java md5

import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;public class md5 { public String str; public void md5s(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)); } str = buf.toString(); 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) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void main(String agrs[]) { md5 md51 = new md5(); md51.md5s("4");//加密4 }}