drools决策表的简单使用

一、背景

在之前的文章中，我们的业务规则都是写在了drl文件中，这对开发人员来说是没有什么问题，如果是业务人员则不怎么友好，这篇文章我们简单学习一下drools中决策表的使用，规则是写在excel文件中。

二、一个简单的决策表

01-决策表.jpg

在上面这个图中ResultSet和ResultTable是必须的，_{而且同一个包中，我们最好只上传一个决策表。}

1、在同一个决策表中处理多个Sheet页

02-同一个决策表中处理多个Sheet页.jpg

2、RuleSet下方可以有哪些属性

Label	Value	Usage
RuleSet	The package name for the generated DRL file. Optional, the default is rule_table.	Must be the first entry.
Sequential	true or false. If true, then salience is used to ensure that rules fire from the top down.	Optional, at most once. If omitted, no firing order is imposed.
SequentialMaxPriority	Integer numeric value	Optional, at most once. In sequential mode, this option is used to set the start value of the salience. If omitted, the default value is 65535.
SequentialMinPriority	Integer numeric value	Optional, at most once. In sequential mode, this option is used to check if this minimum salience value is not violated. If omitted, the default value is 0.
EscapeQuotes	true or false. If true, then quotation marks are escaped so that they appear literally in the DRL.	Optional, at most once. If omitted, quotation marks are escaped.
IgnoreNumericFormat	true or false. If true, then the format for numeric values is ignored, for example, percent and currency.	Optional, at most once. If omitted, DRL takes formatted values.
Import	A comma-separated list of Java classes to import from another package.	Optional, may be used repeatedly.
Variables	Declarations of DRL globals (a type followed by a variable name). Multiple global definitions must be separated by commas.	Optional, may be used repeatedly.
Functions	One or more function definitions, according to DRL syntax.	Optional, may be used repeatedly.
Queries	One or more query definitions, according to DRL syntax.	Optional, may be used repeatedly.
Declare	One or more declarative types, according to DRL syntax.	Optional, may be used repeatedly.
Unit	The rule units that the rules generated from this decision table belong to.	Optional, at most once. If omitted, the rules do not belong to any unit.
Dialect	java or mvel. The dialect used in the actions of the decision table.	Optional, at most once. If omitted, java is imposed.

ResultSet：区域只可有一个。

3、RuleTable下方可以有哪些属性

Label	Or custom label that begins with	Value	Usage
NAME	N	Provides the name for the rule generated from that row. The default is constructed from the text following the RuleTable tag and the row number.	At most one column.
DESCRIPTION	I	Results in a comment within the generated rule.	At most one column.
CONDITION	C	Code snippet and interpolated values for constructing a constraint within a pattern in a condition.	At least one per rule table.
ACTION	A	Code snippet and interpolated values for constructing an action for the consequence of the rule.	At least one per rule table.
METADATA	@	Code snippet and interpolated values for constructing a metadata entry for the rule.	Optional, any number of columns.

具体的使用可以见上方的图

4、规则属性的编写

在ResultSet和ResultTable这个地方都可以编写规则属性。ResultSet地方的规则属性将影响同一个包下所有的规则，而ResultTable这个地方的规则属性，只影响这个规则。ResultTable的优先级更高。

支持的规则属性有：PRIORITY、DATE-EFFECTIVE、DATE-EXPIRES、NO-LOOP、AGENDA-GROUP、ACTIVATION-GROUP、DURATION、TIMER、CALENDAR、AUTO-FOCUS、LOCK-ON-ACTIVE、RULEFLOW-GROUP。

具体的用法：见上图中ACTIVATION-GROUP的使用。

三、需求

我们需要根据学生的成绩分数，给出相应的结果。规则如下：

特殊处理的规则：
规则一：只要名字是张三的，直接判定为 优
规则二：只要名字是李四的，如果分数在0,60之间，直接认为是一般

普通规则：
规则三：分数在0,60之间认为是不及格
规则四：分数在60,70之间认为是一般
规则五：分数在70,90之间认为是良好
规则六：分数在90,100之间认为是优

从上方的规则中，我们可以看到姓名为张三和李四的学生特殊处理了。

四、实现

1、项目实现结构图

03-项目结果图.jpg

2、引入jar包

    
        
            org.drools
            drools-bom
            pom
            7.69.0.Final
            import
        
    



    
        org.drools
        drools-compiler
    
    
        org.drools
        drools-mvel
    
    
    
        org.drools
        drools-decisiontables
    
    
        ch.qos.logback
        logback-classic
        1.2.11
    
    
        org.projectlombok
        lombok
        1.18.22
    

3、编写kmodule.xml文件

4、编写学生实体类

@Getter
@Setter
@ToString
public class Student {

    private String name;
    // 分数只能在 0-100 之间
    private Integer score;

    public Student(String name, Integer score) {
        this.name = name;
        if (null == score || score < 0 || score > 100) {
            throw new RuntimeException("分数只能在0-100之间");
        }
        this.score = score;
    }
}

5、编写决策表

01-决策表.jpg

6、将决策表转换成drl文件

这步主要是为了查看我们的决策表编写的是否正确，看看最终生成的drl文件是什么样的。

1、决策表转换成drl文件代码

/**
* 决策表转换成 drl 文件
*/
public static void decisionTable2Drl() throws IOException {
    Resource resource = ResourceFactory.newClassPathResource("rules/decision/tables/student-score.xlsx", "UTF-8");
    InputStream inputStream = resource.getInputStream();
    SpreadsheetCompiler compiler = new SpreadsheetCompiler();
    String drl = compiler.compile(inputStream, InputType.XLS);
    log.info("决策表转换的drl内容为:\r{}", drl);

    // 验证一下 drl 文件是否有问题
    KieHelper kieHelper = new KieHelper();
    Results results = kieHelper.addContent(drl, ResourceType.DRL).verify();
    List messages = results.getMessages(Message.Level.ERROR);
    if (null != messages && !messages.isEmpty()) {
        for (Message message : messages) {
            log.error(message.getText());
        }
    }
}

2、转换成具体的drl文件为

package rules.decision.tables;
//generated from Decision Table
import java.lang.StringBuilder;
import com.huan.drools.Student;
global java.lang.StringBuilder resultsInfo;



// rule values at B15, header at B10
rule "student-score-name-1"
/* 1、姓名为张三的特殊处理
2、自定义规则的名字 */
    salience 65535
    activation-group "score"
    when
        $stu: Student(name == "张三")
    then
        resultsInfo.append("张三特殊处理：");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
        resultsInfo.append("优");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
end

// rule values at B16, header at B10
rule "student-score_16"
    salience 65534
    activation-group "score"
    when
        $stu: Student(name == "李四", score > 0 && score < 60)
    then
        resultsInfo.append("李四部分特殊处理：");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
        resultsInfo.append("一般");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
end

// rule values at B17, header at B10
rule "student-score_17"
    salience 65533
    activation-group "score"
    when
        $stu: Student(score > 0 && score < 60)
    then
        resultsInfo.append("不及格");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
end

// rule values at B18, header at B10
rule "student-score_18"
    salience 65532
    activation-group "score"
    when
        $stu: Student(score > 60 && score < 70)
    then
        resultsInfo.append("一般");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
end

// rule values at B19, header at B10
rule "student-score_19"
    salience 65531
    activation-group "score"
    when
        $stu: Student(score > 70 && score < 90)
    then
        resultsInfo.append("良好");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
end

// rule values at B20, header at B10
rule "student-score_20"
    salience 65530
    activation-group "score"
    when
        $stu: Student(score > 90 && score < 100)
    then
        resultsInfo.append("优");
System.out.println("规则:" + drools.getRule().getName() + " 执行了.");
end

从上方可以看出第一个规则的规则名称是不一样的，而且存在一些描述信息，这个是在决策表中特殊处理了。

7、测试

1、编写测试代码

package com.huan.drools;

import lombok.extern.slf4j.Slf4j;
import org.drools.decisiontable.InputType;
import org.drools.decisiontable.SpreadsheetCompiler;
import org.kie.api.KieServices;
import org.kie.api.builder.Message;
import org.kie.api.builder.Results;
import org.kie.api.io.Resource;
import org.kie.api.io.ResourceType;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;
import org.kie.internal.io.ResourceFactory;
import org.kie.internal.utils.KieHelper;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

/**
 * drools 决策表的使用
 */
@Slf4j
public class DroolsDecisionTableApplication {
    public static void main(String[] args) throws IOException {
        decisionTable2Drl();
        KieServices kieServices = KieServices.get();
        KieContainer kieContainer = kieServices.newKieClasspathContainer();
        // 张三虽然只得20分，但是根据规则判断，结果应该是  优
        invokedDecisionTable(kieContainer, new Student("张三", 20));
        // 李四虽然只得20分，但是根据规则判断，结果应该是  一般
        invokedDecisionTable(kieContainer, new Student("李四", 20));
        // 李四得75分，但是根据规则判断，结果应该是  良好
        invokedDecisionTable(kieContainer, new Student("李四", 75));
        // 王五得59分，但是根据规则判断，结果应该是  不及格
        invokedDecisionTable(kieContainer, new Student("王五", 59));
        // 赵六得20分，但是根据规则判断，结果应该是  一般
        invokedDecisionTable(kieContainer, new Student("赵六", 65));
        // 钱七得20分，但是根据规则判断，结果应该是  良好
        invokedDecisionTable(kieContainer, new Student("钱七", 75));
        // 李八得20分，但是根据规则判断，结果应该是  优
        invokedDecisionTable(kieContainer, new Student("李八", 95));
    }

    public static void invokedDecisionTable(KieContainer kieContainer, Student student) {
        System.out.println("\r");
        KieSession kieSession = kieContainer.newKieSession("ksession");
        StringBuilder result = new StringBuilder();
        kieSession.setGlobal("resultsInfo", result);
        kieSession.insert(student);
        kieSession.fireAllRules();
        kieSession.dispose();
        System.out.println("规则执行结果：" + result);
    }

    /**
     * 决策表转换成 drl 文件
     */
    public static void decisionTable2Drl() throws IOException {
        Resource resource = ResourceFactory.newClassPathResource("rules/decision/tables/student-score.xlsx", "UTF-8");
        InputStream inputStream = resource.getInputStream();
        SpreadsheetCompiler compiler = new SpreadsheetCompiler();
        String drl = compiler.compile(inputStream, InputType.XLS);
        log.info("决策表转换的drl内容为:\r{}", drl);
        // 验证一下 drl 文件是否有问题
        KieHelper kieHelper = new KieHelper();
        Results results = kieHelper.addContent(drl, ResourceType.DRL).verify();
        List messages = results.getMessages(Message.Level.ERROR);
        if (null != messages && !messages.isEmpty()) {
            for (Message message : messages) {
                log.error(message.getText());
            }
        }
    }
}

2、测试结果

04-执行结果.jpg

从上图中可知，我们的规则都正常执行了。

五、完整代码

https://gitee.com/huan1993/spring-cloud-parent/tree/master/drools/drools-decision-table

六、参考文档

1、https://docs.drools.org/7.69.0.Final/drools-docs/html_single/index.html#decision-tables-con_decision-tables