1. effect
- Used in the analysis and design phase of object-oriented software development , Describe the static structure of the system .
- Describe classes and classes 、 Classes and interfaces 、 Static structure and relationship between interfaces , Describe the structural design of the system . The most basic element ： class 、 Interface .
- General conceptual modeling for applications 、 Detailed modeling 、 Data modeling , Convert the model into programming code .
- Class diagram is an important model basis for system coding and testing .
2. Elements
- package （package）
- class （class）
- Interface （interface）
- Relationship （relation）
- The signal （signal）
- data type （data type）
- The original type （primitive type）
- enumeration （enumeration）
3. Range properties
- +：public
- #：protected
- -：private
- ~：package
4. Relationship
4.1 relation （association）
Ownership , The owner can know the properties and methods of the owner . The owner is the attribute of the owner . Association is divided into one-way Association （unidirectional association） And two-way Association （bidirectional association）.
litchi ：
4.2 rely on （dependency）
Use relationship . The user needs some properties and methods of the user .
litchi ：
4.3 generalization （generalization）
Inheritance relationships . Make the successor （ Subclass ） Have the inheritee （ Parent class ） Properties and methods of .
litchi ：
4.4 polymerization （aggregation）
Describe the relationship between the whole and the parts , Part can exist independently of the whole .
litchi ：
4.4 Combine （composition）
Describe the relationship between the whole and the parts , The part cannot exist independently of the whole .
litchi ：
4.5 Realization （realization）
The methods of the class reflect the behavior of the interface .
litchi ：
5. Robustness（ expand ）
The border （boundary）
Entity （entity）
control （control）
6. Litchi chinensis
![my. Binlog startup failure caused by the difference between [mysql] and [mysqld] in CNF](/img/bd/a28e74654c7821b3a9cd9260d2e399.png)
