工厂模式

1. 工厂模式

先定义一个接口

package Interface;

public interface Shape {
    void draw();
}

再定义三个实体类实现接口

 //class1
package Interface;

public class CirCle implements Shape{

    @Override
    public void draw() {
        System.out.println("圆形车");
    }
}

//class2
package Interface;

public class Square implements Shape {

    @Override
    public void draw() {
        System.out.println("正方形车");
    }
}

//class3
package Interface;

public class Rectangle implements Shape{

    @Override
    public void draw() {
        System.out.println("长方形车");
    }
}

创建一个工厂类，生成基于给定信息的实体类对象

package Factory;

import Interface.CirCle;
import Interface.Rectangle;
import Interface.Shape;
import Interface.Square;

public class ShapeFactory {
    public Shape getshape(String shapetype){
        if(shapetype == null)
        {
            return  null;
        }else if(shapetype.equalsIgnoreCase("CIRCLE") )
        {
            return new CirCle();
        }else if(shapetype.equalsIgnoreCase("Rectangle"))
        {
            return new Rectangle();
        }else if (shapetype.equalsIgnoreCase("SQUARE"))
        {
            return  new Square();
        }
        return null;
    }
}

/**
     * Compares this {@code String} to another {@code String}, ignoring case
     * considerations.  Two strings are considered equal ignoring case if they
     * are of the same length and corresponding characters in the two strings
     * are equal ignoring case.
     *
     * <p> Two characters {@code c1} and {@code c2} are considered the same
     * ignoring case if at least one of the following is true:
     * <ul>
     *   <li> The two characters are the same (as compared by the
     *        {@code ==} operator)
     *   <li> Applying the method {@link
     *        java.lang.Character#toUpperCase(char)} to each character
     *        produces the same result
     *   <li> Applying the method {@link
     *        java.lang.Character#toLowerCase(char)} to each character
     *        produces the same result
     * </ul>
     *
     * @param  anotherString
     *         The {@code String} to compare this {@code String} against
     *
     * @return  {@code true} if the argument is not {@code null} and it
     *          represents an equivalent {@code String} ignoring case; {@code
     *          false} otherwise
     *
     * @see  #equals(Object)
     */
     
//顺便开启读equalsIgnoreCase()方法的源码
public boolean equalsIgnoreCase(String anotherString) {
        return (this == anotherString) ? true
                : (anotherString != null)
                && (anotherString.value.length == value.length)
                && regionMatches(true, 0, anotherString, 0, value.length);
    }

创建一个测试用例，使用“工厂类”来获取Shape对象，同时它将向工厂类传递信息以获取它所需要的类型

import Factory.ShapeFactory;
import Interface.Shape;

public class TestFactoryDemo {
    public static void main(String[] args) {
        ShapeFactory factory = new ShapeFactory();

        Shape shape1 = factory.getshape("CIRCLE");
        shape1.draw();

        Shape shape2 = factory.getshape("RECTANGLE");
        shape2.draw();

        Shape shape3 = factory.getshape("SQUARE");
        shape3.draw();

    }
}