java-rule-engine's Introduction

java-rule-engine: Rule Engine Libraries for Java

Java-rule-engine is a simple java based rule engine libraries that supports creating rule with conditions and actions, also comes with a native rule engine to execute rules.

Dependencies

Example

Define conditions

    Condition male = new SimpleCondition<>("gender", "male");
    Condition female = new SimpleCondition<>("gender", "female");

    Condition adult = new RangeCondition<Integer>("age", 18, 100);
    Condition notAdult = NotCondition.reverse(adult);

    Condition maleAdult = ConditionGroup.all(male, adult);
    Condition femaleAdult = ConditionGroup.all(female, adult);
    Condition maleNotAdult = ConditionGroup.all(male, notAdult);
    Condition adultMaleOrFemale = ConditionGroup.all(ConditionGroup.any(male, female), adult);

Define actions

    Action<Fact> print = f -> System.out.println("rule fired");
    Action<Fact> printprint = ActionChain.all(Arrays.asList(print, print));

Define rules

    Rule<Fact> printWhenMaleNotAdult = new BaseRule<>()
            .setName("print when male not adult")
            .setPriority(1)
            .setExclusive(false)
            .given(maleNotAdult)
            .then(printprint);

    Rule<Fact> printForFemaleAdult = new BaseRule<>()
            .setName("print for female adult")
            .setPriority(2)
            .setExclusive(false)
            .given(femaleAdult)
            .then(print);

Define fact and run rules

    RuleEngine ruleEngine = new NativeRuleEngineImpl();

    List<KVFactPair> facts = new ArrayList<>();
    facts.add(new KVFactPair("gender", "male"));
    facts.add(new KVFactPair("age", 20));

    Fact fact = new DefaultKVFact(new KVFactPairs(facts));
    ruleEngine.runRules(Arrays.asList(printWhenMaleNotAdult, printForFemaleAdult), fact);

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