package
Concept of package:
Physically a folder
Used to manage classes
The role of the package:
Avoid duplicate class names
Manage classes according to different functions
Control access
Package naming convention:
In the package name, you can use the. Number to distinguish the level of the package; the package name is generally lowercase. The
first level refers to the type of the project, such as com, org, gov, etc., and the
second level refers to the company developed or operated by the project Name, such as: oracle, sun, huawei, etc. The
third level refers to the name of the project, such as: bcms, oa, erp, cms, etc. The
fourth level refers to the name of the project module, such as: bean, action, exception, etc.
Packages can better manage logic-related classes, and can control access rights between different packages.
Import classes from external packages, keyword "import"