2. 程式人生 > >Hibernate 列表查詢操作提示存在迴圈，JSON資料轉換異常

Hibernate 列表查詢操作提示存在迴圈，JSON資料轉換異常

阿新 • • 發佈：2019-02-06

執行列表查詢（Subarea）列印的SQL語句：

Hibernate: 
    select
        region0_.id as id1_1_,
        region0_.province as province2_1_,
        region0_.city as city3_1_,
        region0_.district as district4_1_,
        region0_.postcode as postcode5_1_,
        region0_.shortcode as shortcod6_1_,
        region0_.citycode as citycode7_1_ 
    from
        bc_region region0_
 

Hibernate: 
    select
        count(*) as y0_ 
    from
        bc_subarea this_
Hibernate: 
    select
        this_.id as id1_3_0_,
        this_.decidedzone_id as decidedz2_3_0_,
        this_.region_id as region_i3_3_0_,
        this_.addresskey as addressk4_3_0_,
        this_.startnum as startnum5_3_0_,
        this_.endnum as endnum6_3_0_,
        this_.single as single7_3_0_,
        this_.position as position8_3_0_ 
    from
        bc_subarea this_ limit ?
Hibernate: 
    select
        region0_.id as id1_1_0_,
        region0_.province as province2_1_0_,
        region0_.city as city3_1_0_,
        region0_.district as district4_1_0_,
        region0_.postcode as postcode5_1_0_,
        region0_.shortcode as shortcod6_1_0_,
        region0_.citycode as citycode7_1_0_ 
    from
        bc_region region0_ 
    where
        region0_.id=?
控制檯打印出來了4條SQL語句，其中查詢了兩次Region類對應的表，可能是錯誤所指的迴圈。

Region類和Subarea類是一對多的關係，兩個類屬性如下圖：

區域屬性 分割槽屬性

錯誤資訊：

22:20:56,738  INFO JSONObject:769 - Property 'autoClear' of class org.hibernate.internal.SessionImpl has no read method. SKIPPED

22:20:59,961 ERROR DefaultDispatcherErrorHandler:42 - Exception occurred during processing request: There is a cycle in the hierarchy!


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:657)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONArray._processValue(JSONArray.java:2513)
at net.sf.json.JSONArray.processValue(JSONArray.java:2538)
at net.sf.json.JSONArray.addValue(JSONArray.java:2525)
at net.sf.json.JSONArray._fromCollection(JSONArray.java:1056)
at net.sf.json.JSONArray.fromObject(JSONArray.java:123)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:240)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject._fromMap(JSONObject.java:1168)
at net.sf.json.JSONObject.fromObject(JSONObject.java:163)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
at net.sf.json.JSONArray._processValue(JSONArray.java:2513)
at net.sf.json.JSONArray.processValue(JSONArray.java:2538)
at net.sf.json.JSONArray.addValue(JSONArray.java:2525)
at net.sf.json.JSONArray._fromCollection(JSONArray.java:1056)
at net.sf.json.JSONArray.fromObject(JSONArray.java:123)
at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:240)
at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
at com.dengtuzi.bos.web.action.base.BaseAction.object2Json(BaseAction.java:67)
at com.dengtuzi.bos.web.action.SubareaAction.pageQuery(SubareaAction.java:69)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:891)
at ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1293)
at ognl.ObjectMethodAccessor.callMethod(ObjectMethodAccessor.java:68)
at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethodWithDebugInfo(XWorkMethodAccessor.java:117)
at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethod(XWorkMethodAccessor.java:108)
at ognl.OgnlRuntime.callMethod(OgnlRuntime.java:1369)
at ognl.ASTMethod.getValueBody(ASTMethod.java:90)
at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
at ognl.SimpleNode.getValue(SimpleNode.java:258)
at ognl.Ognl.getValue(Ognl.java:494)
at ognl.Ognl.getValue(Ognl.java:458)
at com.opensymphony.xwork2.ognl.OgnlUtil$2.execute(OgnlUtil.java:309)
at com.opensymphony.xwork2.ognl.OgnlUtil.compileAndExecute(OgnlUtil.java:340)
at com.opensymphony.xwork2.ognl.OgnlUtil.getValue(OgnlUtil.java:307)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:423)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:287)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:250)
at org.apache.struts2.interceptor.DeprecationInterceptor.intercept(DeprecationInterceptor.java:41)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:76)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at org.apache.struts2.interceptor.DateTextFieldInterceptor.intercept(DateTextFieldInterceptor.java:125)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:253)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:139)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at com.dengtuzi.bos.web.interceptor.BOSLoginIntercepter.doIntercept(BOSLoginIntercepter.java:28)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:564)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.orm.hibernate5.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:151)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

分析錯誤資訊，發現查詢到分割槽資訊後，將資料轉成JSON的時候發生。

呼叫方法程式碼：

//轉json資料寫回前端
object2Json(pageBean, new String[]{"currentPage","detachedCriteria","pageSize","subareas","decidedzone"});
object2Json方法： 
	public void object2Json(Object object,String[] excludes){
		//設定忽略欄位，將pageBean轉為json物件寫回給前端
		JsonConfig config = new JsonConfig();
		config.setExcludes(excludes);
		//靜態方法轉換成json物件
		String json = JSONObject.fromObject(object, config).toString();
		//設定文字格式
		ServletActionContext.getResponse().setContentType("text/json;charset=utf-8");
		try {
			//將資料返回給前端
			ServletActionContext.getResponse().getWriter().println(json);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

在呼叫object2Json方法處下斷點，開始除錯。發現pageBean中Rows中Region的值是代理物件，根據Hibernate預設的延遲載入機制，Subarea關聯的Region屬性在查詢時並沒有真正獲取Region物件的資料，只有在Region物件的資料使用時（執行object2Json方法時）才真正從資料庫中載入它的資料。

Region_of_Subarea

展開region發現下面有一個名為handler的值，這個屬性值並不屬於定義的Region實體類，看值的名字應該是Hibernate用來實現延遲載入的，繼續展開可以看到handler下面還有很多與Region實體類不相關的屬性。各種矛頭指向延遲載入...

handler

為了驗證是否關聯的Region物件資料的延遲載入導致的異常，在轉JSON資料時把region設定為忽略的欄位，然後重新除錯。

object2Json(pageBean, new String[]{"region","currentPage","detachedCriteria","pageSize","subareas","decidedzone"});

這時程式已經正常執行，控制檯列印的SQL語句變為3條：

Hibernate: 
    select
        region0_.id as id1_1_,
        region0_.province as province2_1_,
        region0_.city as city3_1_,
        region0_.district as district4_1_,
        region0_.postcode as postcode5_1_,
        region0_.shortcode as shortcod6_1_,
        region0_.citycode as citycode7_1_ 
    from
        bc_region region0_
Hibernate: 
    select
        count(*) as y0_ 
    from
        bc_subarea this_
Hibernate: 
    select
        this_.id as id1_3_0_,
        this_.decidedzone_id as decidedz2_3_0_,
        this_.region_id as region_i3_3_0_,
        this_.addresskey as addressk4_3_0_,
        this_.startnum as startnum5_3_0_,
        this_.endnum as endnum6_3_0_,
        this_.single as single7_3_0_,
        this_.position as position8_3_0_ 
    from
        bc_subarea this_ limit ?

既然是Subarea單向關聯關聯的Region類延遲載入導致的問題，那問題就很好解決了，在Subarea的對映檔案中，名為"region"的多對一(many-to-one)標籤中設定關閉延遲載入(lazy="false")，問題解決。 
 <many-to-one lazy="false" name="region" class="Region" >
            <column name="region_id" length="32" />
 </many-to-one>


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