Populating bean attributes from servlet Request

Question

I know that in a JSP, you can use
<jsp:setProperty name="p_filters" property="*"/>To populate the properties of a bean from parameters in a request.
Is there a reliable programmatic way to do this? Since I am using Tomcat, I could use
JspRuntimeLibrary.introspect(p_filters, request);But that relies on the servlet container's internal classes.
There really should be a way of doing this easily in a servlet as well as in a JSP! It should be part of the servlet standard, and the JSP standard <setProperty> tag should use that!

Answer 1

Well, that was buggy. Also, I've added common data types
     private static SimpleDateFormat[] df =
          new SimpleDateFormat("dd-MMM-yy"),
          new SimpleDateFormat("dd-MMM-yyyy"),
          new SimpleDateFormat("yyyyMMdd"),
          new SimpleDateFormat("dd/MM/yy"),
          new SimpleDateFormat("dd/MM/yyyy")
     public static Date parseDate(String d)
          Date result = null;
          for (int i = 0; i < df.length; i++)
               try
                    result = df.parse(d);
                    if (result != null)
                         return result;
               catch (Exception e) // Ignore
          return result;
     Sets all attributes of a bean using available parameters from HTTP request
     attributes without a matching parameter in the request are cleared.
     public static void populateBeanFromRequest(Object bean, HttpServletRequest request)
          Object[]     setParam = new Object[1];
          Method[]     methods = bean.getClass().getMethods();
          String          empty = "";
          Boolean          boolZero = new Boolean(false);
          Byte          bZero = new Byte((byte)0);
          Short          sZero = new Short((short)0);
          Integer          iZero = new Integer(0);
          Long          lZero = new Long(0);
          Float          fZero = new Float(0);
          Double          dZero = new Double(0);
          Date          dateZero = new Date(0);
          for (int i = 0; i < methods.length; i++)
               Class[] paramClass = methods[i].getParameterTypes();
               if (paramClass.length == 1)
                    String methodName = methods[i].getName();
                    if (methodName.substring(0, 3).equals("set"))
                         String propertyName = methodName.substring(3, 4).toLowerCase() + methodName.substring(4);
                         Logger.debug("Found property " + propertyName);
                         String paramValue = request.getParameter(propertyName);
                         if (paramValue == null)
                              Logger.debug("No matching parameter found");
                         else
                              Logger.debug("Found parameter value " + paramValue);
                         try
                              if (paramClass[0] == String.class)
                                   setParam[0] = (paramValue == null) ? empty : paramValue;
                              else if (paramClass[0] == Integer.TYPE)
                                   setParam[0] = (paramValue == null) ? iZero : new Integer(paramValue);
                              else if (paramClass[0] == Date.class)
                                   setParam[0] = (paramValue == null) ? dateZero : parseDate(paramValue);
                              else if (paramClass[0] == Byte.TYPE)
                                   setParam[0] = (paramValue == null) ? bZero : new Byte(paramValue);
                              else if (paramClass[0] == Short.TYPE)
                                   setParam[0] = (paramValue == null) ? sZero : new Short(paramValue);
                              else if (paramClass[0] == Boolean.TYPE)
                                   setParam[0] = (paramValue == null) ? boolZero : new Boolean(paramValue);
                              else if (paramClass[0] == Long.TYPE)
                                   setParam[0] = (paramValue == null) ? lZero : new Long(paramValue);
                              else if (paramClass[0] == Float.TYPE)
                                   setParam[0] = (paramValue == null) ? fZero : new Float(paramValue);
                              else if (paramClass[0] == Double.TYPE)
                                   setParam[0] = (paramValue == null) ? dZero : new Double(paramValue);
                              else
                                   continue;
                              Logger.debug(methodName + "(" +
                                   ((paramClass[0] == String.class) ? "\"" : "") +
                                   setParam[0].toString() +
                                   ((paramClass[0] == String.class) ? "\"" : "") + ")");
                              methods[i].invoke(bean, setParam);
                         catch (Exception e)
                              Logger.error("Error populating bean", e);
                              continue;