《大话设计模式》阅读笔记和总结。原书是C#编写的，本人用Java实现了一遍，包括每种设计模式的UML图实现和示例代码实现。
目录：设计模式
Github地址：DesignPattern
说明
定义：职责链模式（Chain of Responsibility），使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这个对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。
UML图：
职责链模式UML图.png
代码实现：
Handler类，定义一个处理请示的接口
abstract class Handler{
protected Handler successor;
public void setSuccessor(Handler successor) {
this.successor = successor;
}
// 处理请求的抽象方法
public abstract void HandlerRequest(int request);
}
ConcreteHandler类，具体处理者类，处理它所负责的请求，可访问它的后继者，如果可处理该请求，就处理之，否则就将该请求转发给它的后继者
/**
* ConcreteHandler1，请求数在0和10之间则有权处理，否则转到下一位
*/
class ConcreteHandler1 extends Handler{
@Override
public void HandlerRequest(int request) {
if (request >= 0 && request < 10) {
System.out.println("ConcreteHandler1处理请求"+request);
}else if(successor !=null){
successor.HandlerRequest(request);
}
}
}
/**
* ConcreteHandler2，请求数在10和20之间则有权处理，否则转到下一位
*/
class ConcreteHandler2 extends Handler{
@Override
public void HandlerRequest(int request) {
if (request >= 10 && request < 20) {
System.out.println("ConcreteHandler2处理请求"+request);
}else if(successor !=null){
successor.HandlerRequest(request);
}
}
}
/**
* ConcreteHandler3，请求数在20和30之间则有权处理，否则转到下一位
*/
class ConcreteHandler3 extends Handler{
@Override
public void HandlerRequest(int request) {
if (request >= 20 && request < 30) {
System.out.println("ConcreteHandler3处理请求"+request);
}else if(successor !=null){
successor.HandlerRequest(request);
}
}
}
客户端代码
public class ChainOfResponsibilityPattern {
public static void main(String[] args) {
Handler h1 = new ConcreteHandler1();
Handler h2 = new ConcreteHandler2();
Handler h3 = new ConcreteHandler3();
h1.setSuccessor(h2);
h2.setSuccessor(h3);
int[] requests = {2,5,14,22,18,3,27,20};
for (int i = 0; i < requests.length; i++) {
h1.HandlerRequest(requests[i]);
}
}
}
运行结果
ConcreteHandler1处理请求2
ConcreteHandler1处理请求5
ConcreteHandler2处理请求14
ConcreteHandler3处理请求22
ConcreteHandler2处理请求18
ConcreteHandler1处理请求3
ConcreteHandler3处理请求27
ConcreteHandler3处理请求20
示例
例子：在公司无论办什么事情都要走流程，一级一级审批。如果我们想请假，两天以内部门经理就可以批准，如果超过两天，五天以内总监有权限批准，五天以上就需要总经理批准了。如果我们想加薪就只能总经理审批。用程序模拟这个过程。
UML图：
职责链模式示例UML图.png
代码实现：
申请
public class Request {
// 申请类别
private String requestType;
// 申请内容
private String requestContent;
// 申请数量
private int number;
public String getRequestType() {
return requestType;
}
public void setRequestType(String requestType) {
this.requestType = requestType;
}
public String getRequestContent() {
return requestContent;
}
public void setRequestContent(String requestContent) {
this.requestContent = requestContent;
}
public int getNumber() {
return number;
}
public void setNumber(int number) {
this.number = number;
}
}
管理者
public abstract class Manager {
protected String name;
//管理者的上级
protected Manager superior;
public Manager(String name){
this.name = name;
}
public void setSuperior(Manager superior) {
this.superior = superior;
}
public abstract void RequestApplicatios(Request request);
}
总经理类
public class CommonManager extends Manager{
public CommonManager(String name) {
super(name);
}
@Override
public void RequestApplicatios(Request request) {
// 经理的权限就是可准许下两天以内的假期
if(request.getRequestType().equals("请假") && request.getNumber()<=2){
System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");
}
// 其余的申请都需转到上级
else{
if(superior!=null){
superior.RequestApplicatios(request);
}
}
}
}
总监类
public class Majordomo extends Manager{
public Majordomo(String name) {
super(name);
}
@Override
public void RequestApplicatios(Request request) {
// 经理的权限就是可准许下属一周以内的假期
if(request.getRequestType().equals("请假") && request.getNumber()<=5){
System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");
}
// 其余的申请都需转到上级
else{
if(superior!=null){
superior.RequestApplicatios(request);
}
}
}
}
总经理类，可以处理全部任何事情
public class GeneralManager extends Manager{
public GeneralManager(String name) {
super(name);
}
@Override
public void RequestApplicatios(Request request) {
if(request.getRequestType().equals("请假")){
System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");
}
else if(request.getRequestType().equals("加薪") && request.getNumber() <= 500){
System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");
}
else if(request.getRequestType().equals("加薪") && request.getNumber() > 500){
System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"再说吧");
}
}
}
客户端代码
public class Main {
public static void main(String[] args) {
CommonManager jingli = new CommonManager("经理");
Majordomo zongjian = new Majordomo("总监");
GeneralManager zongjingli = new GeneralManager("总经理");
jingli.setSuperior(zongjian);
zongjian.setSuperior(zongjingli);
Request request = new Request();
request.setRequestType("请假");
request.setRequestContent("小菜请假");
request.setNumber(1);
jingli.RequestApplicatios(request);
Request request2 = new Request();
request2.setRequestType("请假");
request2.setRequestContent("小菜请假");
request2.setNumber(4);
jingli.RequestApplicatios(request2);
Request request3 = new Request();
request3.setRequestType("加薪");
request3.setRequestContent("小菜请求加薪");
request3.setNumber(500);
jingli.RequestApplicatios(request3);
Request request4 = new Request();
request4.setRequestType("加薪");
request4.setRequestContent("小菜请求加薪");
request4.setNumber(1000);
jingli.RequestApplicatios(request4);
}
}
运行结果
经理:小菜请假 数量1被批准
总监:小菜请假 数量4被批准
总经理:小菜请求加薪 数量500被批准
总经理:小菜请求加薪 数量1000再说吧