基于 Drools 的具体业务规则示例

// 规则文件：PromotionRules.drl
package com.ecommerce.promotion// 定义事实类型（可映射Java实体类）
declare OrdertotalAmount : double    // 订单总金额discount : double       // 折扣比例（如0.8表示8折）finalPrice : double     // 最终价格
enddeclare Customertype : String           // 用户类型："VIP"或"NORMAL"
end// 规则1：VIP用户满1000元打8折
rule "VIP 1000+ discount 20%"when$customer : Customer(type == "VIP")$order : Order(totalAmount >= 1000, discount == 0)  // 未应用过折扣then$order.setDiscount(0.8);update($order);  // 更新订单，触发后续规则
end// 规则2：VIP用户满500元打9折（优先级低于规则1）
rule "VIP 500+ discount 10%"salience 5  // 优先级低于默认值（10），确保规则1先执行when$customer : Customer(type == "VIP")$order : Order(totalAmount >= 500, totalAmount < 1000, discount == 0)then$order.setDiscount(0.9);update($order);
end// 规则3：普通用户满1000元打9折
rule "Normal user 1000+ discount 10%"when$customer : Customer(type == "NORMAL")$order : Order(totalAmount >= 1000, discount == 0)then$order.setDiscount(0.9);update($order);
end// 规则4：满2000元额外减200元（所有用户适用）
rule "All users 2000+ subtract 200"when$order : Order(totalAmount >= 2000)thendouble price = $order.getTotalAmount() * $order.getDiscount();$order.setFinalPrice(price - 200);
end

// 规则文件：LoanApprovalRules.drl
package com.bank.loandeclare ApplicantcreditScore : int       // 信用分monthlyIncome : double  // 月收入debtRatio : double      // 负债率（负债/收入）
enddeclare LoanApplicationapproved : boolean      // 是否批准amount : double         // 申请额度approvedAmount : double // 批准额度
end// 规则1：优质客户批准全额贷款
rule "Approve full amount for excellent applicants"when$applicant : Applicant(creditScore >= 700, monthlyIncome >= 10000, debtRatio <= 0.3)$app : LoanApplication(approved == false)then$app.setApproved(true);$app.setApprovedAmount($app.getAmount());System.out.println("批准全额贷款：" + $app.getApprovedAmount() + "元");
end// 规则2：普通客户批准80%额度
rule "Approve 80% for good applicants"when$applicant : Applicant(creditScore >= 600, creditScore < 700, monthlyIncome >= 8000, debtRatio <= 0.4)$app : LoanApplication(approved == false)then$app.setApproved(true);$app.setApprovedAmount($app.getAmount() * 0.8);System.out.println("批准80%贷款：" + $app.getApprovedAmount() + "元");
end// 规则3：拒绝其他情况
rule "Reject other applicants"when$app : LoanApplication(approved == false)then$app.setApproved(false);System.out.println("贷款申请被拒绝");
end

// 规则文件：ConflictResolution.drl
package com.example.conflictdeclare Userlevel : int  // 用户等级：1-普通，2-会员，3-VIP
end// 规则A：VIP用户优先获得赠品A（高优先级）
rule "VIP gets Gift A"salience 20  // 优先级最高whenUser(level == 3)thenSystem.out.println("发放赠品A（VIP专属）");
end// 规则B：会员用户获得赠品B（中优先级）
rule "Member gets Gift B"salience 10  // 优先级次之whenUser(level == 2)thenSystem.out.println("发放赠品B（会员专属）");
end// 规则C：所有用户获得基础赠品（低优先级）
rule "All users get Basic Gift"salience 5  // 优先级最低whenUser()thenSystem.out.println("发放基础赠品");
end