Struts2标签的使用总结

1：Description

 

The set tag assigns a value to a variable in a specified scope. It is useful when you wish to assign a variable to a complex expression and then simply reference that variable each time rather than the complex expression. This is useful in both cases: when the complex expression takes time (performance improvement) or is hard to read (code readability improvement).

If the tag is used with body content, the evaluation of the value parameter is omitted. Instead, the String to which the body eveluates is set as value for the scoped variable.

 

The scopes available are as follows :-

• application - the value will be set in application scope according to servlet spec. using the name as its key
• session - the value will be set in session scope according to servlet spec. using the name as key
• request - the value will be set in request scope according to servlet spec. using the name as key
• page - the value will be set in page scope according to servlet sepc. using the name as key
• action - the value will be set in the request scope and Struts' action context using the name as key

 

NOTE:

If no scope is specified, it will default to action scope.

即可以设置五个范围:application, session, request, page, action，每个范围有不同的含义

 

2：Parameters

   

Name       Required      Default       Evaluated    Type        description

   id                 false                                   false                String         Deprecated. Use 'var' instead

   name            false                                    false                String        Deprecated. Use 'var' instead

   scope            false                action          false                String        The scope in which to assign the variable. Can be application, session, request, page, or action.

 

   value          false                                     false               String        The value that is assigned to the variable named name

   var             false                                      false              String         Name used to reference the value pushed into the Value Stack

 

3：例子

<s:set name="personName" value="person.name"/>Hello, <s:property value="#personName"/>. How are you？

使用<s:set name="personName" value="person.name" />来定义一个personName的变量，该变量的值为person.name属性的值，

并用<s:property value="#personName"/> 来访问该变量的值

<li>bean, 定义bean，并使用param来设定新的属性值:
         <s:bean name="com.capinfotech.ognl.action.Dog">
            <s:param name="name" value="dongdong" />
         </s:bean>
     </li>
     <li>
          <s:bean name="com.capinfotech.ognl.action.Dog" var="myDog">
             <s:param name="name" value="'mydog'"></s:param>
          </s:bean>
     </li>

第一个<li>里的例子定义一个Dog的对象，该对象的name属性的值为dongdong在ActionContext里对应的值

第二个<li>里的例子定义一个Dog的对象，该对象的name属性的值为mydog

注意：<s:param>里的value的类型为string类型的