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

【推广】 免费学中医，健康全家人
原文地址：https://www.cnblogs.com/striver20/p/13602013.html