问题描述
我编写了用于许多操作的 JSP.它有一个参数链接
I have written JSP that I used with many actions. It has a link with parameters
链接:
<s:a namespace="/some" action="view"> <s:param name="purpose" value="%{purpose}"/> <s:param name="type" value="%{type}"/> <s:property value="%{name}"/> </s:a>
动作类:
public class ViewAction extends ActionSupport { private Long purpose; private Long type; private String name; public Long getPurpose() { return purpose; } public void setPurpose(Long purpose) { this.purpose = purpose; } public Long getType() { return type; } public void setType(Long type) { this.type = type; } public String getName() { return name; } public void setName(String name) { this.name = name; } }
通常我会初始化两个参数,但有时一个参数是null.所以,链接是用 href 生成的,比如
Usually I initialize both parameters, but sometimes one parameter is null. So, the link is generated with href like
/context/some/view?purpose=1&type=
但我想删除 &type=
我尝试了 Param 示例.
<s:a namespace="/some" action="view"> <s:param name="purpose" value="%{purpose}"/> <s:param name="type" value="%{type}"/> <s:property value="%{name}"/> <s:param name="suppressEmptyParameters" value="true"/> </s:a>
但是没用
我也试过了
<s:a namespace="/some" action="view"> <s:param name="purpose" value="%{purpose}"/> <s:param name="type" value="%{type}" suppressEmptyParameters="true"/> <s:property value="%{name}"/> </s:a>
我得到了
java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String at org.apache.struts2.components.Param.end(Param.java:129) at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
如何解决这个问题?
推荐答案
那行 <s:param name="suppressEmptyParameters" value="true"/> 没有意义,并且应该从 <s:param> 文档中删除.
Well that line <s:param name="suppressEmptyParameters" value="true"/> doesn't make sense, and it should be removed from the <s:param> docs.
<s:param name="type" value="%{type}" suppressEmptyParameters="true"/> 是抑制空参数的正确方法,但它不起作用由于错误 WW-4275 而不是 String-s.
The <s:param name="type" value="%{type}" suppressEmptyParameters="true"/> is correct way of suppressing empty parameters and it isn't working with not String-s because of the bug WW-4275.
同时,在下一个版本发布之前,您可以使用toString()方法来避免ClassCastException异常.
Meanwhile, until the next version is released, you can use toString() method to avoid ClassCastException exception.
<s:param name="type" value="type.toString()" suppressEmptyParameters="true"/>