Java 可以将Drools配置为将规则应用于“插入的对象”字段中包含的对象吗？

我有一套复杂的规则要在Drools中实现，我正在努力避免重复的规则。例如，我有一个ForeignPerson类，它被另外两个类使用

public class ForeignPerson {
  private String name;
  private String country;
}

public class Owner {
  private Individual individual;
  private ForeignPerson foreignPerson;
}

public class Beneficiary {
  private Individual individual;
  private ForeignPerson foreignPerson;
}

在每一个外国人的例子中，国家字段必须是“USA”。我希望能够执行

kieSession.insert（所有者）

如果ForeignPerson字段不为空，请检查ForeignPerson规则以及所有者规则

ForeignPerson.drl规则文件如下：

rule "R001: Country must == USA"
  when 
    ForeignPerson(country != "USA")
  then 
    System.out.println("Country must be USA");
end

rule "R001: Foreign Person must exist"
  when 
    Owner(foreignPerson == null)
  then 
    System.out.println("foreignPerson must not be null");
end

Owner.drl规则文件，如：

rule "R001: Country must == USA"
  when 
    ForeignPerson(country != "USA")
  then 
    System.out.println("Country must be USA");
end

rule "R001: Foreign Person must exist"
  when 
    Owner(foreignPerson == null)
  then 
    System.out.println("foreignPerson must not be null");
end

我不想像下面那样编写Owner.drl文件，因为它会导致大量重复的规则

rule "R001: Foreign Person must exist"
  when 
    Owner(foreignPerson == null)
  then 
    System.out.println("foreignPerson must not be null");
end

rule "R002: Foreign Person country must be USA"
  when 
    Owner(foreignPerson != null, foreignPerson.getCountry() != "USA")
  then 
    System.out.println("foreignPerson must have country USA");
end

---

这是可能的还是唯一一种单独注入对象的方法？

这条规则确定外国人来自美国

rule "from the US"
when 
  $foreignPerson: ForeignPerson( country == "USA" )
then
end

您可以使用此选项检查所有者事实：

rule "owner from the US"
  extends "from the US"
when
  Owner( foreignPerson == $foreignPerson )
then
  // ... owner is from the US
end

---

受益人也是如此。

简短的回答是“否”。每个要直接检查的对象必须单独插入。extends关键字可用于验证对象是否具有正确的父对象（请参见此问题）