1, to determine the functional requirements of the system: requirements analysis document is an important basis for functional analysis of the system, which describes in detail the functional requirements of the system and performance requirements. In the class diagram model of the analysis and design, according to the functional requirements of the requirements document, to determine what classes are needed in the system and the relationship between them, so as to ensure that the system can meet the user's needs.
2. Determine the structural requirements of the system: the requirements analysis document not only includes the functional requirements of the system, but also includes the structural requirements of the system, such as the performance of the system, maintainability, scalability and so on. When analyzing and designing the class diagram model, you need to determine the attributes and methods of each class in the system according to the structural requirements in the requirements document, so as to ensure that the system has good performance, maintainability and scalability.