struts標籤取值
在struts標籤中,我們的el表達式,${}是不能使用的
package com.asiainfo.struts.action;
import java.util.ArrayList;
import java.util.List;
import com.asiainfo.struts.pojo.Group;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ModelDriven;
public class GroupAction implements ModelDriven<Group>{
private String username;
private Group group;
public Group getGroup() {
return group;
}
public void setGroup(Group group) {
this.group = group;
}
public String login() {
List<String> list= new ArrayList<String>();
list.add("football");
list.add("basketball");
group.setHoppy(list);
group.setGroupName("曾孟良");
group.setGroupNum(22);
ActionContext.getContext().put("username", "你好");
return "success";
}
public Group getModel() {
if(group==null) group=new Group();
return group;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
}
如下
<s:form action="Group_modify.action" method="get">
<s:textfield label="組名" name="${groupName}"></s:textfield>
<s:textfield label="組人數" name="groupNum"></s:textfield>
<s:checkboxlist label="興趣" name="hoppy" list="#{'basketball':'足球','football':'籃球','pingpong':'乒乓球'}" listKey="key" listValue="value" value="hoppy"></s:checkboxlist>
<s:radio label="性別" list="#{'0':'男','1':'女' }"></s:radio>
<s:submit value="登陸"></s:submit>
</s:form>
${groupName} 就報錯了,According to TLD or attribute directive in tag file, attribute name does not accept any expressions<s:form action="Group_modify.action" method="get">
<s:textfield label="組名" name="groupName"></s:textfield>
<s:textfield label="組人數" name="groupNum"></s:textfield>
<s:checkboxlist label="興趣" name="hoppy" list="#{'basketball':'足球','football':'籃球','pingpong':'乒乓球'}" listKey="key" listValue="value" value="hoppy"></s:checkboxlist>
<s:radio label="性別" list="#{'0':'男','1':'女' }"></s:radio>
<s:submit value="登陸"></s:submit>
</s:form>
測試結果
在struts中,取值有兩種,一種是從compoundroot中取值,一種是從actionContext中取值,如果是compoundroot可以直接取值爲key,如果是actionContext中需要加上#key
我這裏action實現了ModelDrive,就將group加入到root中
如圖:root 值棧
在root中的值,是可以直接用el表達式取值,如${groupName},但是如果在struts標籤中,取值就需要直接groupName,或者%{groupName} 或者#groupName,不能直接用el表達式
#groupName 會在actionContext中找,找不到就返回空
${groupName},groupName 會先在root中找,找不到,就到actionContext中找
在struts的標籤中,%{} 會現在root中,找不到就到actionContext中找
如果在root和actionContext中都存在 %{} 會以root中的取值爲主