Question

我在使用readObject（）

从文件中读取后添加Collection时遇到异常

java.lang.NullPointerException 
    at java.lang.Class.isAssignableFrom(Native Method) 
    at org.drools.base.ClassObjectType.isAssignableFrom(ClassObjectType.java:180) 
    at org.drools.reteoo.builder.PatternBuilder.attachPattern(PatternBuilder.java:95) 
    at org.drools.reteoo.builder.PatternBuilder.build(PatternBuilder.java:80) 
    at org.drools.reteoo.builder.GroupElementBuilder$AndBuilder.build(GroupElementBuilder.java:112) 
    at org.drools.reteoo.builder.GroupElementBuilder.build(GroupElementBuilder.java:70) 
    at org.drools.reteoo.builder.ReteooRuleBuilder.addSubRule(ReteooRuleBuilder.java:161) 
    at org.drools.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:134) 
    at org.drools.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:113) 
    at org.drools.reteoo.ReteooRuleBase.addRule(ReteooRuleBase.java:445) 
    at org.drools.common.AbstractRuleBase.addRule(AbstractRuleBase.java:952) 
    at org.drools.common.AbstractRuleBase.addPackages(AbstractRuleBase.java:629) 
    at org.drools.reteoo.ReteooRuleBase.addPackages(ReteooRuleBase.java:472)
    at org.drools.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:149) 
    at DroolsEmpresa.readKnowledgeBaseFromMemoryFile(DroolsEmpresa.java:304) 
    at ServidorMR.cargaInfoConocimiento(ServidorMR.java:483) 
    at Tester.main(Tester.java:127)

序列化对象的代码是

ObjectOutputStream out = new ObjectOutputStream( new FileOutputStream( fileName ) ); 
out.writeObject( kbuilder.getKnowledgePackages()); 
out.close();

反序列化的代码是

ObjectInputStream in = new ObjectInputStream( new FileInputStream( fileName) ); 
Collection<KnowledgePackage> kpkgs = (Collection<KnowledgePackage>)in.readObject(); 
in.close(); 
kbase = KnowledgeBaseFactory.newKnowledgeBase(); 
kbase.addKnowledgePackages( kpkgs );

我认为这个错误可能是由于规则造成的，但如果我在从drl文件中读取规则后运行kbase.addKnowledgePackages()，则不会有异常。

我的环境是eclipse 3.7，java 7.0.21 y drools 5.5.0。

最诚挚的问候。

更新1

使用java 7.0.05和7.0.07执行测试：错误仍然存在

Answer 1

最后问题是由于像这样的规则

...
when
    a: Concept(...)
    b: Concept(...)
    or b: Concept(...)
    and (eval(...) or eval(...))
then
...

解决方案在括号中加上第一个或。

在Drools 5.5.0中反序列化KnowledgePackage

1 个答案: