利用JsonConfig消除JSON转换出现双向关联循环问题

今天在利用JSONArray.fromObject把对象转成JSON的时候，总是报如下错误：
2011-10-10 13:52:25 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet default threw exception
java.lang.IllegalStateException
at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:407)
at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:801)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:519)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)


百思不得其解，把对象一一遍历打印出后，发现原来是多个多想之间存在双向关联，再转成JSON的过程中，出现死循环。如下

@OneToMany(mappedBy="customer",cascade=CascadeType.PERSIST,fetch=FetchType.LAZY)
	private List<OrderManage> orderManageList; //关于订单管理 by 2011-09-19]

	@OneToMany(mappedBy="consumersCust",fetch=FetchType.EAGER)
	private Set<Consumers> consumers = new HashSet<Consumers>();//商机

利用JsonConfig解决剔除掉关联字段，解决了此问题。

		JsonConfig config = new JsonConfig();   
	    //排除关联对象属性，排除日期两个属性   
	    config.setExcludes(new String[]{"birthday","idcard"});  
	    config.setJsonPropertyFilter(new PropertyFilter(){ 
	    	public boolean apply(Object source, String name, Object value) { 
	    	if(name.equals("linkMans")||name.equals("consumers")||name.equals("orderManageList")) { 
	    		return true; 
	    	} else { 
	    		return false; 
	    	} 
	    	} 
	    }); 
              //JsonConfig 还提供了JSON转换功能，也能方便
	    config.registerJsonValueProcessor(java.util.Date.class, new JsonValueProcessorDate());