struts2返回json数据出错

2014-4-18 8:57:17 com.opensymphony.xwork2.util.logging.commons.CommonsLogger error
严重: Dispatcher initialization failed
Unable to load configuration. - action - file:/D:/Program%20Files/Java/apache-tomcat-7.0.53/webapps/perform/WEB-INF/classes/json.xml:12:92
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:58)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:374)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:418)
at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:69)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:279)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:260)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:105)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4809)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5485)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:632)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1229)
at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1875)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
<global-results>
<result name="result" type="json">
<param name="root">result<裤燃/param>
</result>
<result name="胡皮虚error">/resource/jsp/error.jsp</result>
</global-results>

action:
private String result;

public String xxxx(){
JsonObject json=new JsonObject ();
result=json.toString();

return "result";

}

我是这样配置的。你要粘贴代码才能握数给你定位问题。光看错误不是非常明显。
struts2配置返回类型为json了么。