近日在公司领到一个小需求,需要对之前已有的试用用户申请规则进行拓展。我们的场景大概如下所示:
if (是否海外用户) {
return false;
}
if (刷单用户) {
return false;
}
if (未付费用户 && 不再服务时段) {
return false
}
if (转介绍用户 || 付费用户 || 内推用户) {
return true;
}
按照上述的条件我们可以得出的结论是:
后面进过权衡过后,我还是决定将这个部分进行重构一下。
针对这个需求,我首先梳理了一下咱们规则执行器大概的设计, 然后我设计了一个 V1 版本和大家一起分享一下,如果大家也有这样的 case 可以给我分享留言,下面部分主要是设计和实现的流程和 code.
// 业务数据
@Data
public class RuleDto {
private String address;
private int age;
}
// 规则抽象
public interface BaseRule {
boolean execute(RuleDto dto);
}
// 规则模板
public abstract class AbstractRule implements BaseRule {
protected <T> T convert(RuleDto dto) {
return (T) dto;
}
@Override
public boolean execute(RuleDto dto) {
return executeRule(convert(dto));
}
protected <T> boolean executeRule(T t) {
return true;
}
}
// 具体规则- 例子1
public class AddressRule extends AbstractRule {
@Override
public boolean execute(RuleDto dto) {
System.out.println("AddressRule invoke!");
if (dto.getAddress().startsWith(MATCH_ADDRESS_START)) {
return true;
}
return false;
}
}
// 具体规则- 例子2
public class NationalityRule extends AbstractRule {
@Override
protected <T> T convert(RuleDto dto) {
NationalityRuleDto nationalityRuleDto = new NationalityRuleDto();
if (dto.getAddress().startsWith(MATCH_ADDRESS_START)) {
nationalityRuleDto.setNationality(MATCH_NATIONALITY_START);
}
return (T) nationalityRuleDto;
}
@Override
protected <T> boolean executeRule(T t) {
System.out.println("NationalityRule invoke!");
NationalityRuleDto nationalityRuleDto = (NationalityRuleDto) t;
if (nationalityRuleDto.getNationality().startsWith(MATCH_NATIONALITY_START)) {
return true;
}
return false;
}
}
// 常量定义
public class RuleConstant {
public static final String MATCH_ADDRESS_START= "北京";
public static final String MATCH_NATIONALITY_START= "中国";
}
public class RuleService {
private Map<Integer, List<BaseRule>> hashMap = new HashMap<>();
private static final int AND = 1;
private static final int OR = 0;
public static RuleService create() {
return new RuleService();
}
public RuleService and(List<BaseRule> ruleList) {
hashMap.put(AND, ruleList);
return this;
}
public RuleService or(List<BaseRule> ruleList) {
hashMap.put(OR, ruleList);
return this;
}
public boolean execute(RuleDto dto) {
for (Map.Entry<Integer, List<BaseRule>> item : hashMap.entrySet()) {
List<BaseRule> ruleList = item.getValue();
switch (item.getKey()) {
case AND:
// 如果是 and 关系,同步执行
System.out.println("execute key = " + 1);
if (!and(dto, ruleList)) {
return false;
}
break;
case OR:
// 如果是 or 关系,并行执行
System.out.println("execute key = " + 0);
if (!or(dto, ruleList)) {
return false;
}
break;
default:
break;
}
}
return true;
}
private boolean and(RuleDto dto, List<BaseRule> ruleList) {
for (BaseRule rule : ruleList) {
boolean execute = rule.execute(dto);
if (!execute) {
// and 关系匹配失败一次,返回 false
return false;
}
}
// and 关系全部匹配成功,返回 true
return true;
}
private boolean or(RuleDto dto, List<BaseRule> ruleList) {
for (BaseRule rule : ruleList) {
boolean execute = rule.execute(dto);
if (execute) {
// or 关系匹配到一个就返回 true
return true;
}
}
// or 关系一个都匹配不到就返回 false
return false;
}
}
public class RuleServiceTest {
@org.junit.Test
public void execute() {
//规则执行器
//优点:比较简单,每个规则可以独立,将规则,数据,执行器拆分出来,调用方比较规整
//缺点:数据依赖公共传输对象 dto
//1. 定义规则 init rule
AgeRule ageRule = new AgeRule();
NameRule nameRule = new NameRule();
NationalityRule nationalityRule = new NationalityRule();
AddressRule addressRule = new AddressRule();
SubjectRule subjectRule = new SubjectRule();
//2. 构造需要的数据 create dto
RuleDto dto = new RuleDto();
dto.setAge(5);
dto.setName("张三");
dto.setAddress("北京");
dto.setSubject("数学");;
//3. 通过以链式调用构建和执行 rule execute
boolean ruleResult = RuleService
.create()
.and(Arrays.asList(nationalityRule, nameRule, addressRule))
.or(Arrays.asList(ageRule, subjectRule))
.execute(dto);
System.out.println("this student rule execute result :" + ruleResult);
}
}
规则执行器的优点和缺点
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