MD5/SHA加密：

import java.io.FileNotFoundException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;public class Test {public static void main(String[] args) throws FileNotFoundException {try {MessageDigest md5Instance = MessageDigest.getInstance("md5");byte[] secretBytes1 = md5Instance.digest("tom".getBytes());String md5Code = new BigInteger(1,secretBytes1).toString(16);for(int i=0;i<32-md5Code.length();i++){md5Code = "0" + md5Code;}System.out.println(md5Code);// 34b7da764b21d298ef307d04d8152dc5String a = "asdvf";System.out.println(new BigInteger(1,a.getBytes()).toString());//System.out.println(new BigInteger(1,a.getBytes()).toString(2));byte[] byteArray = new BigInteger("418547791462").toByteArray();for (int i = 0; i < byteArray.length; i++) {System.out.print((char)byteArray[i]);}// 418547791462MessageDigest shaInstance = MessageDigest.getInstance("sha");byte[] secretBytes2 = shaInstance.digest("jerry".getBytes());String shaCode = new BigInteger(1,secretBytes2).toString(16);for(int i=0;i<40-shaCode.length();i++){shaCode = "0" + shaCode;}System.out.println(shaCode);// asdvf75926e095b28dd773adde5bade93e4836b1d92fc} catch (NoSuchAlgorithmException e) {e.printStackTrace();}}
}

进制转换：

String a = "1234";
int aa = Integer.valueOf(a);
String hexRes = Integer.toString(aa, 16);
System.out.println(hexRes);