【软件设计】工厂模式之反射技术+读取配置文件

一、实验目的

1. 理解面向对象设计原则和常用设计模式；
2. 理解并掌握工厂模式的概念和实现；
3. 理解并掌握抽象工厂模式的概念和实现；
4. 理解用反射技术+配置文件对工厂模式进行改进的方法

二、工厂模式实验

利用“反射技术+读取配置文件”的方法对简易计算器程序做改进

1、工厂模式与简单工厂模式的区别

简单工厂模式：一个工厂创建多个产品
工厂模式：每个产品都有对应的工厂进行生产，使用Factory模式替代new创建对象
抽象工厂模式：使用迭代模式创建对象

2、Properties类（介绍）

java中提供了配置文件的操作类Properties，Properties常用方法：

//设置properties键值对
properties.setProperty(String key, String value);

//获取properties值
properties.getProperty(String key);

//从输入流中读取属性列表（键值对）
properties.load(InputStream inStream);
properties,load(new FileInputStream("路径")
//按简单的面向行的格式从输入字符流中读取属性列表（键值对）
properties.load(Reader reader);

//将XML文档所表示的所有属性加载到properties中
properties.loadFromXML(InputStream in);

//以适合使用 load(InputStream) 方法加载到 Properties 表中的格式，将此 Properties 表中的属性列表（键值对）写入输出流
properties.store(OutputStream out, String comments);

//以适合使用 load(Reader) 方法的格式，将此 Properties 表中的属性列表（键值对）写入输出字符
properties.store(Writer writer, String comments);
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3、总结：通过读取配置文件的形式可以实现代码的深层次解耦，在java编程中，配置文件的重要性更是不言而喻。java编程有一条不成文的规定就是：“约定大于配置，配置大于代码”意思就是能用约定的就不去配置，能用配置文件搞定的就不去写代码。

4、代码

IFactory.java

package pac01;

interface IFactory {
    Operation createOperation(String A,String B);
}

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FactoryAdd.java

package pac01;
class FactoryAdd implements IFactory {
    @Override
    public Operation createOperation(String A,String B) {
        return new OperationAdd();
    }

}

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FactoryDiv.java

package pac01;
class FactoryDiv implements IFactory{
    @Override
    public Operation createOperation(String A,String B) {
        return new OperationDiv();
    }
}

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FactoryMul.java

package pac01;
class FactoryMul implements IFactory {
    @Override
    public Operation createOperation(String A,String B) {
        return new OperationMul();
    }
}

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FactorySub.java

package pac01;
class FactorySub implements IFactory {
    @Override
    public Operation createOperation(String A,String B) {
        return new OperationSub();
    }
}
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Properties.java

package io;
import java.io.InputStream;

public class Properties {
    public static void main (String[] args){
//        获取class的包装类class
        Class propertiesClass =  Properties.class;

//        类加载器类：负责加载类的对象
        ClassLoader classLoader = propertiesClass.getClassLoader();

//        get得到资源作为文件流 （获取文件流）
        InputStream inputStream = classLoader.getResourceAsStream("jdb.properties");

        //        System.out.println(inputStream);

    }
}

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jdbc.properties

+=pac01.FactoryAdd
-=pac01.FactorySub
*=pac01.FactoryMul
/=pac01.FactoryDiv
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Test.java

package pac01;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.Scanner;

public class Test{
        public static void main(String[] args) throws IOException, ClassNotFoundException, InstantiationException, IllegalAccessException {
                try {
                        Scanner input = new Scanner(System.in);
                        System.out.print("请输入数字A: ");
                        String strNumberA = input.nextLine();
                        System.out.print("请输入+-*/: ");
                        String strType = input.nextLine();
                        System.out.print("请输入数字B: ");
                        String strNumberB = input.nextLine();
                        Properties properties = new Properties();
                        InputStream is = new FileInputStream(new File("src/jdbc.properties"));
                        properties.load(is);
                        is.close();
                        String className = properties.getProperty(strType);
                        IFactory factory = (IFactory) Class.forName(className).newInstance();
                        Operation oper = factory.createOperation(strNumberA,strNumberB);
                        System.out.println("结果为" + oper.getResult(strNumberA, strNumberB));
                } catch (Exception e) {
                        System.out.println("除数不能为零");
                }
        }
}
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其余代码与上期相同，详见软件工程综合实践】工厂模式之简易四则运算器（完整代码）

三、蛋糕店升级版

1、Diagrams

2、代码

BananaCakeFactory.java

public class BananaCakeFactory implements IFactory{
    @Override
    public Cake createCake(String type){
        return new BananaCake();
    }
}
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CheeseCakeFactory.java

class CheeseCakeFactory implements IFactory{
    @Override
    public Cake createCake(String type){
        return new CheeseCake();
    }
}
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ChocolateCakeFactory.java

class ChocolateCakeFactory implements IFactory{
    @Override
    public Cake createCake(String type){
        return new ChocolateCake();
    }

}

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LemonCakeFactory、StrawberryCakeFactory类似

IFactory.java

interface IFactory {
    Cake createCake(String type);
}

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cake.properties

Strawberry=pac01.StrawberryCake
Lemon=pac01.LemonCake
Banana=pac01.BananaCake
Chocolate=pac01.ChocolateCake
Cheese=pac01.CheeseCake


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BananaCake.java

package pac01;
public class BananaCake extends Cake {
    @Override
    public void addMilk() {
        System.out.println("给蛋糕加牛奶！");
    }
    @Override
    public void addFlour() {
        System.out.println("给蛋糕加面粉！");
    }
    @Override
    public String getName() {
        return "香蕉蛋糕";
    }
}

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CheeseCake.java

package pac01;
public class CheeseCake extends Cake{
    @Override
    public void addMilk() {
        System.out.println("给蛋糕加牛奶！");
    }
    @Override
    public void addFlour() {
        System.out.println("给蛋糕加面粉！");
    }
    @Override
    public String getName() {
        return "芝士蛋糕";
    }
}

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ChocolateCake.java

package pac01;
public class ChocolateCake extends Cake{
    @Override
    public void addMilk() {
        System.out.println("给蛋糕加牛奶！");
    }
    @Override
    public void addFlour() {
        System.out.println("给蛋糕加面粉！");
    }
    @Override
    public String getName() {
        return "巧克力蛋糕";
    }
}

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Client.java

package pac01;

import sun.security.krb5.internal.crypto.CksumType;
import java.io.*;
import java.util.Properties;
import java.util.Scanner;
public class Client {
    public static void main(String[] args) throws IOException, ClassNotFoundException, InstantiationException, IllegalAccessException {
        Scanner input =new Scanner(System.in);
        CakeStore cakeStore = new CakeStore();
        cakeStore.welcome();

        String type = input.nextLine();

        Properties properties = new Properties();
        InputStream is = new FileInputStream(new File("src/cake.properties"));
        properties.load(is);
        is.close();
        String className = properties.getProperty(type);
        IFactory factory = (IFactory) Class.forName(className).newInstance();
        Cake cake = factory.createCake(type);
        cake.addMilk();
        cake.addFlour();
        System.out.println(cake.getName(type)+"新鲜出炉~");
        cakeStore.goodbye();
    }
}


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