El Expression-4

PageContext

PageContext obtain additional information about user requirements or pages.

${pagecontext.request.querystring} Gets the requested argument string

${pagecontext.request.requesturl} Gets the requested URL, but does not include the request's argument string

${pagecontext.request.contextpath} The name of the Web application of the service

${pagecontext.request.method} Method of getting HTTP (get, POST)

${pagecontext.request.protocol} Get the protocol used (http/1.1, http/1.0)

${pagecontext.request.remoteuser} Get user name

${PAGECONTEXT.REQUEST.REMOTEADDR} Get the IP address of the user

${pagecontext.session.new} to determine if the session is a new

${pagecontext.session.id} Gets the ID of the session

${pagecontext.servletcontext.serverinfo} access to host-side service information

Three, El operator

1. There are five arithmetic operators: + 、-、 * or $,/or div,% or mod

2. There are six relational operators: = = or EQ,! = or NE, < or LT, > or GT, <= or LE, >=, or GE

3. The logical operator has three:&& or an and, | | Or,!, or not

4. There are three other operators: the empty operator, the condition operator, the () operator

The most commonly used expressions:

empty judgment : ${empty Param.name}

ternary operation : ${a? B:C}

arithmetic Operation : ${a* (B+c)}