java 采用MD5加密解密详解编程语言

package endecrypt;   
   
import java.io.UnsupportedEncodingException;   
import java.security.MessageDigest;   
import java.security.NoSuchAlgorithmException;   
   
/**  
 * 采用MD5加密解密  
 * @author tfq  
 * @datetime 2011-10-13  
 */   
public class MD5Util {   
   
    /***  
     * MD5加码 生成32位md5码  
     */   
    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 执行一次加密，两次解密  
     */    
    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;   
   
    }   
   
    // 测试主函数   
    public static void main(String args[]) {   
        String s = new String("tangfuqiang");   
        System.out.println("原始：" + s);   
        System.out.println("MD5后：" + string2MD5(s));   
        System.out.println("加密的：" + convertMD5(s));   
        System.out.println("解密的：" + convertMD5(convertMD5(s)));   
   
    }   
}