DES 文件加密解密

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;

public class DocumentDES {

    Key key;

    public DocumentDES(String str) {
        getKey(str);// 生成密匙
    }

    /**
     * 
     * @功能：根据参数生成KEY
     * @参数：
     * @param strKey
     * @返回参数：void
     * @修改人:
     * @修改时间：
     */
    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);
        }
    }

  
    /**
     * 
     * @功能：文件file进行加密并保存目标文件destFile中
     * @参数：
     * @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
     * @修改人:
     * @修改时间：
     */
    public void encrypt(String file, String destFile) throws Exception {
        Cipher cipher = Cipher.getInstance("DES");
        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();
    }

    /**
     * 
     * @功能： 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 dest
     *            解密后存放的文件名 如c:/ test/解密后文件.txt
     * @返回参数：void
     * @修改人:
     * @修改时间：
     */
    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) {
            System.out.println();
            cos.write(buffer, 0, r);
        }
        cos.close();
        out.close();
        is.close();
    }

    public static void main(String[] args) throws Exception {
        DocumentDES td = new DocumentDES("aaa");
        td.encrypt("g:/待加密文件.xlsx", "g:/加密文件.xlsx"); // 加密
        td.decrypt("g:/加密文件.xlsx", "g:/解密文件.xlsx"); // 解密
    }
}