• 介绍

　　　　外观模式实现了通过访问外观类的简单接口就可以操作系统，用户不必与复杂的子系统进行交互。本质就是类的封装。

　　　　为实现代码的重用性，将加密操作分为三个代码块，读取FileReader、加密CipherMachine、保存FileWriter。将某一文件的内容读取出来后，内容进行加密，并将加密的新内容保存到另外一个文件中。

• 类图

　　

• 代码

public class FileReader {
    public String read(String path){
        FileInputStream fis=null;
        try {
            fis=new FileInputStream(path);
            byte[]b=new byte[1024];
            int len=0;
            StringBuffer sb=new StringBuffer();
            while((len=fis.read(b))!=-1){
                sb.append(new String(b,0,len));
            }
            return sb.toString();
        }catch (FileNotFoundException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }finally {
            try {
                fis.close();
            }catch (IOException e){
                e.printStackTrace();
            }
        }
        return "";
    }
}

public class FileWriter {
    public void write(String content,String path){
        FileOutputStream fos=null;
        try {
            fos=new FileOutputStream(path);
            fos.write(content.getBytes());
        }catch (FileNotFoundException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }
        finally {
            try {
                fos.close();
            }catch (IOException e){
                e.printStackTrace();
            }
        }

    }
}

public class CipherMachine {
    public String Encrypt(String str){
        char[]arr=str.toCharArray();
        StringBuffer sb=new StringBuffer();
        for (char c:
             arr) {
            sb.append(c+1);
        }
        return sb.toString();
    }
}

public class EncryptFacade {
    private FileReader fileReader;
    private CipherMachine cipherMachine;
    private FileWriter fileWriter;
    public EncryptFacade(){
        fileReader=new FileReader();
        cipherMachine=new CipherMachine();
        fileWriter=new FileWriter();
    }
    public void FileEncrypt(String source,String target){
        String str=fileReader.read(source);
        String enStr=cipherMachine.Encrypt(str);
        fileWriter.write(enStr,target);
    }
}

public class Main {
    public static void main(String[] args) {
        EncryptFacade encryptFacade=new EncryptFacade();
        encryptFacade.FileEncrypt("D:\\facade\\source.txt","D:\\facade\\target.txt");
    }
}