java 实现文件内容的加密和解密

package com.umapp.test;

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 TestDES {

  Key key;

  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();

  }

  public static void main(String[] args) throws Exception {

    TestDES td = new TestDES("aaa");

    td.encrypt("e:/r.txt", "e:/r解密.txt"); //加密

    td.decrypt("e:/r解密.txt", "e:/r1.txt"); //解密 

  }

}
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java 实现文件内容的加密和解密

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