Panda.Ioc - How to define an object

For Panda Ioc, its configuration file is a nested “name-value pair collection”, or a collection of Maps. In fact, it first parses the entire configuration file into a Map.

If a Map contains only the following keys, it is considered a strictly defined inject object:

Keyword	Description
type	object type
singleton	singleton or not
scope	object life cycle
events	event listeners
args	constructor parameters
fields	field settings
factory	factory method

Otherwise, the Map is considered to be an anonymous object that declares each field of the object.

Anonymous object

If a field’s value is such a “Strictly defined Map” as above, then it is naturally considered to be an anonymous object.

Because this object has no name, you cannot obtain it directly through the Ioc interface. It is hidden in a field of an object.

The anonymous object is not singleton, even if singleton: true is declared. If its host is a singleton object, it will naturally only be created once. Otherwise, it will be created each time the host is created.

JSON configuration file:

	tom : {
		name : 'Tom',
		// Note: here, the 'friend' field directly declares another object
		friend : {
			type : 'panda.demo.ioc.json.Pet',
			fields : {
				name : 'Jerry'
			}
		}
	}

Calling source code:

	Ioc ioc = new DefaultIoc(new JsonLoader("panda/demo/ioc/json/Pets.json"));
	Pet pet = ioc.get(Pet.class, "tom");
	System.out.println(pet.getFriend().getName());
	ioc.depose();

Output:

Jerry

Factory method

Syntax 1 (full_class_name@method_name):

{
	type : "panda.demo.ioc.Pet",
	args : [ "Tom" ],
	factory: "com.my.PetFactory@create"
}

Where com.my.PetFactory is the full class name of the factory class, create is the factory method, and its parameter is “Tom”.

Syntax 2 (#ioc_object_name.method_name):

{
	type : "panda.demo.ioc.Pet",
	args : [ "Tom" ],
	factory: "#PetFactory.create"
}

Where PetFactory is the name of the Ioc object, create is the factory method and its parameter is “Tom”.

Syntax 3 (${el_expression}):

{
	type : "panda.demo.ioc.Pet",
	args : [ "Tom" ],
	factory: "${'com.my.PetFactory'@create()}"
}

Where ${‘com.my.PetFactory’@create()} is an EL expression. The method of writing an EL expression can refer to [here] (inject_en.md#el%20expression).

Note that the EL expression ignores the parameter setting args : [ “Tom” ].

For a more detailed description, please refer to EL Expression.

Life cycle

The default scope is the app, which coexists with the ioc container. Additional scopes are request and session or customized scope. The IOC itself will almost never use a scope other than the app. The MVC module will use the request and session scope. In general, you do not need to set the scope value.