工厂模式（Factory）-优快云博客

本文介绍了一种使用工厂模式创建不同类型的面包（如鲜面包、咸面包和甜面包）的方法，通过将面包创建过程抽象为独立的工厂类，使得客户端代码更加简洁且易于维护。当新增面包类型时，只需在工厂类中进行修改，而无需改动客户端代码。

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接口

public interface Bread {

    /**
     * 准备
     */
    void prepare();

    /**
     * 烤
     */
    void bake();

    /**
     * 装盒
     */
    void box();
}

bread类型枚举

public enum BreadTypeEnums {

    FRESH("fresh","鲜面包"),
    SALTY("salty","咸面包"),
    SWEET("sweet","甜面包");

    private final String code;
    private final String message;

    BreadTypeEnums(String code, String message){
        this.code = code;
        this.message = message;
    }

    public String getCode() {
        return code;
    }

    public String getMessage() {
        return message;
    }
}

Bread接口实现类

public class FreshBread implements Bread {
    public void prepare() {
        System.out.println("准备鲜面包的原料");
    }

    public void bake() {
        System.out.println("烘烤鲜面包");
    }

    public void box() {
        System.out.println("将烘烤好的鲜面包装盒");
    }
}

public class SaltyBread implements Bread {
    public void prepare() {
        System.out.println("准备咸面包的原料");
    }

    public void bake() {
        System.out.println("烘烤咸面包");
    }

    public void box() {
        System.out.println("将烘烤好的咸面包装盒");
    }
}

public class SweetBread implements Bread {
    public void prepare() {
        System.out.println("准备甜面包原料");
    }

    public void bake() {
        System.out.println("烘烤甜面包");
    }

    public void box() {
        System.out.println("将烘烤好的甜面包装盒");
    }
}

一、客户端代码使用new关键字创建对象

public class BreadStore {

    public Bread orderBread(BreadTypeEnums breadTypeEnums){
        Bread bread = null ;

        if (BreadTypeEnums.FRESH == breadTypeEnums){
            bread = new FreshBread();
        }else if (BreadTypeEnums.SALTY == breadTypeEnums){
            bread = new SaltyBread();
        }else if (BreadTypeEnums.SWEET == breadTypeEnums){
            bread = new SweetBread();
        }else {
            throw new DesignException("该商店暂无此类面包，我们尽快安排敬请期待！");
        }

        bread.prepare();
        bread.bake();
        bread.box();

        return bread;
    }
}

注：在新增新醒面包时需要修改客户端接口

二、分离客户端代码变化部分，创建面包对象的代码到新的类（BreadFactory）

Bread工厂类（BreadFactory）

public class BreadFactory {

    public Bread createBread(BreadTypeEnums breadTypeEnums){
        Bread bread = null ;

        if (BreadTypeEnums.FRESH == breadTypeEnums){
            bread = new FreshBread();
        }else if (BreadTypeEnums.SALTY == breadTypeEnums){
            bread = new SaltyBread();
        }else if (BreadTypeEnums.SWEET == breadTypeEnums){
            bread = new SweetBread();
        }else {
            throw new DesignException("该商店暂无此类面包，我们尽快安排敬请期待！");
        }

        return bread;
    }
}

public class BreadStore {

    private BreadFactory breadFactory;

    public BreadStore(BreadFactory breadFactory){
        this.breadFactory = breadFactory;
    }

    public Bread orderBread(BreadTypeEnums breadTypeEnums){
        Bread bread = breadFactory.createBread(breadTypeEnums);

        bread.prepare();
        bread.bake();
        bread.box();

        return bread;
    }
}

三、