本文介绍了在JAVA开发环境中如何对文件和数据进行有效的加密

				DES 加解密的封装和 使用的例子（转）
				
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				DES加密封装 
				
				package org.jtool.desutils; 
				import java.security.SecureRandom; 
				import javax.crypto.*; 
				import javax.crypto.spec.DESKeySpec; 
				public class DESEncrypt { 
				private byte[] desKey; 
				public DESEncrypt(byte[] desKey) { 
				this.desKey = desKey; 
				} 
				public byte[] doEncrypt(byte[] plainText) throws Exception { 
				// DES算法要求有一个可信任的随机数源 
				SecureRandom sr = new SecureRandom(); 
				byte rawKeyData[] = desKey;/* 用某种方法获得密匙数据 */ 
				// 从原始密匙数据创建DESKeySpec对象 
				DESKeySpec dks = new DESKeySpec(rawKeyData); 
				// 创建一个密匙工厂，然后用它把DESKeySpec转换成 
				// 一个SecretKey对象 
				SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES"); 
				SecretKey key = keyFactory.generateSecret(dks); 
				// Cipher对象实际完成加密操作 
				Cipher cipher = Cipher.getInstance("DES"); 
				// 用密匙初始化Cipher对象 
				cipher.init(Cipher.ENCRYPT_MODE, key, sr); 
				// 现在，获取数据并加密 
				byte data[] = plainText;/* 用某种方法获取数据 */ 
				// 正式执行加密操作 
				byte encryptedData[] = cipher.doFinal(data); 
				return encryptedData; 
				} 
				} 
				
				
				DES解密封装 
				
				package org.jtool.desutils; 
				import java.security.SecureRandom; 
				import javax.crypto.*; 
				import javax.crypto.spec.DESKeySpec; 
				public class DESDecrypt { 
				private byte[] desKey; 
				public DESDecrypt(byte[] desKey) { 
				this.desKey = desKey; 
				} 
				public byte[] doDecrypt(byte[] encryptText) throws Exception { 
				// DES算法要求有一个可信任的随机数源 
				SecureRandom sr = new SecureRandom(); 
				byte rawKeyData[] = desKey; /* 用某种方法获取原始密匙数据 */ 
				// 从原始密匙数据创建一个DESKeySpec对象 
				DESKeySpec dks = new DESKeySpec(rawKeyData); 
				// 创建一个密匙工厂，然后用它把DESKeySpec对象转换成 
				// 一个SecretKey对象 
				SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES"); 
				SecretKey key = keyFactory.generateSecret(dks); 
				// Cipher对象实际完成解密操作 
				Cipher cipher = Cipher.getInstance("DES"); 
				// 用密匙初始化Cipher对象 
				cipher.init(Cipher.DECRYPT_MODE, key, sr); 
				// 现在，获取数据并解密 
				byte encryptedData[] = encryptText;/* 获得经过加密的数据 */ 
				// 正式执行解密操作 
				byte decryptedData[] = cipher.doFinal(encryptedData); 
				return decryptedData; 
				} 
				} 
				
				
				DES加解密使用样例 
				
				package org.jtool.desutils; 
				/** 
				* 
				*/ 
				public class DESTest { 
				public static void main(String[] args) throws Exception { 
				String key = "ABCDEFGH"; 
				String value = "AABBCCDDEE"; 
				DESEncrypt desEncrypt = new DESEncrypt(key.getBytes()); 
				byte[] encryptText = desEncrypt.doEncrypt(value.getBytes()); 
				System.out.println("doEncrypt - " + toHexString(encryptText)); 
				System.out.println("doEncrypt - " + new String(encryptText)); 
				DESDecrypt desDecrypt = new DESDecrypt(key.getBytes()); 
				byte[] decryptText = desDecrypt.doDecrypt(encryptText); 
				System.out.println("doDecrypt - " + new String(decryptText)); 
				System.out.println("doDecrypt - " + toHexString(decryptText)); 
				} 
				/** 
				* 16进制显示数据 
				* 
				* @param value 字节数组 
				* @return 
				*/ 
				public static String toHexString(byte[] value) { 
				String newString = ""; 
				for (int i = 0; i < value.length; i++) { 
				byte b = value[i]; 
				String str = Integer.toHexString(b); 
				if (str.length() > 2) { 
				str = str.substring(str.length() - 2); 
				} 
				if (str.length() < 2) { 
				str = "0" + str; 
				} 
				newString += str; 
				} 
				return newString.toUpperCase(); 
				} 
				}