文件上传加密、下载解密

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import java.io.*;
import java.security.Key;
import java.security.SecureRandom;
import java.util.UUID;

public class FileDES {
 Key key;
 private volatile static FileDES instance;
 private FileDES(){
  System.out.println("Singleton has loaded");
  getKey("abcdefg");
 }
 public static FileDES getInstance(){
  if(instance==null){
   synchronized (FileDES.class){
    if(instance==null){
     instance=new FileDES();
    }
   }
  }
  return instance;
 }
   /** 
   * 根据参数生成KEY 
   */ 
   public void getKey(String strKey) { 
     try { 
         KeyGenerator _generator = KeyGenerator.getInstance("DES"); 
         _generator.init(new SecureRandom(strKey.getBytes())); 
         this.key = _generator.generateKey(); 
         _generator = null; 
     } catch (Exception e) { 
         throw new RuntimeException("Error initializing SqlMap class. Cause: " + e); 
     } 
   } 

   /** 
   * 文件file进行加密并保存目标文件destFile中 
   * 
   * @param file   要加密的文件 如c:/test/srcFile.txt 
   * @param destFile 加密后存放的文件名 如c:/加密后文件.txt 
   */ 
   public void encrypt(String file, String destFile) throws Exception { 
     Cipher cipher = Cipher.getInstance("DES"); 
     // cipher.init(Cipher.ENCRYPT_MODE, getKey()); 
     cipher.init(Cipher.ENCRYPT_MODE, this.key); 
     InputStream is = new FileInputStream(file); 
     OutputStream out = new FileOutputStream(destFile); 
     CipherInputStream cis = new CipherInputStream(is, cipher); 
     byte[] buffer = new byte[1024]; 
     int r; 
     while ((r = cis.read(buffer)) > 0) { 
         out.write(buffer, 0, r); 
     } 
     cis.close(); 
     is.close(); 
     out.close(); 
   } 
   /** 
   * 文件采用DES算法解密文件 
   * 
   * @param file 已加密的文件 如c:/加密后文件.txt 
   *         * @param destFile 
   *         解密后存放的文件名 如c:/ test/解密后文件.txt 
   */ 
   public void decrypt(String file, String dest) throws Exception { 
     Cipher cipher = Cipher.getInstance("DES"); 
     cipher.init(Cipher.DECRYPT_MODE, this.key); 
     InputStream is = new FileInputStream(file); 
     OutputStream out = new FileOutputStream(dest); 
     CipherOutputStream cos = new CipherOutputStream(out, cipher); 
     byte[] buffer = new byte[1024]; 
     int r; 
     while ((r = is.read(buffer)) >= 0) { 
         cos.write(buffer, 0, r); 
     } 
     cos.close(); 
     out.close(); 
     is.close(); 
   }

 /**
  * 上传加密(使用中)
  * @param file
  * @param destFile
  * @throws Exception
  */
 public void encrypt(File file, String destFile) throws Exception {
  Cipher cipher = Cipher.getInstance("DES");
  // cipher.init(Cipher.ENCRYPT_MODE, getKey());
  cipher.init(Cipher.ENCRYPT_MODE, this.key);
  InputStream is = new FileInputStream(file);
  OutputStream out = new FileOutputStream(destFile);
  CipherInputStream cis = new CipherInputStream(is, cipher);
  byte[] buffer = new byte[1024];
  int r;
  while ((r = cis.read(buffer)) > 0) {
   out.write(buffer, 0, r);
  }
  cis.close();
  is.close();
  out.close();
 }

 /**
  * 下载解密（使用中）
  * @param is
  * @return
  * @throws Exception
  */
 public String decrypt(InputStream is) throws Exception {
    String returnPath="";
  Cipher cipher = Cipher.getInstance("DES");
  cipher.init(Cipher.DECRYPT_MODE, this.key);

  File temp = File.createTempFile(UUID.randomUUID().toString(), "");
  OutputStream out = new FileOutputStream(temp);
  CipherOutputStream cos = new CipherOutputStream(out, cipher);

  //ByteArrayInputStream  res=new ByteArrayInputStream (((OutputStream)cos).toByteArray());
  byte[] buffer = new byte[1024];
  int r;
  while ((r = is.read(buffer)) >= 0) {
   cos.write(buffer, 0, r);
  }
  returnPath=temp.getAbsolutePath();
  cos.close();
  out.close();
  is.close();
  return returnPath;
 }
 public static void main(String[] args) throws Exception {
   FileDES td = FileDES.getInstance();
     //td.encrypt("D:\\1.png", "D:\\2.png"); //加密 
    td.decrypt("D:\\111.jrxml", "D:\\112.jrxml"); //解密
     
   } 
}