how can i use request parameter in struts2 if tag

问题

i have a link like this :http://localhost:8080/ESA/login.jsp?login=failed in end of above link a set a parameter with name login and value failed.
how i can use this parameter in jsp page with struts if tag. I use following code but it don't work.

<s:if test="%{#parameters.login='failed'}">
    <div class="error">
        <s:text name="user.login.failed"></s:text>
    </div>
</s:if>

回答1:

Try with

<s:if test="%{#parameters.login[0]=='failed'}">

The two problems were in your code:

1. The = sign is an assignment, not equals ==;

2. Parameters are saved in the Map<String, String[]>, so each parameter could have multiple values and accessed by the specifying an index.

   The last option also described here: why doesn't the if tag evaluate params properly.

来源：https://stackoverflow.com/questions/17817767/how-can-i-use-request-parameter-in-struts2-if-tag