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Drools的實現並不難,關鍵是瞭解他的語法即可
入門案例
- 創建一個簡單的SpringBoot項目
- 選擇依賴的時候,添加一個web依賴即可
- 在新項目的pom.xml中添加drools的相關依賴
<properties>
<java.version>1.8</java.version>
<drools.version>7.14.0.Final</drools.version>
</properties>
<dependencies>
<!-- drools依賴 -->
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-core</artifactId>
<version>${drools.version}</version>
</dependency>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-compiler</artifactId>
<version>${drools.version}</version>
</dependency>
<!-- 決策表 -->
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-decisiontables</artifactId>
<version>${drools.version}</version>
</dependency>
<!-- 模板 -->
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-templates</artifactId>
<version>${drools.version}</version>
</dependency>
<dependency>
<groupId>org.kie</groupId>
<artifactId>kie-api</artifactId>
<version>${drools.version}</version>
</dependency>
</dependencies>
- 創建Kie相關 Bean 使其被spring管理
import org.kie.api.KieBase;
import org.kie.api.KieServices;
import org.kie.api.builder.KieBuilder;
import org.kie.api.builder.KieFileSystem;
import org.kie.api.builder.KieModule;
import org.kie.api.builder.KieRepository;
import org.kie.api.builder.ReleaseId;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;
import org.kie.internal.io.ResourceFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.io.Resource;
import java.io.IOException;
/**
* @author tang.sl
* @date 2021-01-05 09:37
*/
@Configuration
public class KiaSessionConfig {
private static final String RULES_PATH = "rules/";
@Bean
public KieFileSystem kieFileSystem() throws IOException {
KieFileSystem kieFileSystem = getKieServices().newKieFileSystem();
for (Resource file : getRuleFiles()) {
kieFileSystem.write(ResourceFactory.newClassPathResource(RULES_PATH + file.getFilename(), "UTF-8"));
}
return kieFileSystem;
}
private Resource[] getRuleFiles() throws IOException {
ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
final Resource[] resources = resourcePatternResolver.getResources("classpath*:" + RULES_PATH + "**/*.*");
return resources;
}
@Bean
public KieContainer kieContainer() throws IOException {
final KieRepository kieRepository = getKieServices().getRepository();
kieRepository.addKieModule(new KieModule() {
public ReleaseId getReleaseId() {
return kieRepository.getDefaultReleaseId();
}
});
KieBuilder kieBuilder = getKieServices().newKieBuilder(kieFileSystem());
kieBuilder.buildAll();
return getKieServices().newKieContainer(kieRepository.getDefaultReleaseId());
}
private KieServices getKieServices() {
return KieServices.Factory.get();
}
@Bean
public KieBase kieBase() throws IOException {
return kieContainer().getKieBase();
}
@Bean
public KieSession kieSession() throws IOException {
return kieContainer().newKieSession();
}
}
到目前爲止,我們的基本準備工作就已經完成了,我們可以創建實際的案例來使用Drools了。
- 根據前面的需求定義一個實體類
@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class User {
private String name;
private String age;
private String address;
private String phone;
private String sex;
}
- 創建drl規則文件 根據前幾篇文章描述的內容,我們來設計一個規則文件。文件放在resources目錄下面,在該目錄下面創建一個rules統一存放後面所有的rule文件
package com.echo.drools.dto
import com.echo.drools.dto.User
dialect "java"
rule "address eq beijing"
when
$user: User(address == "北京")
then
System.out.println($user.getName() + "是個北漂");
end
rule "address eq shanghai"
when
$user: User(address == "上海")
then
System.out.println($user.getName() + "是個上漂");
end
- 然後我們就可以來測試使用這個規則
import com.echo.drools.dto.User;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;
import org.kie.api.runtime.KieSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class DroolsApplicationTests {
@Autowired
private KieSession session;
@Test
void contextLoads() {
User user = new User();
user.setAddress("北京");
user.setAge("20");
user.setName("echo");
user.setPhone("136123456");
user.setSex("1");
// 插入用戶
session.insert(user);
// 執行規則
session.fireAllRules();
}
/**
* 記得執行完成之後釋放資源
*/
@AfterEach
public void runDispose() {
session.dispose();
}
}
- 多次測試 結果和我們的符合我們原有的預期,比如上面的實例,最終會在控制檯輸出“echo是北漂”。
注意:我們這裏僅僅寫了兩個規則,並且也沒有寫對應的業務代碼,這個後面再講,僅僅只是一個入門展示案例。不要多糾結爲什麼沒有業務代碼