目的
官方的Drools范例大都是基于纯Java项目或Maven项目，而基于Spring Boot项目的很少。
本文介绍如何在Spring Boot项目上加上Drools规则引擎。
POM依赖
POM文件如下：
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.galaxyyao</groupId>
<artifactId>springbootdroolstest1</artifactId>
<version>1.0.0</version>
<packaging>jar</packaging>
<name>springbootdroolstest1</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
</properties>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-core</artifactId>
<version>7.0.0.Final</version>
</dependency>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-compiler</artifactId>
<version>7.0.0.Final</version>
</dependency>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-decisiontables</artifactId>
<version>7.0.0.Final</version>
</dependency>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-templates</artifactId>
<version>7.0.0.Final</version>
</dependency>
<dependency>
<groupId>org.kie</groupId>
<artifactId>kie-api</artifactId>
<version>7.0.0.Final</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<configuration>
<executable>java</executable>
<arguments>
<argument>com.galaxyyao.springbootdroolstest1.SpringBootDroolsTest1Application</argument>
</arguments>
</configuration>
</plugin>
</plugins>
</build>
</project>
其中比较需要注意的是使用了exec-maven-plugin插件，不然无法启动
引用的Drools包的版本可以自行调整。
Resources
在src/main/resources下添加两个目录：
META-INF和rules
META-INF下添加kmodule.xml，内容如下：
<kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule"> <kbase name="rules" packages="rules"> <ksession name="ksession-rules"/> </kbase> </kmodule>
rules目录下添加一个简单的Hello World规则
package com.galaxyyao.springbootdroolstest1
import com.galaxyyao.springbootdroolstest1.domain.Message
dialect "mvel"
rule "Hello World"
dialect "mvel"
when
m : Message(status.equals(Message.HELLO), message : message )
then
System.out.println( message);
modify ( m ) { message = "Goodbye cruel world",status = Message.GOODBYE };
end
rule "Good Bye"
dialect "java"
when
Message( status == Message.GOODBYE, message : message )
then
System.out.println( message );
end
Domain层
Domain层定义一个Drools中需要使用到的Model：
package com.galaxyyao.springbootdroolstest1.domain;
public class Message {
public static final Integer HELLO = 0;
public static final Integer GOODBYE = 1;
private String message;
private Integer status;
public String getMessage() {
return this.message;
}
public void setMessage(String message) {
this.message = message;
}
public Integer getStatus() {
return this.status;
}
public void setStatus(Integer status) {
this.status = status;
}
}
Service层
Service层负责实际运行规则：
package com.galaxyyao.springbootdroolstest1.service;
import org.kie.api.KieServices;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;
import org.springframework.stereotype.Service;
import com.galaxyyao.springbootdroolstest1.domain.Message;
@Service
public class DroolsService {
public String fireRule() {
// load up the knowledge base
KieServices ks = KieServices.Factory.get();
KieContainer kContainer = ks.getKieClasspathContainer();
KieSession kSession = kContainer.newKieSession("ksession-rules");
// go !
Message message = new Message();
message.setMessage("Hello World");
message.setStatus(Message.HELLO);
kSession.insert(message);//插入
kSession.fireAllRules();//执行规则
kSession.dispose();
return message.getMessage();
}
}
