当我尝试在我的域类上使用Groovy的JsonBuilder类时，我的Grails应用程序及其集成测试抛出了StackOverflowError。我的代码如下所示：
String result = new JsonBuilder(new MyDomainClass())
由于我发现有关JsonBuilder循环自我引用的文章，我将域类简化为几乎没有：
package com.mycompany.myapp.myarea
class MyDomainClass { }
但堆栈溢出仍然重现。这是踢球者。如果我将MyDomainClass的声明移出其正常位置并进入单元测试所在的文件（即将其从包中取出），则JsonBuilder可以工作。
下面的堆栈跟踪。这里有什么帮助吗？
谢谢， BGU
java.lang.StackOverflowError
at java.security.AccessController.doPrivileged(Native Method)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.createCallStaticSite(CallSiteArray.java:62)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.createCallSite(CallSiteArray.java:159)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
at java_lang_Class$isArray.call(Unknown Source)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:135)
at groovy.json.JsonOutput$toJson.callStatic(Unknown Source)
at groovy.json.JsonOutput$_toJson_closure2.doCall(JsonOutput.groovy:158)
at sun.reflect.GeneratedMethodAccessor974.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1082)
at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1106)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:906)
at groovy.lang.Closure.call(Closure.java:412)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.callClosureForMapEntry(DefaultGroovyMethods.java:3870)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2426)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2443)
at org.codehaus.groovy.runtime.dgm$61.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:154)
at groovy.json.JsonOutput$toJson$0.callStatic(Unknown Source)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:146)
at groovy.json.JsonOutput$toJson.callStatic(Unknown Source)
at groovy.json.JsonOutput$_toJson_closure1.doCall(JsonOutput.groovy:138)
at sun.reflect.GeneratedMethodAccessor978.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1082)
at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1106)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:906)
at groovy.lang.Closure.call(Closure.java:412)
at groovy.lang.Closure.call(Closure.java:425)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2157)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2128)
at org.codehaus.groovy.runtime.dgm$59.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:138)
at groovy.json.JsonOutput$toJson.callStatic(Unknown Source)
at groovy.json.JsonOutput$_toJson_closure2.doCall(JsonOutput.groovy:158)
at sun.reflect.GeneratedMethodAccessor974.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1082)
at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1106)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:906)
at groovy.lang.Closure.call(Closure.java:412)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.callClosureForMapEntry(DefaultGroovyMethods.java:3870)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2426)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2443)
at org.codehaus.groovy.runtime.dgm$61.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:154)
at groovy.json.JsonOutput$toJson$0.callStatic(Unknown Source)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:146)
at groovy.json.JsonOutput$toJson.callStatic(Unknown Source)
at groovy.json.JsonOutput$_toJson_closure1.doCall(JsonOutput.groovy:138)
at sun.reflect.GeneratedMethodAccessor978.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1082)
at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1106)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:906)
at groovy.lang.Closure.call(Closure.java:412)
at groovy.lang.Closure.call(Closure.java:425)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2157)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2128)
at org.codehaus.groovy.runtime.dgm$59.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:138)
at groovy.json.JsonOutput$toJson.callStatic(Unknown Source)
at groovy.json.JsonOutput$_toJson_closure2.doCall(JsonOutput.groovy:158)
at sun.reflect.GeneratedMethodAccessor974.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1082)
at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1106)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:906)
at groovy.lang.Closure.call(Closure.java:412)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.callClosureForMapEntry(DefaultGroovyMethods.java:3870)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2426)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2443)
at org.codehaus.groovy.runtime.dgm$61.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:154)
at groovy.json.JsonOutput$toJson$0.callStatic(Unknown Source)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:146)
at groovy.json.JsonOutput$toJson.callStatic(Unknown Source)
at groovy.json.JsonOutput$_toJson_closure1.doCall(JsonOutput.groovy:138)
at sun.reflect.GeneratedMethodAccessor978.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1082)
at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1106)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:906)
at groovy.lang.Closure.call(Closure.java:412)
at groovy.lang.Closure.call(Closure.java:425)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2157)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2128)
at org.codehaus.groovy.runtime.dgm$59.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at groovy.json.JsonOutput.toJson(JsonOutput.groovy:138)
at groovy.json.JsonOutput$toJson.callStatic(Unknown Source)
at groovy.json.JsonOutput$_toJson_closure2.doCall(JsonOutput.groovy:158)
at sun.reflect.GeneratedMethodAccessor974.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1082)
at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1106)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:906)
at groovy.lang.Closure.call(Closure.java:412)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.callClosureForMapEntry(DefaultGroovyMethods.java:3870)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2426)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.collect(DefaultGroovyMethods.java:2443)
at org.codehaus.groovy.runtime.dgm$61.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)...
答案 0 :(得分：1)
我稍微进入了代码，JsonBuilder有许多类型检查来决定如何写入对象。如果是域类，则它与Iterable匹配。然后它尝试循环并编写每个项目等。
奇怪的是，在将对象转换为next之后Iterable会返回对象本身....导致无限循环。
如果我写下面的内容（在没有显式强制转换的情况下仍然失败），它会起作用：
String result = new JsonBuilder((Map)(new MyDomainClass().properties))