设计模式学习

1 策略设计模式

package thinkJava;

/*
 * 策略设计模式
 * 像本例一样，能够根据所传递的参数对象的不同而具有不同的行为的方法。
 * Processor对象就是一个策略，有3中不同的策略应用到了String类型的对象上。
 */
import java.util.Arrays;

class Processor {
    public String name() {
        return getClass().getSimpleName();
    }

    Object process(Object input) {
        return input;
    }
}

class Upcase extends Processor {
    String process(Object input) {
        return ((String) input).toUpperCase();
    }
}

class Downcase extends Processor {
    String process(Object input) {
        return ((String) input).toLowerCase();
    }
}

class Splitter extends Processor {
    String process(Object input) {
        return Arrays.toString(((String) input).split(" "));
    }
}

public class Apply {

    public static void process(Processor p, Object s) {
        System.out.println("Using Processor " + p.name());
        System.out.println(p.process(s));
    }

    public static String s = "Disagreemment with beliefs is by definition incorrect";

    public static void main(String[] args) {
        process(new Upcase(), s);
        process(new Downcase(), s);
        process(new Splitter(), s);
    }

}

 

 

运行结果

 2 单例模式

package singleton;

class Soup {
    private Soup() {
    }

    private static Soup pSoup = new Soup();

    public static Soup getInstance() {
        return pSoup;
    }

    public void f() {
        System.out.println("f() in pSoup is working");
    }
}

public class Lunch {
    static void testSingleton() {
        Soup.getInstance().f();
    }

    public static void main(String[] args) {
        testSingleton();
    }
}

运行结果：

f() in pSoup is working

 3 代理模式

package reusing;

public class SpaceShipControls {
    void up(int velocity){
        
    }
    void down(int velocity){
        
    }
    void left(int velocity){
        
    }
    void right(int velocity){
        
    }
    void forward(int velocity){
        
    }
    void back(int velocity){
        
    }
    void turnBoost(){
        
    }
}

代理模式开始：

 

package reusing;
/*
 * SpaceShip并非真正的SpaceShipControls类型。
 * 可以采用中庸之道，介于组合和继承之间的模式
 * SpaceShip包含SpaceShipControls，同时，SpaceShipControls
 * 的所有方法在SpaceShip中都暴露出来了。代理解决了此问题。
 */
public class SpaceShipDelegation {
    private String name;
    private SpaceShipControls controls = new SpaceShipControls();
    public SpaceShipDelegation(String name){
        this.name = name;
    }
    public void back(int velocity){
        controls.back(velocity);
    }
    public void forward(int velocity){
        controls.forward(velocity);
    }
    public void down(int velocity){
        controls.down(velocity);
    }
    public void up(int velocity){
        controls.up(velocity);
    }
    public void right(int velocity){
        controls.right(velocity);
    }
    public void left(int velocity){
        controls.left(velocity);
    }
    public void turnboBoost(){
        controls.turnBoost();
    }
    public static void main(String[] args){
        SpaceShipDelegation protector = new SpaceShipDelegation("NAEA Protector");
        protector.forward(100);
    }
}

4  工厂模式

 

package ploymorphism;

import java.util.Random;

public class Shape {
    public void draw() {

    }

    public void erase() {

    }
}

public class Square extends Shape {
    public void draw() {
        System.out.println("Square draw()");
    }

    public void erase() {
        System.out.println("Square erase()");
    }
}

public class Circle extends Shape {
    public void draw() {
        System.out.println("Circle draw()");
    }

    public void erase() {
        System.out.println("Circle erase()");
    }
}

public class Triangle extends Shape {
    public void draw() {
        System.out.println("Triangle draw()");
    }

    public void erase() {
        System.out.println("Triangle erase()");
    }
}

public class RandomShapeGenerator {
    private Random rand = new Random(47);  //工厂模式

    public Shape next() {
        switch (rand.nextInt(3)) {
        default:
        case 0:
            return new Circle();
        case 1:
            return new Square();
        case 2:
            return new Triangle();
        }
    }
}

public class Shapes {
    private static RandomShapeGenerator gen = new RandomShapeGenerator();

    public static void main(String[] args) {
        Shape[] s = new Shape[9];
        for (int i = 0; i < s.length; i++) {
            s[i] = gen.next();
        }
        for (Shape shp : s) {
            shp.draw();
        }
    }
}

/*
 * Triangle draw()
 * Triangle draw()
 * Square draw()
 * Triangle draw()
 * Square draw()
 * Triangle draw()
 * Square draw()
 * Triangle draw()
 * Circle draw()
 */