转自：http://blog.csdn.net/YangLian20009/article/details/7252677

package sn.len.demo;  
  
import java.io.UnsupportedEncodingException;  
import java.security.MessageDigest;  
import java.security.NoSuchAlgorithmException;  
/** 
 * 32位MD5加密算法 
 * @author <a href="http://www.xmmobiles.com">Mark</a> 
 * 
 */  
public class MD5  
{  
    public static void main(String[] args)  
    {  
        System.out.println("admin字符串经过32位MD5加密结果为:"+getMD5Str("admin"));  
    }  
  
    private static String getMD5Str(String str)  
    {  
        MessageDigest messageDigest = null;  
        try  
        {  
            messageDigest = MessageDigest.getInstance("MD5");  
            messageDigest.reset();  
            messageDigest.update(str.getBytes("UTF-8"));  
        } catch (NoSuchAlgorithmException e)  
        {  
            System.out.println("NoSuchAlgorithmException caught!");  
            System.exit(-1);  
        } catch (UnsupportedEncodingException e)  
        {  
            e.printStackTrace();  
        }  
  
        byte[] byteArray = messageDigest.digest();  
  
        StringBuffer md5StrBuff = new StringBuffer();  
  
        for (int i = 0; i < byteArray.length; i++)  
        {  
            if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)  
                md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));  
            else  
                md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));  
        }  
        return md5StrBuff.toString();  
    }  
}