfaceValue)
theConvertedValue := anInterfaceValue.(theType)

The notation

value.(type)

is called a type-assertion. The type in an assertion has to be known at compile-time and it's always a type name.

In your playground example SetStruct2 could use a type-switch to handle different types for its second argument:

switch v := value.(type) {
case Config:
    // code that uses v as a Config
case int:
    // code that uses v as an int
}

You cannot, however, assert an interface to be something dynamic (like in your code). Because otherwise the compiler could not type-check your program.

Edit:

I don't want to case them one by one if there is another way to do so?

You can use reflection to work type-agnostically. You can then set stuff randomly on values but it will panic if you perform an illegal operation for a type.

If you want to benefit from the compiler's type checks you'll have to enumerate the different cases.