public class DefaultKeyGenerator implements KeyGenerator { 
 
  public static final int NO_PARAM_KEY = 0; 
  public static final int NULL_PARAM_KEY = 53; 
 
  public Object generate(Object target, Method method, Object... params) { 
    if (params.length == 1) { 
      return (params[0] == null ? NULL_PARAM_KEY : params[0]); 
    } 
    if (params.length == 0) { 
      return NO_PARAM_KEY; 
    } 
    int hashCode = 17; 
    for (Object object : params) { 
      hashCode = 31 * hashCode + (object == null ? NULL_PARAM_KEY : object.hashCode()); 
    } 
    return Integer.valueOf(hashCode); 
  } 
 
} 

public static void main(String argv[]) 
  { 
    DefaultKeyGenerator g = new DefaultKeyGenerator(); 
    Integer param0 = 1000000759; 
    String param1 = "11"; 
    System.out.println(" param0="+param0+", param1="+param1+" generate key: "+g.generate(null,null,param0,param1)); 
    Integer param01 = 1000000757; 
    String param11 = "31"; 
    System.out.println("param01="+param01+",param11="+param11+" generate key: "+g.generate(null,null,param01,param11)); 
  }