MD5加密

package com.cccp.resume.util;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
/*
 * MD5加密工具类
 */
public class MD5Util {
	public static void Md5(String plainText){
		try { 
				MessageDigest md = MessageDigest.getInstance("MD5"); 
				md.update(plainText.getBytes()); 
				byte b[] = md.digest(); 
				int i;
				StringBuffer buf = new StringBuffer(""); 
				for (int offset = 0; offset < b.length; offset++) { 
				i = b[offset]; 
				if(i<0) i+= 256; 
				if(i<16) 
				buf.append("0"); 
				buf.append(Integer.toHexString(i)); 
				} 
				System.out.println("result: " + buf.toString());//32位的加密 
				System.out.println("result: " + buf.toString().substring(8,24));//16位的加密 
			}
			catch (NoSuchAlgorithmException e) { 
					e.printStackTrace(); 
			} 
		}
		// MD5加码。32位   
	public static String MD5(String inStr) {   
			
		MessageDigest md5 = null;   
		try {   
			md5 = MessageDigest.getInstance("MD5");   
		} 
		catch (Exception e) {   
			System.out.println(e.toString());   
			e.printStackTrace();   
			return "";   
		}   
		char[] charArray = inStr.toCharArray();   
		byte[] byteArray = new byte[charArray.length];   

		for (int i = 0; i < charArray.length; i++)   
			byteArray[i] = (byte) charArray[i];   
		
		byte[] md5Bytes = md5.digest(byteArray);   

		StringBuffer hexValue = new StringBuffer();   

		for (int i = 0; i < md5Bytes.length; i++) {   
			int val = ((int) md5Bytes[i]) & 0xff;   
			if (val < 16)   
			hexValue.append("0");   
			hexValue.append(Integer.toHexString(val));   
			}   
			return hexValue.toString();   
		}   

		// 可逆的加密算法   
		public static String KL(String inStr) {   
		// String s = new String(inStr);   
			char[] a = inStr.toCharArray();   
			for (int i = 0; i < a.length; i++) {   
				a[i] = (char) (a[i] ^ 't');   
			}   
			String s = new String(a);   
			return s;   
		}  

		// 加密后解密   
		public static String JM(String inStr) {   
			char[] a = inStr.toCharArray();   
			for (int i = 0; i < a.length; i++) {   
				a[i] = (char) (a[i] ^ 't');   
			}   
			String k = new String(a);   
			return k;   
		}
		public static void main(String[] args) {
			Md5("123456");
		System.out.println();
		String s = new String("123456");   
		System.out.println("原始：" + s);   
		System.out.println("MD5后：" + MD5(s));   
		System.out.println("MD5后再加密：" + KL(MD5(s)));   
		System.out.println("解密为MD5后的：" + JM(KL(MD5(s))));   
		}
}