Struts2系列_#attr.xxxx
attr是struts2添加到值棧的上下文取的一個Map(org.apache.struts2.util.AttributeMap)
這個attr包含4個作用域:
A Map that holds 4 levels of scope.
The scopes are the ones known in the web world.:
Page scope
Request scope
Session scope
Application scope
Dispatcher.java struts2在執行action之前預設放到上下文的 ActionContext
Java代碼
// helpers to get access to request/session/application scope
extraContext.put("request", requestMap);
extraContext.put("session", sessionMap);
extraContext.put("application", applicationMap);
extraContext.put("parameters", parameterMap);
AttributeMap attrMap = new AttributeMap(extraContext);
extraContext.put("attr", attrMap);
按照這個順序查找屬性,順序是page—>request—–>session—->application;
也就是說通過ActionContext.getContext.get(“attr”) 是可以擷取的到的。
attr 是通過ognl表達式,用于通路上下文資料的。