1. EL syntax and usage
EL(Expression Language)It is to make JSP easier to write.
1、Grammatical structure
${The name attribute value of the domain object}
2、Method of value acquisition
From small to large: page, request, session, application
If it is found, it shows, if it is not found, it continues to look up, and if it is not found in the application, it displays an empty string
If you need to fetch the value of the specified domain scope, you can set the corresponding domain scope (pageScope, requestScope, session Scope, application Scope)
3、Be careful
elExpressions generally operate only on domain objects and are unable to manipulate variables.
Two, EL get parameters
Three. EL- entity class
Four. EL-List container
Five, EL-map set
Six, EL operation
1、The two nonexistent domain object (numeric) is added with a value of 0.
2、A existence (numerical type), a non additive, value being.
3、The addition of non numeric strings will cause errors.
