Let's look back at UML.

Let's look back at UML.
Recently, I was preparing for the soft test. UML is one of the test sites. I heard that the master has a high score in the afternoon, so I will summarize the UML learning. I learned how to use UML as early as last year, please check out my series of blogs and understand UML more and more deeply. UML is like the blood and engineers of software design. Without it, software design is just a piece of paper.

The explicit sequence diagram, use case diagram, and package icon in the figure are marked as red. To put it simply, their dependencies are: Package Diagram-> class diagram-> use case diagram-> time sequence diagram, because these three diagrams play a very important role in our software development process, I will explain them below.

The first part of a software design is to understand the user's needs, and then design the database. After the database is built, the package graph is created. It is equivalent to a macro framework, it describes the basic architecture of the entire code implementation. For the data room charging system, we use Layer 7, including the interface, appearance, business logic layer, abstract factory, interface, and data layer, sqlhelper: for example:


So what is the relationship between a package chart and a class chart?
Each package contains the class corresponding to the functions to be executed by the package. For example, the interface layer contains all form forms, and these forms are classes, the form presented by each class is an object. The function of a package is to reclassify classes of different functions so that the call relationship between classes is clear.
Next let's take a look at the role of a class diagram: (taking the class diagram in The BLL package as an example)

This is one of the classes in the package diagram, which includes variables (attributes) and methods (events)

Because the relationship between the three graphs has been mentioned above, the following is the use case diagram and the sequence diagram. With the foundation of the class diagram and a sufficient understanding of the business, the use case diagram can be easily drawn, what is a Use Case chart? It is composed of roles (such as students), functions (such as querying computer records), and relationships. Generally, a use case corresponds to a function block, for example, a data center charging system ):

"Login" is a use case (function). The following figure shows the sequence diagram. It is obvious that the sequence diagram is used to describe the time sequence of a function execution, therefore, it is called a time sequence diagram. You only need to drag the class diagram in the class diagram to the time sequence diagram, provided that the call relationship between the package and the package is not violated. For example, to conform to the call relationship between packages:

UML learning is only part of the soft test, but the soft test is not the ultimate goal, but is constantly enriched and robust in both the soft test, the self test, and the grade test, and learning does not require a smooth learning, because it is repeated, everything is nothing, just do it!