使用java自带des加密算法实现文件加密和字符串加密

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;
public class DesTool {
 private static final String PASSKEY = "afasdf";
 private static final String DESKEY = "asfsdfsdf";
 /**
  * @Comments ：对文件进行加密
  * @param filePath  要加密的文件路径
  * @param fileName 文件
  * @param mode 加密模式  加密：Cipher.ENCRYPT_MODE 解密：Cipher.DECRYPT_MODE
  * @return
  */
 public static String encoderOrdecoder(String filePath, String fileName, int mode) {

  InputStream is = null;
  OutputStream out = null;
  CipherInputStream cis = null;

  try {
   SecureRandom sr = new SecureRandom();
   DESKeySpec dks = new DESKeySpec(DESKEY.getBytes());
   SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
   SecretKey securekey = keyFactory.generateSecret(dks);
   IvParameterSpec iv = new IvParameterSpec(PASSKEY.getBytes());
   Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
   cipher.init(mode, securekey, iv, sr);

   File encoderFile = new File(filePath + File.separator + "encoder");
   if (!encoderFile.exists()) {
    encoderFile.mkdir();
   }

   is = new FileInputStream(filePath + File.separator + fileName);
   out = new FileOutputStream(filePath + File.separator + "encoder"
     + File.separator + fileName);

   cis = new CipherInputStream(is, cipher);
   byte[] buffer = new byte[1024];
   int r;
   while ((r = cis.read(buffer)) > 0) {
    out.write(buffer, 0, r);
   }

  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    if (is != null) {
     is.close();
    }
    if (cis != null) {
     cis.close();
    }
    if (out != null) {
     out.close();
    }
   } catch (Exception e1){

   }
  }
  return filePath + File.separator + "encoder" + File.separator
    + fileName;
 }

/**@Comments ：对字符串进行加密
 * @param src 源字符串
 * @param mode 加密模式  加密：Cipher.ENCRYPT_MODE 解密：Cipher.DECRYPT_MODE
 * @return
 */
public static String encoderOrdecoder( String src, int mode) {
  String tag="";
  InputStream is = null;
  OutputStream out = null;
  CipherInputStream cis = null;

  try {
   SecureRandom sr = new SecureRandom();
   DESKeySpec dks = new DESKeySpec(DESKEY.getBytes());
   SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
   SecretKey securekey = keyFactory.generateSecret(dks);
   IvParameterSpec iv = new IvParameterSpec(PASSKEY.getBytes());
   Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
   cipher.init(mode, securekey, iv, sr);
   cis = new CipherInputStream(new ByteArrayInputStream(src.getBytes()) , cipher);
   out=new ByteArrayOutputStream();
   byte[] buffer = new byte[1024];
   int r;
   while ((r = cis.read(buffer)) > 0) {
    out.write(buffer, 0, r);
   }
   tag=out.toString();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    if (is != null) {
     is.close();
    }
    if (cis != null) {
     cis.close();
    }
    if (out != null) {
     out.close();
    }
   } catch (Exception e1){

   }
  }
  return tag;
 }
 public static void main(String[] args) {
  System.out.println("aaa"); 
  String t=encoderOrdecoder("aaa", Cipher.ENCRYPT_MODE );
  System.out.println(t); 
  System.out.println(encoderOrdecoder(t, Cipher.DECRYPT_MODE ));
 }
}