java的MD5加密、解密

import java.security.*;
import java.security.spec.*;
class MD5_test {
publicfinalstatic String MD5(String s) {
char hexDigits[] = {'0', '1','2', '3','4', '5','6', '7','8', '9',
'a', 'b', 'c','d', 'e','f' };
try {
byte[] strTemp = s.getBytes();
MessageDigest mdTemp = MessageDigest.getInstance("MD5");
mdTemp.update(strTemp);
byte[] md = mdTemp.digest();
int j = md.length;
char str[] =newchar[j *2];
int k =0;
for (int i =0; i < j; i++) {
byte byte0 = md[i];
str[k++] = hexDigits[byte0 >>> 4 &0xf];
str[k++] = hexDigits[byte0 & 0xf];
}
returnnew String(str);
} catch (Exception e) {
returnnull;
}
}
publicstaticvoid main(String[] args) {
// MD5_Test aa = new MD5_Test();
System.out.print(MD5_test.MD5("b"));
}
}

加密，解密

import java.security.MessageDigest;
publicclass MD5andKL {

// MD5加碼。32位 publicstatic 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 =newbyte[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 publicstatic 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;} // 加密後解密 publicstatic 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;} // 測試主函數 publicstaticvoid main(String args[]) {String s = new String("a");System.out.println("原始：" + s);System.out.println("MD5後：" + MD5(s));System.out.println("MD5後再加密：" + KL(MD5(s)));System.out.println("解密爲MD5後的：" + JM(KL(MD5(s))));} }

package endecrypt;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 採用MD5加密解密
 * @author tfq
 * @datetime 2011-10-13
 */
public class MD5Util {

	/***
	 * MD5加碼 生成32位md5碼
	 */
	public static String string2MD5(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();

	}

	/**
	 * 加密解密算法 執行一次加密，兩次解密
	 */ 
	public static String convertMD5(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;

	}

	// 測試主函數
	public static void main(String args[]) {
		String s = new String("tangfuqiang");
		System.out.println("原始：" + s);
		System.out.println("MD5後：" + string2MD5(s));
		System.out.println("加密的：" + convertMD5(s));
		System.out.println("解密的：" + convertMD5(convertMD5(s)));

	}
}

http://blog.163.com/leijiangjiahe@126/blog/static/1215467920102511550518/

http://blog.csdn.net/xiangsuixinsheng/article/details/6871868

http://blog.sina.com.cn/s/blog_543e73a80100cpli.html

http://justsee.iteye.com/blog/747824

http://www.eoeandroid.com/thread-81425-1-1.html