A, EL expressions 11 built-in objects :
Wherein // is the type Map 10; pageContext object is the last one;
| pageScope |
requestScope |
sessionScope |
applicationScope |
| param |
paramValues |
header |
headerValues |
| Initfrm |
cookie |
pageContext |
|
Second, the domain related objects:
（1）pageScope：${pageScope.name}等同与pageContext.getAttribute(“name”)；
（2）requestScope：${requestScope.name}等同与request.getAttribute(“name”)；
（3）sessionScoep： ${sessionScope.name}等同与session.getAttribute(“name”)；
（4）applicationScope：${applicationScope.name}等同与application.getAttribute(“name”)；
Third, the global find: $ { name };
In turn represents pageScope, requesScopet, sessionScope, appliationScope find four domain names for the name of the property;
$ {Name.value} // if the object is acquired, the attribute can be directly getting a property value point within the object, but only if there get method;
// get the array: $ {name [ I ] .Value};
Fourth, the operator:
1. arithmetic: + - * /%
2. Relationship operations:> <!> = <= = ==
3. logic operations: && ||!
4. Analyzing:
(1) Analyzing the empty: $ {empty List } ; // List is empty;
(2) determining non-empty: $ {Not empty List } ; // if List is not empty;
// Example: $ {80> 90}; $ {80 + 90};
V. element attributes related objects:
( . 1 ) $ { . Param name }: the same request.getParameter (String name) method;
( 2 ) $ { paramValues. Name }: the request. Same getParameterValues (String name) method;
// using EL -time expressions acquisition parameters, if not obtain return an empty string, not null ;
Sixth, the request header related objects:
(. 1) {$} header.Host : acquiring request header; the Map <String, String> type;
(2) {$} headerValues.Host : multi-value acquisition request header; the Map <String, String []> type;
Seven objects related initialization parameters: the web.xml file <context-param> parameters;
(1) $ {initParam.name}: Get the name name of parameter values;
(2) $ {initParam [ 'name']}: single quotation marks in the table acquired, different wording;
// If the parameter name contains _ underscore, must be used (2) under standard methods, other times random;
Eight, Cookie parameters:
// return to Map <String, Cookie> type, where key is the name of Cookie, Cookie and the value is the object itself.
(1) $ {cookie.name.name}: get the name of the cookie named name; // so stupid;
(2) $ {cookie.name.value}: obtain the value of the cookie named name;
Nine, pageContext objects:
Used to obtain additional eight jsp objects;
// return type PageContext; may be used getXXX () methods:
