责任链模式
简介
定义: 为请求创建一个接收者对象的链，沿着链传递请求直到有对象处理它。
使用场景:
请假审批流程
异常处理链
Servlet过滤器链
Spring Security过滤器
实现要点:
每个处理器持有下一个处理器引用
链式调用
可以动态组合
UML
代码示例
抽象审批处理器
public abstract class ApprovalHandler {
/**
* 下一个处理器
*/
protected ApprovalHandler nextHandler;
/**
* 设置下一个处理器
*/
public void setNext(ApprovalHandler handler) {
this.nextHandler = handler;
}
/**
* 处理请求
*/
public final ApprovalResult handle(LeaveRequest request) {
// 当前处理器处理请求
ApprovalResult result = doHandle(request);
// 如果当前处理器无法处理或拒绝，则传递给下一个处理器
if (nextHandler != null && (!result.isApproved() || !canHandle(request))) {
result = nextHandler.handle(request);
}
return result;
}
/**
* 具体的处理逻辑，由子类实现
*/
protected abstract ApprovalResult doHandle(LeaveRequest request);
/**
* 判断当前处理器是否可以处理该请求
*/
protected abstract boolean canHandle(LeaveRequest request);
/**
* 获取处理器名称
*/
protected abstract String getHandlerName();
}各个处理器
/**
* @author dcx
* @description 董事会处理器 - 处理超长请假申请
* @create 2025-01-27
*/
public class BoardHandler extends ApprovalHandler {
@Override
protected ApprovalResult doHandle(LeaveRequest request) {
if (request.getLeaveDays() <= 90) {
return ApprovalResult.approved(getHandlerName(),
String.format("董事会批准%s的%d天请假申请", request.getEmployeeName(), request.getLeaveDays()));
} else {
return ApprovalResult.rejected(getHandlerName(),
String.format("请假天数超过90天，建议办理停薪留职"));
}
}
@Override
protected boolean canHandle(LeaveRequest request) {
return true; // 董事会是最高级别，可以处理所有请求
}
@Override
protected String getHandlerName() {
return "董事会";
}
}
/**
* @author dcx
* @description 部门经理处理器 - 可以审批7天以内的请假
* @create 2025-01-27
*/
public class DepartmentManagerHandler extends ApprovalHandler {
@Override
protected ApprovalResult doHandle(LeaveRequest request) {
if (request.getLeaveDays() <= 7) {
return ApprovalResult.approved(getHandlerName(),
String.format("部门经理批准%s的%d天请假申请", request.getEmployeeName(), request.getLeaveDays()));
} else {
return ApprovalResult.rejected(getHandlerName(),
String.format("请假天数超过7天，需要总经理审批"));
}
}
@Override
protected boolean canHandle(LeaveRequest request) {
return request.getLeaveDays() <= 7;
}
@Override
protected String getHandlerName() {
return "部门经理";
}
}
/**
* @author dcx
* @description 总经理处理器 - 可以审批任意天数的请假
* @create 2025-01-27
*/
public class GeneralManagerHandler extends ApprovalHandler {
@Override
protected ApprovalResult doHandle(LeaveRequest request) {
if (request.getLeaveDays() <= 30) {
return ApprovalResult.approved(getHandlerName(),
String.format("总经理批准%s的%d天请假申请", request.getEmployeeName(), request.getLeaveDays()));
} else {
return ApprovalResult.rejected(getHandlerName(),
String.format("请假天数超过30天，需要董事会决议"));
}
}
@Override
protected boolean canHandle(LeaveRequest request) {
return request.getLeaveDays() <= 30;
}
@Override
protected String getHandlerName() {
return "总经理";
}
}
/**
* @author dcx
* @description 团队负责人处理器 - 可以审批3天以内的请假
* @create 2025-01-27
*/
public class TeamLeaderHandler extends ApprovalHandler {
@Override
protected ApprovalResult doHandle(LeaveRequest request) {
if (request.getLeaveDays() <= 3) {
return ApprovalResult.approved(getHandlerName(),
String.format("团队负责人批准%s的%d天请假申请", request.getEmployeeName(), request.getLeaveDays()));
} else {
return ApprovalResult.rejected(getHandlerName(),
String.format("请假天数超过3天，需要上级审批"));
}
}
@Override
protected boolean canHandle(LeaveRequest request) {
return request.getLeaveDays() <= 3;
}
@Override
protected String getHandlerName() {
return "团队负责人";
}
}请求和响应体
@Data
public class LeaveRequest {
/**
* 员工姓名
*/
private String employeeName;
/**
* 请假天数
*/
private int leaveDays;
/**
* 请假原因
*/
private String reason;
public LeaveRequest(String employeeName, int leaveDays, String reason) {
this.employeeName = employeeName;
this.leaveDays = leaveDays;
this.reason = reason;
}
@Override
public String toString() {
return String.format("员工: %s, 请假天数: %d, 请假原因: %s",
employeeName, leaveDays, reason);
}
}
@Data
public class ApprovalResult {
/**
* 是否通过
*/
private boolean approved;
/**
* 审批人
*/
private String approver;
/**
* 审批意见
*/
private String comment;
public ApprovalResult(boolean approved, String approver, String comment) {
this.approved = approved;
this.approver = approver;
this.comment = comment;
}
public static ApprovalResult approved(String approver, String comment) {
return new ApprovalResult(true, approver, comment);
}
public static ApprovalResult rejected(String approver, String comment) {
return new ApprovalResult(false, approver, comment);
}
@Override
public String toString() {
return String.format("审批结果: %s, 审批人: %s, 意见: %s",
approved ? "通过" : "拒绝", approver, comment);
}
}
使用方式
public class Test {
public static void main(String[] args) {
// 创建责任链
ApprovalHandler teamLeader = new TeamLeaderHandler();
ApprovalHandler departmentManager = new DepartmentManagerHandler();
ApprovalHandler generalManager = new GeneralManagerHandler();
ApprovalHandler board = new BoardHandler();
// 设置责任链的顺序：团队负责人 -> 部门经理 -> 总经理 -> 董事会
teamLeader.setNext(departmentManager);
departmentManager.setNext(generalManager);
generalManager.setNext(board);
// 创建测试用例
LeaveRequest[] testCases = {
new LeaveRequest("张三", 2, "感冒发烧"),
new LeaveRequest("李四", 5, "家里有事"),
new LeaveRequest("王五", 10, "旅游度假"),
new LeaveRequest("赵六", 25, "探亲访友"),
new LeaveRequest("钱七", 60, "长期病假"),
new LeaveRequest("孙八", 120, "创业准备")
};
System.out.println("=== 责任链模式 - 请假审批系统 ===\n");
// 测试各种请假申请
for (LeaveRequest request : testCases) {
System.out.println("提交申请: " + request);
ApprovalResult result = teamLeader.handle(request);
System.out.println("审批结果: " + result);
System.out.println("----------------------------------------");
}
System.out.println("\n=== 责任链模式说明 ===");
System.out.println("1. 团队负责人: 可审批3天以内");
System.out.println("2. 部门经理: 可审批7天以内");
System.out.println("3. 总经理: 可审批30天以内");
System.out.println("4. 董事会: 可审批90天以内");
System.out.println("5. 超过90天: 建议停薪留职");
}
}
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