Drools6.4動態加載規則之（一）模板的簡單應用

1.template

drools6開始提供模板的概念；

模板能爲我們提供簡單的規則替換；做到簡單的規則動態加載；

本例子的demo基於最新穩定版drools6.4

2.項目結構

3.pom依賴

<!--drools-->
<dependency>
    <groupId>org.drools</groupId>
    <artifactId>drools-core</artifactId>
    <version>6.4.0.Final</version>
</dependency>
<dependency>
    <groupId>org.drools</groupId>
    <artifactId>drools-decisiontables</artifactId>
    <version>6.4.0.Final</version>
</dependency>

4.代碼

Message.java

package com.caicongyang.drools.templates;

import java.io.Serializable;

/**
 * @author caicongyang1
 * @version id: Message, v 0.1 16/9/29 下午3:06 caicongyang1 Exp $$
 */
public class Message implements Serializable {

    private static final long serialVersionUID = -3168739008574463191L;

    public static final int HELLO = 0;
    public static final int GOODBYE = 1;

    private String message;

    private int status;

    public String getMessage() {
        return this.message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public int getStatus() {
        return this.status;
    }

    public void setStatus(int status) {
        this.status = status;
    }

}

MyDataProvider.java

package com.caicongyang.drools.templates;

import java.util.Iterator;
import java.util.List;

import org.drools.template.DataProvider;

/**
 * @author caicongyang1
 * @version id: Message, v 0.1 16/9/29 下午3:06 caicongyang1 Exp $$
 */
public class MyDataProvider implements DataProvider {

    private Iterator<String[]> iterator;

    public MyDataProvider(List<String[]> rows) {
        this.iterator = rows.iterator();
    }

    public boolean hasNext() {
        return iterator.hasNext();
    }

    public String[] next() {
        return iterator.next();
    }
}

DataProviderCompilerTest.java

package com.caicongyang.drools.templates;

import java.util.ArrayList;

import org.drools.template.DataProviderCompiler;
import org.kie.api.KieServices;
import org.kie.api.builder.KieBuilder;
import org.kie.api.builder.KieFileSystem;
import org.kie.api.builder.Message.Level;
import org.kie.api.builder.model.KieBaseModel;
import org.kie.api.builder.model.KieModuleModel;
import org.kie.api.io.KieResources;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;

/**
 *
 * Drools模板實例應用
 *
 * @author caicongyang1
 * @version id: Message, v 0.1 16/9/29 下午3:06 caicongyang1 Exp $$
 */
public class DataProviderCompilerTest {

    public static void main(String[] args) {
        ArrayList<String[]> rows = new ArrayList<String[]>();
        rows.add(new String[] { "1", "status == 0" });

        MyDataProvider tdp = new MyDataProvider(rows);
        DataProviderCompiler converter = new DataProviderCompiler();
        String drl = converter.compile(tdp, "/rules/rule_template_1.drl");

        System.out.println(drl);

        KieServices kieServices = KieServices.Factory.get();
        KieResources resources = kieServices.getResources();
        KieModuleModel kieModuleModel = kieServices.newKieModuleModel();//1

        KieBaseModel baseModel = kieModuleModel.newKieBaseModel("FileSystemKBase").addPackage("rules");//2
        baseModel.newKieSessionModel("FileSystemKSession");//3
        KieFileSystem fileSystem = kieServices.newKieFileSystem();

        String xml = kieModuleModel.toXML();
        System.out.println(xml);//4
        fileSystem.writeKModuleXML(xml);//5

        String path = DataProviderCompilerTest.class.getClass().getResource("/").getPath();
        fileSystem.write("src/main/resources/rules/rule1.drl", drl);

        KieBuilder kb = kieServices.newKieBuilder(fileSystem);
        kb.buildAll();//7
        if (kb.getResults().hasMessages(Level.ERROR)) {
            throw new RuntimeException("Build Errors:\n" + kb.getResults().toString());
        }
        KieContainer kContainer = kieServices.newKieContainer(kieServices.getRepository().getDefaultReleaseId());

        KieSession kSession = kContainer.newKieSession("FileSystemKSession");

        Message message = new Message();
        message.setMessage("Hello World");
        message.setStatus(Message.HELLO);

        kSession.insert(message);
        kSession.fireAllRules();
        kSession.dispose();

    }

}

rule_template_1.dl

template header
RULE_ID
RULE_KEY1

package com.caicongyang.drools.templates;

import com.caicongyang.drools.templates.Message;

template "RULE"
rule "RULE_@{RULE_ID}"
    when
        m: Message(@{RULE_KEY1})
    then
        System.out.println(m.getMessage());
end
end template

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