如何在Drools中编写列表containsAny与containsAll的判断规则？

针对你的需求，我来分享一下Drools中实现这两种集合判断规则的常用方式——优先用内置操作符会更简洁易读，也可以用显式遍历的方式实现，两种都给你列出来：

这本质是判断两个集合是否有交集，Drools内置了overlaps操作符可以直接实现：

rule "Master Shares Any Group With Customer"
when
    // 从工作内存中匹配一个Master实例
    $master: Master()
    // 匹配与Master的groups有交集的Customer实例
    $customer: Customer(groups overlaps $master.groups)
then
    // 这里写规则触发后的业务逻辑，比如打印日志或更新数据
    System.out.println("Master " + $master + " has at least one common group with Customer " + $customer);
end

如果你偏好更直观的显式判断，也可以通过遍历Customer的groups元素来实现：

rule "Master Contains Any Customer Group (Explicit Check)"
when
    $master: Master($masterGroups: groups)
    $customer: Customer($customerGroups: groups)
    // 只要Customer的groups中有一个元素存在于Master的groups中，就触发规则
    $group: String() from $customerGroups
    $group memberOf $masterGroups
then
    System.out.println("Master includes group '" + $group + "' from Customer " + $customer);
end

这对应子集判断，Drools的subsetOf操作符可以直接验证Customer的groups是否是Master的groups的子集：

rule "Master Contains All Customer Groups"
when
    $master: Master()
    // 检查Customer的groups是否完全被Master的groups包含
    $customer: Customer(groups subsetOf $master.groups)
then
    System.out.println("Master " + $master + " contains every group from Customer " + $customer);
end

同样，也可以用显式的方式确保Customer的所有groups元素都在Master的groups中：

rule "Master Contains All Customer Groups (Explicit Check)"
when
    $master: Master($masterGroups: groups)
    $customer: Customer($customerGroups: groups)
    // 验证不存在任何一个Customer的group不在Master的groups中
    not( String(this not memberOf $masterGroups) from $customerGroups )
then
    System.out.println("Master includes all groups of Customer " + $customer);
end

内容的提问来源于stack exchange，提问作者Rohit Raman Das