练习.加密和解密

1.简单加密&解密

 1 package com.java7.myencrypt.main;
 2 
 3 import java.io.File;
 4 import java.io.FileInputStream;
 5 import java.io.FileNotFoundException;
 6 import java.io.FileOutputStream;
 7 import java.io.IOException;
 8 
 9 public class MyEncrypt {
10     public static void main(String[] args) {
11         try {
12             File inFile = new File("inFile.txt");
13             File outFile = new File("outFile.txt");
14             
15             if (inFile.createNewFile()) {
16                 System.out.println("File is created!");
17             } else {
18                 System.out.println("File already exists.");
19             }
20             
21             FileInputStream fis = new FileInputStream(inFile);
22             FileOutputStream fos = new FileOutputStream(outFile);
23 
24             System.out.println(fis.available());
25             int length = fis.available();
26             for(int i = 0; i < length; i++) {
27                 fos.write(fis.read()+100);
28             }
29         } catch (FileNotFoundException e) {
30             // TODO Auto-generated catch block
31             e.printStackTrace();
32         } catch (IOException e) {
33             // TODO Auto-generated catch block
34             e.printStackTrace();
35         }
36     }
37 }

 1 package com.java7.mydecrypt.main;
 2 
 3 import java.io.File;
 4 import java.io.FileInputStream;
 5 import java.io.FileNotFoundException;
 6 //import java.io.FileOutputStream;
 7 import java.io.IOException;
 8 
 9 public class MyDecrypt {
10     public static void main(String[] args) {
11         try {
12             File dcFile = new File("outFile.txt");
13 //            File dcNewFile = new File("dcNewFile.txt");
14             
15             if(dcFile.exists()) {
16                 System.out.println("File already exists.");
17             } else {
18                 System.out.println("File not found.");
19             }
20 //            if(dcNewFile.createNewFile()){
21 //                System.out.println("File is created!");
22 //            } else {
23 //                System.out.println("File already exists.");
24 //            }
25             
26             FileInputStream fis = new FileInputStream(dcFile);
27 //            FileOutputStream fos = new FileOutputStream(dcNewFile);
28 
29             System.out.println(fis.available());
30             int length = fis.available();
31             for(int i = 0; i < length; i++) {
32                 System.out.print((char)(fis.read()-100));
33 //                fos.write((fis.read()-100));
34             }
35         } catch (FileNotFoundException e) {
36             // TODO Auto-generated catch block
37             e.printStackTrace();
38         } catch (IOException e) {
39             // TODO Auto-generated catch block
40             e.printStackTrace();
41         }
42     }
43 }