org.apache.struts2.json.JSONWriter can not access a member of class

转自:http://www.cnblogs.com/xiaoyaorensheng/archive/2013/01/02/2842302.html 

偶遇一个问题：org.apache.struts2.json.JSONWriter can not access a member of class 
org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper 
with modifiers "public"。困扰了半天，找到了解决方案，写写自己的一些理解。 

action代码： 


1 package edu.bjfu.action; 
2 
3 import java.util.ArrayList; 
4 import java.util.List; 
5 
6 import javax.annotation.Resource; 
7 
8 import org.apache.struts2.json.annotations.JSON; 
9 
10 
11 import com.opensymphony.xwork2.ActionSupport; 
12 
13 import edu.bjfu.entity.Authority; 
14 import edu.bjfu.service.AuthorityService; 
15 
16 public class AuthoritiesAction extends ActionSupport{ 
17     private AuthorityService authorityService; 
18     private List<Authority> authorities; 
19 
20     public List<Authority> getAuthorities() { 
21         return authorities; 
22     } 
23 
24     public void setAuthorities(List<Authority> authorities) { 
25         this.authorities = authorities; 
26     } 
27     public AuthorityService getAuthorityService() { 
28         return authorityService; 
29     } 
30 
31     @Resource(name="authorityService") 
32     public void setAuthorityService(AuthorityService authorityService) { 
33         this.authorityService = authorityService; 
34     } 
35     
36     public String execute() throws Exception { 
37         authorities=authorityService.getAllAuthorities(); 
38         return SUCCESS; 
39     } 
40     
41 } 



配置文件代码： 

1 <package name="super_admin" extends="json-default" namespace="/superadmin"> 
2         <action name="allAuthorities" class="edu.bjfu.action.AuthoritiesAction"> 
3             <result type="json"></result> 
4         </action> 
5 </package> 
ajax交互代码： 


1 $(function(){ 
2     $.post("superadmin/allAuthorities?dt="+new Date().getTime(), 
3         function(data){ 
4             $("#authority").empty(); 
5             var json = eval(data); 
6             for(var i=0;i<json.length;i++){ 
7                 $("#authority").append("<option value='"+json[i].authorityId+"'>"+json[i].authorityName+"</option>"); 
8             } 
9         },"json") 
10 }) 

这样每次在交互的时候就会发生以上错误。 

主要原因：struts会将action中定义的一些变量序列化转换成json格式，需要调用对象的一系列get方法（例子中调用authorityService和authorities的get方法），并调用以上两个变量的成员变量的get方法将其内容组成json格式。但是在序列化authorityService时，由于其成员变量中含有含有接口所以会报错。 

解决方案： 

1）修改配置文件：指定序列化的根节点，这样data就是从authorities的根节点以下的数据，不需要用data.authorities 

1     <package name="super_admin" extends="json-default" namespace="/superadmin"> 
2         <action name="allAuthorities" class="edu.bjfu.action.AuthoritiesAction"> 
3             <result type="json"><param name="root">authorities</param></result> 
4         </action> 
5     </package> 
2) 修改java代码：让编译器不对authorityService序列化 

1     @JSON(serialize=false) 
2     public AuthorityService getAuthorityService() { 
3         return authorityService; 
4     }