MD5加密

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5 {
	/**
	 * MD5加密类
	 * @param str 要加密的字符串
	 * @return    加密后的字符串
	 */
	public static String toMD5(String str){
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(str.getBytes());
			byte[]byteDigest = md.digest();
			int i;
			StringBuffer buf = new StringBuffer("");
			for (int offset = 0; offset < byteDigest.length; offset++) {
				i = byteDigest[offset];
				if (i < 0)
					i += 256;
				if (i < 16)
					buf.append("0");
				buf.append(Integer.toHexString(i));
			}
			return buf.toString();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			return null;
		}
	}
	
	public static void main(String[] args) {
		System.out.println(new MD5().toMD5("123456"));
//		System.out.println(Integer.MAX_VALUE);
	}
	
}