Java实现对文件的加密（解密）

java实现对文件的加密或者解密，可设定加密KEY。

以下demo是对文件夹内文件批量加密解密

package cn.test;

import java.io.File;
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 java.util.ArrayList;
import java.util.List;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;

public class TestDES {
	private Key key;

	private static String fileTail = ".bcp";// 文件结尾

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

	/**
	 * 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) {
			System.out.println();
			cos.write(buffer, 0, r);
		}
		cos.close();
		out.close();
		is.close();
	}

	/**
	 * 递归读取文件夹内文件
	 * 
	 * @param fileList
	 *            new一个list
	 * @param strPath
	 *            文件夹路径
	 * @return 文件夹内文件list
	 */
	public static List<File> getFileList(List<File> fileList, String strPath) {
		File dir = new File(strPath);
		File[] files = dir.listFiles(); // 该文件目录下文件全部放入数组
		if (files != null) {
			for (int i = 0; i < files.length; i++) {
				String fileName = files[i].getName();
				if (files[i].isDirectory()) { // 判断是文件还是文件夹
					getFileList(fileList, files[i].getAbsolutePath()); // 获取文件绝对路径
				} else if (fileName.endsWith(fileTail)) { // 判断文件名结尾
					fileList.add(files[i]);
				} else {
					continue;
				}
			}
		}
		return fileList;
	}

	public static void main(String[] args) throws Exception {
		Long aaa = System.currentTimeMillis();
		TestDES td = new TestDES("888888");
		List<File> fileList = getFileList(new ArrayList<File>(), "D:/aaa/mac");
		String path = null;
		for (File file : fileList) {
			path = file.getAbsolutePath();
			td.encrypt(path, path.replace(fileTail, "_1" + fileTail)); // 加密
			// file.delete();
		}
		Long bbb = System.currentTimeMillis();
		Long temp = bbb - aaa;
		fileList = getFileList(new ArrayList<File>(), "D:/aaa/mac");
		for (File file : fileList) {
			path = file.getAbsolutePath();
			td.decrypt(path, path.replace("_1" + fileTail, "_0" + fileTail)); // 解密
			// file.delete();
		}
		Long ccc = System.currentTimeMillis();
		System.out.println("加密耗时：" + temp);
		System.out.println("解密耗时：" + (ccc - bbb));
	}
}