MD5加密（Android里和Java SE里是一样的）

package com.gnnuit.mobilesafe.util;

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

public class MD5Encoder {
    /**
     * MD5加密
     * 
     * @param pwd要加密的数据
     * @return 加密后的数据
     * @throws Exception
     */
    public static String encode(String pwd) {
        try {
            MessageDigest digest = MessageDigest.getInstance("MD5");
            byte[] bytes = digest.digest(pwd.getBytes());
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < bytes.length; i++) {
                String s = Integer.toHexString(0xff & bytes[i]);
                if (s.length() == 1) {
                    sb.append("0" + s);
                } else {
                    sb.append(s);
                }
            }
            return sb.toString();
        } catch (NoSuchAlgorithmException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw new RuntimeException("永远不会发生");
        }
    }
}