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

public class Md5 {

  public static String getMD5(String val) throws NoSuchAlgorithmException{ 
    MessageDigest md5 = MessageDigest.getInstance("MD5"); 
    md5.update(val.getBytes()); 
    byte[] m = md5.digest();//加密  
    return getString(m); 
  } 
  private static String getString(byte[] b){ 
    StringBuffer buf = new StringBuffer(); 
     for(int i = 0; i < b.length; i ++){ 
      int a = b[i];
      if(a<0)
       a+=256;
      if(a<16)
       buf.append("0");
      buf.append(Integer.toHexString(a));
     
     }   
     return buf.toString(); //32位 
或者 return buf.toString().substring(8,24)；  //16位