struts2通过action返回json对象

package com.mz.action;
import com.mz.entity.User;
import com.opensymphony.xwork2.ActionSupport;
public class JsonAction extends ActionSupport{
private User user;
public String execute() {
user = new User();
user.setId(123);
user.setUsername("Irasel");
return SUCCESS;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}

<!-- 配置一个返回json字符串的action -->
<package name="resultJson" namespace="/" extends="json-default">
<action name="resultJson" class="com.mz.action.JsonAction">
<result name="success" type="json">
<!--root是ognl表达式的一部分不能更换 -->
<param name="root">user</param>
</result>
</action>
</package>