Kogito を使用してアプリケーションにルールエンジン機能を追加します。

package org.acme.kogito.model;

public class LoanApplication {

   private String id;
   private Applicant applicant;
   private int amount;
   private int deposit;
   private boolean approved = false;

   public LoanApplication() {

   }

   public LoanApplication(String id, Applicant applicant,
                      	int amount, int deposit) {
       this.id = id;
       this.applicant = applicant;
       this.amount = amount;
       this.deposit = deposit;
   }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public Applicant getApplicant() {
        return applicant;
    }

    public void setApplicant(Applicant applicant) {
        this.applicant = applicant;
    }

    public int getAmount() {
        return amount;
    }

    public void setAmount(int amount) {
        this.amount = amount;
    }

    public int getDeposit() {
        return deposit;
    }

    public void setDeposit(int deposit) {
        this.deposit = deposit;
    }

    public boolean isApproved() {
        return approved;
    }

    public void setApproved(boolean approved) {
        this.approved = approved;
    }
}

package org.acme.kogito.model;

public class Applicant {

   private String name;
   private int age;

   public Applicant() {
   }

   public Applicant(String name, int age) {
       this.name = name;
       this.age = age;
   }

   public String getName() {
       return name;
   }

   public void setName(String name) {
       this.name = name;
   }

   public int getAge() {
       return age;
   }

   public void setAge(int age) {
       this.age = age;
   }
}

package org.acme.kogito.queries;

unit LoanUnit; // no need to using globals, all variables and facts are stored in the rule unit

import org.acme.kogito.model.Applicant;
import org.acme.kogito.model.LoanApplication;

rule LargeDepositApprove when
   $l: /loanApplications[ applicant.age >= 20, deposit >= 1000, amount <= maxAmount ] // oopath style
then
   modify($l) { setApproved(true) };
end

rule LargeDepositReject when
   $l: /loanApplications[ applicant.age >= 20, deposit >= 1000, amount > maxAmount ]
then
   modify($l) { setApproved(false) };
end

// ... more loans approval/rejections business rules ...

// approved loan applications are now retrieved through a query
query FindApproved
   $l: /loanApplications[ approved ]
end

package org.acme.kogito.queries;

import org.acme.kogito.model.LoanApplication;
import org.kie.kogito.rules.DataSource;
import org.kie.kogito.rules.DataStore;
import org.kie.kogito.rules.RuleUnitData;

public class LoanUnit implements RuleUnitData {

   private int maxAmount;
   private DataStore<LoanApplication> loanApplications;

   public LoanUnit() {
   	this(DataSource.createStore(), 0);
   }

   public LoanUnit(DataStore<LoanApplication> loanApplications, int maxAmount) {
   	this.loanApplications = loanApplications;
   	this.maxAmount = maxAmount;
   }

   public DataStore<LoanApplication> getLoanApplications() { return loanApplications; }

   public void setLoanApplications(DataStore<LoanApplication> loanApplications) {
   	this.loanApplications = loanApplications;
   }

   public int getMaxAmount() { return maxAmount; }
   public void setMaxAmount(int maxAmount) { this.maxAmount = maxAmount; }
}

curl -X POST http://localhost:8080/find-approved \
    -H 'Content-Type: application/json'\
    -H 'Accept: application/json' \
    -d '{"maxAmount":5000,
          "loanApplications":[
          {"id":"ABC10001","amount":2000,"deposit":1000,
            "applicant":{"age":45,"name":"John"}},
          {"id":"ABC10002","amount":5000,"deposit":100,
            "applicant":{"age":25,"name":"Paul"}},
          {"id":"ABC10015","amount":1000,"deposit":100,
            "applicant":{"age":12,"name":"George"}}
]}'

[{"id":"ABC10001",
    "applicant":{"name":"John","age":45},
    "amount":2000,"deposit":100,"approved":true}]