如何通过JAVA对电脑中的文本文档进行加密,最好能够详细的说一下！

package com.test.zc;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import javax.crypto.Cipher;

public class RSAEncrypt {

private KeyPairGenerator keyPairGen;

private KeyPair keyPair;

private RSAPrivateKey privateKey;

private RSAPublicKey publicKey;

public RSAEncrypt() {
try {
keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(512);
keyPair = keyPairGen.generateKeyPair();
// Generate keys
privateKey = (RSAPrivateKey) keyPair.getPrivate();
publicKey = (RSAPublicKey) keyPair.getPublic();
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

public static void main(String[] args) {
RSAEncrypt encrypt = new RSAEncrypt();
File file = new File(
"C:\\Documents and Settings\\Administrator.DCB5E0D91E0D436\\桌面\\test.txt");
File newFile = new File(
"C:\\Documents and Settings\\Administrator.DCB5E0D91E0D436\\桌面\\test1.txt");
encrypt.encryptFile(encrypt, file, newFile);
File file1 = new File(
"C:\\Documents and Settings\\Administrator.DCB5E0D91E0D436\\桌面\\test1.txt");
File newFile1 = new File(
"C:\\Documents and Settings\\Administrator.DCB5E0D91E0D436\\桌面\\test2.txt");
encrypt.decryptFile(encrypt, file1, newFile1);
}

public void encryptFile(RSAEncrypt encrypt, File file, File newFile) {
try {
InputStream is = new FileInputStream(file);
OutputStream os = new FileOutputStream(newFile);

byte[] bytes = new byte[53];
while (is.read(bytes) > 0) {
byte[] e = encrypt.encrypt(encrypt.publicKey, bytes);
bytes = new byte[53];
os.write(e, 0, e.length);
}
os.close();
is.close();
System.out.println("write success");
} catch (Exception e) {
e.printStackTrace();
}
}

public void decryptFile(RSAEncrypt encrypt, File file, File newFile) {
try {
InputStream is = new FileInputStream(
new File(
"C:\\Documents and Settings\\Administrator.DCB5E0D91E0D436\\桌面\\test1.txt"));
OutputStream os = new FileOutputStream(
"C:\\Documents and Settings\\Administrator.DCB5E0D91E0D436\\桌面\\test2.txt");
byte[] bytes1 = new byte[64];
while (is.read(bytes1) > 0) {
byte[] de = encrypt.decrypt(encrypt.privateKey, bytes1);
bytes1 = new byte[64];
os.write(de, 0, de.length);
}
os.close();
is.close();
System.out.println("write success");

} catch (Exception e) {
e.printStackTrace();
}
}

/** */
/**
* * Encrypt String. *
*
* @return byte[]
*/
protected byte[] encrypt(RSAPublicKey publicKey, byte[] obj) {
if (publicKey != null) {
try {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
return cipher.doFinal(obj);
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}

/** */
/**
* * Basic decrypt method *
*
* @return byte[]
*/
protected byte[] decrypt(RSAPrivateKey privateKey, byte[] obj) {
if (privateKey != null) {
try {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return cipher.doFinal(obj);
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}
}

注意，RSAPrivateKey与RSAPublicKey在加密和解密中需保持一致，如果加密与解密需要分开进行，则需要把RSAPrivateKey与RSAPublicKey写入文件或其他方式保存进行解密

加密：
1 ，读取文件 获得 文件的字节数组

2. 将字节数据按照自己指定的算法进行换算，(就是加密过程)

3. 将换算结果 重新生成为新的文件(加密文件)

解密：
1 ，读取文件 获得加密文件的字节数组

2. 将字节数据按照自己指定的算法进行换算，（就是解密过程）

3. 将换算结果 重新生成为新的文件(原文件)

可以用des加密，它是对每八个字符为单位进行加密。网上有很多实现des加密的java源代码，你可以下载一个。 des加密可以设置自己的密钥，只有解密时的密钥与加密时的密钥相同，才会正确解析

文本文档里存的都是字符，所以可以看懂。你用JAVA写个程序，把文档里的字符读出来，然后以二进制形式往里写，这样别人就看不懂了。当然读的时候也要再用程序以二进制形式读进来