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07 Feb 2009 Comments

出现net.sf.json.JSONException: There is a cycle in the hierarchy异常的解决办法

因为项目中使用了AJAX技术,JAR包为:json-lib.jar,?在开发过程中遇到了一个JSON-LIB和Hibernate有关的问题:

net.sf.json.JSONException: There is a cycle in the hierarchy!

at net.sf.json.util.CycleDetectionStrategy$StrictCycleDetectionStrategy.handleRepeatedReferenceAsObject(CycleDetectionStrategy.java:97)
at net.sf.json.JSONObject._fromBean(JSONObject.java:857)
at net.sf.json.JSONObject.fromObject(JSONObject.java:192)
at net.sf.json.JSONObject._processValue(JSONObject.java:2774)
at net.sf.json.JSONObject._setInternal(JSONObject.java:2798)
at net.sf.json.JSONObject.setValue(JSONObject.java:1507)
at net.sf.json.JSONObject._fromBean(JSONObject.java:940)
at net.sf.json.JSONObject.fromObject(JSONObject.java:192)
at net.sf.json.JSONObject._processValue(JSONObject.java:2774)
at net.sf.json.JSONObject._setInternal(JSONObject.java:2798)
at net.sf.json.JSONObject.setValue(JSONObject.java:1507)
at net.sf.json.JSONObject._fromBean(JSONObject.java:940)
at net.sf.json.JSONObject.fromObject(JSONObject.java:192)
at net.sf.json.JSONObject._processValue(JSONObject.java:2774)
at net.sf.json.JSONObject._setInternal(JSONObject.java:2798)
at net.sf.json.JSONObject.setValue(JSONObject.java:1507)
at net.sf.json.JSONObject._fromBean(JSONObject.java:940)
at net.sf.json.JSONObject.fromObject(JSONObject.java:192)
at net.sf.json.JSONObject._processValue(JSONObject.java:2774)
at net.sf.json.JSONObject._setInternal(JSONObject.java:2798)
at net.sf.json.JSONObject.setValue(JSONObject.java:1507)
at net.sf.json.JSONObject._fromBean(JSONObject.java:940)
at net.sf.json.JSONObject.fromObject(JSONObject.java:192)
at net.yanhl.iouser.action.IOUserAction.loadUser(IOUserAction.java:142)

因为Hibernate中设置了自身关联: Iouser.hbm.xml:




//设置自身关联的组对象

public class GroupRelation implements Serializable {

private static final long serialVersionUID = 6202253180943473205L;
private Integer id;// 主键ID
private Integer creatorId;// 创建人
private Date createDate;// 创建日期
private String groupName;// 组名称
private GroupRelation parentGroup;
private Set childGroups = new HashSet();







起初想通过hibernate来解决问题,就是想过滤掉自身关联后来查资料发现不可能实现,最后找到通过JSON-LIB来过滤关联的集合属性,代码如下:

JsonConfig config = new JsonConfig();
config.setJsonPropertyFilter(new PropertyFilter(){
    public boolean apply(Object source, String name, Object value) {
        if(name.equals("parentGroup") || name.equals("childGroups")) {
            return true;
        } else {
            return false;
        }
    }
});
Iouser user = (Iouser) getBaseManager().get(Iouser.class, iouserId);
JSONObject jsonObject = JSONObject.fromObject(user, config);

当JSON-LIB解析JAVABEAN时过滤掉parentGroup、childGroups这两个属性,重新启动服务,pass

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