七种设计原则

设计模式七大原则

1. 单一职责原则

   基本介绍

   对类来说，即一个类应该只负责一项职责，如类A负责两个不同职责：职责1，职责2，当职责1需求变更而改变A时，可能造成职责2执行错误，所以需要将类A的粒度分解为A1,A2

   package com.sun.single;
   
   public class single1 {
       public static void main(String[] args) {
   
           System.out.println(vehicle+"使用单一原则之前");
           Vehicle vehicle = new Vehicle();
           vehicle.run("汽车");
           vehicle.run("飞机");
           vehicle.run("轮船");
       }
   }
   class Vehicle{
       public void run(String vehicle){
           System.out.println(vehicle+"在公路上跑");
       }
   }
   
   

   package com.sun.single;
   
   public class single2 {
       public static void main(String[] args) {
   
           Vehicle1 vehicle1 = new Vehicle1();
           vehicle1.run("汽车");
           Vehicle2 vehicle2 = new Vehicle2();
           vehicle2.runAri("飞机");
           Vehicle3 vehicle3 = new Vehicle3();
           vehicle3.runWater("轮船");
       }
   }
   class Vehicle1{
       public void run(String vehicle){
           System.out.println(vehicle+"在公路上跑");
       }
   }
   class Vehicle2{
       public void runAri(String vehicle){
           System.out.println(vehicle+"在天上跑");
       }
   }
   class Vehicle3{
       public void runWater(String vehicle){
           System.out.println(vehicle+"在水上跑");
       }
   }
   
   

   package com.sun.single;
   
   public class single3 {
       public static void main(String[] args) {
   
           System.out.println(vehicle+"使用单一原则之后");
           Vehicle4 vehicle4 = new Vehicle4();
           vehicle4.run("汽车");
           vehicle4.runAri("飞机");
           vehicle4.runWater("轮船");
           
       }
   }
   class Vehicle4{
       public void run(String vehicle){
           System.out.println(vehicle+"在公路上跑");
       }
       public void runAri(String vehicle){
           System.out.println(vehicle+"在天空上跑");
       }
       public void runWater(String vehicle){
           System.out.println(vehicle+"在水上跑");
       }
   }
   
   

2. 接口隔离原则

   基本介绍

   客户端不应该依赖它不需要的接口，即一个类对另一个类的依赖应该建立在最小的接口上

   package com.sun.segregation;
   
   public class Segregation {
   
   }
   interface interface1{
       void operation1();
       void operation2();
       void operation3();
       void operation4();
       void operation5();
   }
   class B implements interface1{
   
       @Override
       public void operation1() {
   
           System.out.println("B实现了operation1");
       }
   
       @Override
       public void operation2() {
   
           System.out.println("B实现了operation2");
       }
   
       @Override
       public void operation3() {
   
           System.out.println("B实现了operation3");
       }
   
       @Override
       public void operation4() {
   
           System.out.println("B实现了operation4");
       }
   
       @Override
       public void operation5() {
   
           System.out.println("B实现了operation5");
       }
   }
   class D implements interface1{
   
       @Override
       public void operation1() {
   
           System.out.println("D实现了operation1");
       }
   
       @Override
       public void operation2() {
   
           System.out.println("D实现了operation2");
       }
   
       @Override
       public void operation3() {
   
           System.out.println("D实现了operation3");
       }
   
       @Override
       public void operation4() {
   
           System.out.println("D实现了operation4");
       }
   
       @Override
       public void operation5() {
   
           System.out.println("D实现了operation5");
       }
   }
   class A {
       public void depend1(interface1 i){
           i.operation1();
       }
       public void depend2(interface1 i){
           i.operation2();
       }
       public void depend3(interface1 i){
           i.operation3();
       }
   }
   class C {
       public void depend1(interface1 i){
           i.operation1();
       }
       public void depend4(interface1 i){
           i.operation4();
       }
       public void depend5(interface1 i){
           i.operation5();
       }
   }
   

   package com.sun.segregation.improve;
   
   public class Segregation1 {
       public static void main(String[] args) {
           A a = new A();
           a.depend1(new B());
           a.depend2(new B());
           a.depend3(new B());
           C c = new C();
           c.depend1(new D());
           c.depend4(new D());
           c.depend5(new D());
       }
   }
   interface interface1{
       void operation1();
   }
   interface interface2{
       void operation2();
       void operation3();
   }
   interface interface3{
       void operation4();
       void operation5();
   }
   class B implements interface1,interface2{
   
       @Override
       public void operation1() {
   
           System.out.println("B实现了operation1");
       }
   
       @Override
       public void operation2() {
   
           System.out.println("B实现了operation2");
       }
   
       @Override
       public void operation3() {
   
           System.out.println("B实现了operation3");
       }
   
   }
   class D implements interface1,interface3{
   
       @Override
       public void operation1() {
   
           System.out.println("D实现了operation1");
       }
       @Override
       public void operation4() {
   
           System.out.println("D实现了operation4");
       }
   
       @Override
       public void operation5() {
   
           System.out.println("D实现了operation5");
       }
   }
   class A {
       public void depend1(interface1 i){
           i.operation1();
       }
       public void depend2(interface2 i){
           i.operation2();
       }
       public void depend3(interface2 i){
           i.operation3();
       }
   }
   class C {
       public void depend1(interface1 i){
           i.operation1();
       }
       public void depend4(interface3 i){
           i.operation4();
       }
       public void depend5(interface3 i){
           i.operation5();
       }
   }
   

3. 依赖倒转原则

   package com.sun.inversion;
   
   public class DependecyInversion {
       public static void main(String[] args) {
           Persion persion = new Persion();
           persion.receive(new Email());
       }
   }
   
   class Email{
       public String getInfo(){
           return "email:hello world";
       }
   }
   class Persion{
       public void receive(Email email){
           System.out.println(email.getInfo());
       }
   }
   

   package com.sun.inversion.improve;
   
   public class DependecyInversion {
       public static void main(String[] args) {
           Persion persion = new Persion();
           persion.receive(new Email());
           persion.receive(new WeiXin());
       }
   }
   interface IReceive{
       String getInfo();
   }
   class Email implements IReceive{
       public String getInfo(){
           return "email:hello world";
       }
   }
   class WeiXin implements IReceive{
   
       @Override
       public String getInfo() {
           return "WeiXin:hello world";
       }
   }
   
   class Persion{
       public void receive(IReceive receive){
           System.out.println(receive.getInfo());
       }
   }
   

4. 里氏替换原则

   package com.sun.liskov;
   
   public class Liskov {
       public static void main(String[] args) {
   
           A a = new A();
           System.out.println("11-3="+a.func1(11,3));
           System.out.println("1-8="+a.func1(1,8));
           System.out.println("**************************");
           B b = new B();
           System.out.println("11-3="+b.func1(11,3));
           System.out.println("1-8="+b.func1(1,8));
           System.out.println("11+3+9="+b.func2(11,3));
       }
   }
   class A {
       public int func1(int num1,int num2){
           return num1 - num2;
       }
   }
   class B extends A {
       @Override
       public int func1(int a, int b) {
           return a+b;
       }
       public int func2(int a, int b) {
           return func1(a,b)+9;
       }
   }
   
   

   package com.sun.liskov.improve;
   
   public class Liskov {
       public static void main(String[] args) {
   
           A a = new A();
           System.out.println("11-3="+a.func1(11,3));
           System.out.println("1-8="+a.func1(1,8));
           System.out.println("**************************");
           B b = new B();
           System.out.println("11+3="+b.func1(11,3));
           System.out.println("1+8="+b.func1(1,8));
           System.out.println("11+3+9="+b.func2(11,3));
           System.out.println("11-3="+b.func3(11,3));
       }
   }
   
   class base{
   
   }
   class A extends base {
       public int func1(int num1,int num2){
           return num1 - num2;
       }
   }
   
   class B extends base {
       private A a = new A();
       public int func1(int a, int b) {
           return a+b;
       }
       public int func2(int a, int b) {
           return func1(a,b)+9;
       }
       public int func3(int a, int b){
           return this.a.func1(a,b);
       }
   }
   
   

5. 开闭原则

   package com.sun.ocp;
   
   public class Ocp {
       public static void main(String[] args) {
           GraphicEditor graphicEditor = new GraphicEditor();
           graphicEditor.drawShape(new Rectangle());
           graphicEditor.drawShape(new Circle());
       }
   }
   class GraphicEditor {
       public void drawShape(Shape s) {
           if (s.m_type == 1)
               drawRectangle(s);
           else if (s.m_type == 2)
               drawCircle(s);
       }
       public void drawRectangle(Shape r) {
           System.out.println("矩形");
       }
       public void drawCircle(Shape r) {
           System.out.println("圆形");
       }
   }
   class Shape {
       int m_type;
   }
   class Rectangle extends Shape {
       Rectangle() {
           super.m_type = 1;
       }
   }
   class Circle extends Shape {
       Circle() {
           super.m_type = 2;
       }
   }
   

   package com.sun.ocp.improve;
   
   public class Ocp {
       public static void main(String[] args) {
           GraphicEditor graphicEditor = new GraphicEditor();
           graphicEditor.drawShape(new Rectangle());
           graphicEditor.drawShape(new Circle());
           graphicEditor.drawShape(new OtherGraphic());
       }
   }
   
   class GraphicEditor {
       public void drawShape(Shape s) {
           s.draw();
       }
   }
   
   abstract class Shape {
       int m_type;
       public abstract void draw();
   }
   
   class Rectangle extends Shape {
       Rectangle() {
           super.m_type = 1;
       }
   
       @Override
       public void draw() {
           System.out.println("绘制矩形");
       }
   }
   
   class Circle extends Shape {
       Circle() {
           super.m_type = 2;
       }
   
       @Override
       public void draw() {
           System.out.println("绘制圆形");
       }
   }
   class OtherGraphic extends Shape {
   
       OtherGraphic() {
           super.m_type = 4;
       }
       @Override
       public void draw() {
           System.out.println("绘制其他图形");
       }
   }
   

6. 迪米特法则

   package com.sun.demeter;
   
   import java.util.ArrayList;
   import java.util.List;
   
   public class Demeter {
       public static void main(String[] args) {
           SchoolManager schoolManager = new SchoolManager();
           schoolManager.printAllEmployee(new CollegeManager());
       }
   }
   
   class Employee {
       private String id;
   
       public void setId(String id) {
           this.id = id;
       }
   
       public String getId() {
           return id;
       }
   }
   
   class CollegeEmployee {
       private String id;
   
       public void setId(String id) {
           this.id = id;
       }
   
       public String getId() {
           return id;
       }
   }
   
   class CollegeManager {
       public List<CollegeEmployee> getAllEmployee() {
           List<CollegeEmployee> list = new ArrayList<CollegeEmployee>();
           for (int i = 0; i < 10; i++) {
               CollegeEmployee emp = new CollegeEmployee();
               emp.setId("学院员工id:" + i);
               list.add(emp);
           }
           return list;
       }
   }
   
   class SchoolManager {
       public List<Employee> getAllEmpoyee() {
           List<Employee> list = new ArrayList<Employee>();
           for (int i = 0; i < 5; i++) {
               Employee emp = new Employee();
               emp.setId("学校总部员工id:" + i);
               list.add(emp);
           }
           return list;
       }
   
       void printAllEmployee(CollegeManager sub) {
           List<CollegeEmployee> list1 = sub.getAllEmployee();
           System.out.println("*******分公司员工**********");
           for (CollegeEmployee e : list1) {
               System.out.println(e.getId());
           }
           List<Employee> list2 = this.getAllEmpoyee();
           System.out.println("*******学校总部员工*********");
           for (Employee e : list2) {
               System.out.println(e.getId());
           }
       }
   
   }
   

   package com.sun.demeter.improve;
   
   import java.util.ArrayList;
   import java.util.List;
   
   public class Demeter {
       public static void main(String[] args) {
           SchoolManager schoolManager = new SchoolManager();
           schoolManager.printAllEmployee(new CollegeManager());
       }
   }
   
   class Employee {
       private String id;
   
       public void setId(String id) {
           this.id = id;
       }
   
       public String getId() {
           return id;
       }
   }
   
   class CollegeEmployee {
       private String id;
   
       public void setId(String id) {
           this.id = id;
       }
   
       public String getId() {
           return id;
       }
   }
   
   class CollegeManager {
       public List<CollegeEmployee> getAllEmployee() {
           List<CollegeEmployee> list = new ArrayList<CollegeEmployee>();
           for (int i = 0; i < 10; i++) {
               CollegeEmployee emp = new CollegeEmployee();
               emp.setId("学院员工id:" + i);
               list.add(emp);
           }
           return list;
       }
       public void printEmployee() {
           List<CollegeEmployee> list1 = getAllEmployee();
           System.out.println("*******分公司员工**********");
           for (CollegeEmployee e : list1) {
               System.out.println(e.getId());
           }
       }
   }
   
   class SchoolManager {
       public List<Employee> getAllEmpoyee() {
           List<Employee> list = new ArrayList<Employee>();
           for (int i = 0; i < 5; i++) {
               Employee emp = new Employee();
               emp.setId("学校总部员工id:" + i);
               list.add(emp);
           }
           return list;
       }
   
       void printAllEmployee(CollegeManager sub) {
           sub.printEmployee();
           List<Employee> list2 = this.getAllEmpoyee();
           System.out.println("*******学校总部员工*********");
           for (Employee e : list2) {
               System.out.println(e.getId());
           }
       }
   
   }
   

7. 合成复用原则

   尽量使用合成/聚合的方式，而不是使用继承