设计模式--工厂方法模式

实验3:工厂方法模式

本次实验属于模仿型实验,通过本次实验学生将掌握以下内容:

1、理解工厂方法模式的动机,掌握该模式的结构;

2、能够利用工厂方法模式解决实际问题。

[实验任务]:加密算法

目前常用的加密算法有DES(Data Encryption Standard)和IDEA(International Data Encryption Algorithm)国际数据加密算法等,请用工厂方法实现加密算法系统。

类图设计模式--工厂方法模式_第1张图片
运行效果

设计模式--工厂方法模式_第2张图片

源代码
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class DES implements Encryption
{
    private SecretKey secretKey;

    public DES()
    {
        try
        {
            KeyGenerator keyGenerator = KeyGenerator.getInstance("DES");
            secretKey = keyGenerator.generateKey();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    //DES加密
    @Override
    public String encrypt(String text)
    {
        try
        {
            Cipher cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
            byte[] encryptedBytes = cipher.doFinal(text.getBytes(StandardCharsets.UTF_8));
            return Base64.getEncoder().encodeToString(encryptedBytes);
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return null;
        }
    }

    //DES解密
    @Override
    public String decrypt(String ciphertext)
    {
        try
        {
            Cipher cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(ciphertext));
            return new String(decryptedBytes, StandardCharsets.UTF_8);
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return null;
        }
    }
}


public class DESFactory implements EncryptionFactory
{
    @Override
    public Encryption createEncryption()
    {
        return new DES();
    }
}


public interface Encryption
{
    String encrypt(String text);

    String decrypt(String ciphertext);
}


public interface EncryptionFactory
{
    Encryption createEncryption();
}



import java.util.Scanner;

public class FactoryMethod
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入要加密的文本:");
        String text = sc.next();

        EncryptionFactory factory = null;

        System.out.println("请输入加密算法编号:\n" +
                "1、DES加密  2、IDEA加密");
        int choose = sc.nextInt();
        if (choose == 1)
        {
            //DES加密
            factory = new DESFactory();
            System.out.println("DES加密");
        } else if (choose == 2)
        {
            //IDEA加密
            factory = new IDEAFactory();
            System.out.println("IDEA加密");
        }

        Encryption encryptionAlgorithm = factory.createEncryption();
        String encryptedText = encryptionAlgorithm.encrypt(text);
        String decryptedText = encryptionAlgorithm.decrypt(encryptedText);
        System.out.println("原文本:" + text);
        System.out.println("加密后:" + encryptedText);
        System.out.println("解密后:" + decryptedText);
    }
}


import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.nio.charset.StandardCharsets;
import java.security.Security;
import java.util.Base64;

public class IDEA implements Encryption
{
    private SecretKey secretKey;

    static
    {
        // 添加Bouncy Castle提供程序
        Security.addProvider(new BouncyCastleProvider());
    }

    public IDEA()
    {
        try
        {
            KeyGenerator keyGenerator = KeyGenerator.getInstance("IDEA", "BC");
            secretKey = keyGenerator.generateKey();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    @Override
    public String encrypt(String text)
    {
        try
        {
            // 创建一个IDEA加密器
            Cipher cipher = Cipher.getInstance("IDEA/ECB/PKCS5Padding", "BC");
            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
            byte[] encryptedBytes = cipher.doFinal(text.getBytes());
            return Base64.getEncoder().encodeToString(encryptedBytes);
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return null;
        }
    }

    @Override
    public String decrypt(String ciphertext)
    {
        try
        {
            Cipher cipher = Cipher.getInstance("IDEA/ECB/PKCS5Padding", "BC");
            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            byte[] encryptedBytes = Base64.getDecoder().decode(ciphertext);
            return new String(cipher.doFinal(encryptedBytes), StandardCharsets.UTF_8);
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return null;
        }
    }
}


public class IDEAFactory implements EncryptionFactory
{
    @Override
    public Encryption createEncryption()
    {
        return new IDEA();
    }
}

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