Introduction to builder pattern (builder pattern) of Java design pattern

Builder pattern definition: separate the construction of a complex object from its representation, so that the same construction process can create different representations.

The builder pattern is to create a complex object step by step. It allows users to build complex objects only by specifying their types and contents. The user does not know the specific internal construction details. The builder pattern is very similar to the abstract factory pattern. The subtle differences can only be realized in repeated use.

Why use builder mode

Is to decouple the process of building complex objects from its components. Note: it is the decoupling process and components.

Because a complex object not only has a large number of components, such as a car, but also has many components: wheels, steering wheel, engine, various small parts, etc. there are many components, but far more than these. How to assemble these components into a car is also a complex assembly process (good assembly technology is required), The builder pattern is to separate the part from the assembly process.

How to use builder mode

Firstly, it is assumed that a complex object is composed of multiple components. The builder pattern separates the creation of complex objects from the creation of components, which are represented by builder class and director class respectively.

First, you need an interface that defines how to create the various parts of a complex object: