Draw a dependency relationship between two classes, or between a class and an interface, to show that the client class depends on the supplier class/interface to provide certain services, such as:
The client class accesses a value (constant or variable) defined in the supplier class/interface.（訪問一個屬性值）
Operations of the client class invoke operations of the supplier class/interface.（訪問一個方法）
Operations of the client class have signatures whose return class or arguments are instances of the supplier class/interface.（返回值或者參數是一個被依賴者實例）
A dependency relationship is a dotted line with an arrowhead at one end:The arrowhead points to the supplier class.（是一條帶箭頭的虛線）
2，Association Relationship
An association provides a pathway for communication. The communication can be between use cases and actors, between two classes or between a class and an interface.
Associations are the most general of all relationships and consequentially the most semantically weak. If two objects are usually considered independently, the relationship is an association