Drools (4): drools basic syntax (2)

The rule syntax of the result part

stay Drools among , stay RHS Inside , Provides some information on the current Working Memory Macro macro function or object to realize fast operation , such as insert/insertLogical、 update and retract You can achieve the current Working Memory Medium Fact Object into ⾏ newly added 、 Delete or modify

1 insert

function insert The role of Java Call in class StatefulKnowledgeSession Object's insert⽅ The work of law ⽤ identical , It's all used to ⼀ individual Fact Object interpolation ⼊ To the present Working Memory among

Attention should be paid to ：⼀ Dan tone ⽤ insert Macro functions , that Drools It will re match with all the rules ⼀ Time , For no settings no-loop The attribute is true The rules of , If the conditions are satisfied ⾜, Whether or not it has been carried out before ⾏ I will cling to it again after I have passed ⾏⼀ Time , This feature does not exist only in insert On macro function , after ⾯ To introduce the update、retract Macro functions also have this feature , So in some cases, due to improper consideration ⽤ insert、update or retract Prone to life and death cycle

Example ：

//Drools Built in ⽅ Law insert
rule "rule5"
    when
        eval(true);
        // Default to ⽴
    then
        Customer cus=new Customer();
        cus.setName(" Zhang San ");
        insert(cus);
        System.out.println(" test Drools Built in ⽅ Law insert  Trigger ...");
end

rule "rule6"
    when
        $customer:Customer(name ==" Zhang San ");
    then
        System.out.println(" test Drools Built in ⽅ Law insert  touch   Hair ..."+$customer.getName());
end

test ：

    @Test
    public void test4() {
        KieServices kieServices = KieServices.Factory.get();
        KieContainer kieContainer = kieServices.getKieClasspathContainer();
        // Conversation object ,⽤ Interact with the rule engine 
        KieSession kieSession = kieContainer.newKieSession();
        // Activate rule engine , If the match is successful, execute ⾏ The rules 
        kieSession.fireAllRules();
        // Close session 
        kieSession.dispose();
    }

The results are as follows ：

insertLogical

insertLogical The functions and insert similar , Its work ⽤ Will be ⼀ individual Fact Object interpolation ⼊ To the present Working Memroy among

2 update

update Function meaning and its name ⼀ sample ,⽤ To realize the current Working Memory In the middle of Fact Into the ⾏ to update , Used to tell the current Working Memory The Fact The object has changed .

Example ：

rule "rule7"
//no-loop true
when
    $customer:Customer(name ==" Li Si ");
    then
    $customer.setName(" Zhang San ");
    update($customer);
    System.out.println(" test Drools Built in ⽅ Law update  Trigger ...");
end

rule "rule8"
    when
    $customer:Customer(name ==" Zhang San ");
    then
        System.out.println(" test Drools Built in ⽅ Law update  touch   Hair ..."+$customer.getName());
end

test ：

    @Test
    public void test5() {
        KieServices kieServices = KieServices.Factory.get();
        KieContainer kieContainer = kieServices.getKieClasspathContainer();
        // Conversation object ,⽤ Interact with the rule engine 
        KieSession kieSession = kieContainer.newKieSession();
        Customer customer = new Customer();
        customer.setName(" Li Si ");
        kieSession.insert(customer);
        // Activate rule engine , If the match is successful, execute ⾏ The rules 
        kieSession.fireAllRules();
        // Close session 
        kieSession.dispose();
    }

The results are as follows ：

3 retract

retract⽤ to Working Memory One of them Fact Objects from Working Memory Delete

//Drools Built in ⽅ Law retract
rule "rule9"
    when
        $customer:Customer(name ==" Li Si ");
    then
    retract($customer);
    System.out.println(" test Drools Built in ⽅ Law retract  Trigger ...");
end

rule "rule10"
    when
        $customer:Customer();
    then
        System.out.println(" test Drools Built in ⽅ Law retract  touch   Hair ..."+$customer.getName());
end

test ：

    @Test
    public void test6() {
        KieServices kieServices = KieServices.Factory.get();
        KieContainer kieContainer = kieServices.getKieClasspathContainer();
        // Conversation object ,⽤ Interact with the rule engine 
        KieSession kieSession = kieContainer.newKieSession();
        Customer customer = new Customer();
        customer.setName(" Li Si ");
        kieSession.insert(customer);
        // Activate rule engine , If the match is successful, execute ⾏ The rules 
        kieSession.fireAllRules();
        // Implement execution only through rule filters ⾏ Specify the rules 
        // kieSession.fireAllRules(new RuleNameEqualsAgendaFilter("rule5"));
        //  Close session 
        kieSession.dispose();
    }

  The results are as follows ：

rule9 The data of Li Si has been deleted , therefore rule10 No implementation .

If you will retract Comment out and then execute , give the result as follows ： 

Rule not implemented retract, therefore rule10 The rules take effect .