java-如何打印请求对象的属性和值？

Question

I have a request object that probably belons to this class: https://tomcat.apache.org/tomcat-6.0-doc/api/org/apache/catalina/connector/RequestFacade.html

I am trying to print the names of the attributes and their values. This is my futile attempt.

Enumeration rns = request.getAttributeNames();

while (rns.hasMoreElements()) {
    Object param = rns.nextElement();
    out.println("\nattribute name: " + param.toString());
    out.println("attribute value: " + request.getAttribute(param.toString()));
}

What I am missing? In another language there is a trivial answer to such question. How different it is done in java? Rails: How do I print the request parameters?

my hardcoded attempt

   Enumeration rns = request.getAttributeNames();
    while (rns.hasMoreElements()) {
        out.println("\nattribute name: " + rns.nextElement() );
    }
    // i have copied the logs output from above and edited it to create the array below
    String[] madAttrs = { "dayToGraph",
                          "yearFromGraph",
                          "yaxis",
                          "yearToGraph",
                          "monthToGraph",
                          "monthFromGraph",
                          "currentMachine",
                          "onlyGraph",
                          "currentSample",
                          "currentAnalyte",
                          "dayFromGraph",
                          "analyteid"};
    // then I got what I want.
    for (String an : madAttrs) {
        out.println("sttribute " + an);
        out.println("the value is: "+ request.getAttribute(an));
    }

But how do I do it without hardcoding the attributes in the array?

Answer 1

Not the answer you want, but the real answer to your question

Leave the 1990s in the past and stop putting java code in JSP files.

Instead receive the message in a servlet (or Spring handler) and do java work therein. Next create the display values and put them in some context (perhaps the response) and dispatch the request to your JSP page.

Don't do this

If you refuse to do the above, import the required classes into your JSP file. I will not include the syntax for importing files into a JSP file, but be assured, Google has fewer compunctions about such things than do I.