table of Contents
First, why use the builder pattern
Fourth, the advantages of model
First, why use the builder pattern
Builder and its mode can be set member
mounted separate process, step by step, to create a complex object
. The user need only specify a complex
object type of the object can be obtained, without having to know the specific details of its internal structure.
Second, the schema definition
Builder mode
(the Pattern Builder)
: The
structure of a complex object is
built and it means isolated
, so
constructed the same process can create different
representations
.
The builder pattern is
a step by step to create a complex object
, it allows
you to build their families only by specifying the type and content of complex objects,
users do not need to know specific details of the construction. The builder pattern belong to the
object creation schema. Depending on the Chinese translation of the builder pattern and
may be known as a generator mode.
Third, the model structure
Builders mode includes the following roles:
•
Builder
: abstract Builder
•
ConcreteBuilder
: concrete builder
•
Director: director (the one hand, it
isolates the customer and production
process
; on the other hand it is
responsible for controlling the generation process of the product
)
•
Product
: Product roles
Fourth, the advantages of model
•
In the builder mode,
the client does not have to know the details of the internal composition of the product, the product itself and the process of creating the product decoupled so that the same creation process can create different product objects
.
•
each specific builders are relatively independent, regardless of other specific builder, so it can easily replace specific builder or add new concrete builder,
users use different specific builder can get a different product target
.
•
can more finely control the product creation process.
The step of creating the complex decomposition products in different ways, so that the creation of clearer and more easy to use program to control the creation process.
•
Add a new concrete builder without modifying the original class library code to facilitate the expansion class commander for abstract builder class programming system, in line with "the principle of opening and closing."
Fifth, the mode shortcomings
•
the builder pattern created products generally have more in common, which is part of similar,
if the difference between a great product is not suitable to use the builder pattern,
Its use is subject to certain limitations
.
•
If the internal changes in product complexity, may cause a lot of need to define concrete builder classes to implement this change, cause the system to become very large
.
Sixth, for the environment
•
need to generate products and objects have complex internal structures
, these products often contain more than one member objects attributes.
•
properties need to generate products interdependent objects, you need to specify the order of their generation
.
•
Create a process to create objects independent of the object's class
. In the builder pattern introduced in the director category, the commander creation process encapsulated in the class, rather than in the builders.
•
isolation create and use complex objects, and makes the same creation process can create different products
