Christian's suggestion below is the *best* way to do this. However very
occasionally it won't work, due perhaps to an evil proxy server. In this
case a hack is possible, when setting location.href append a bogus and
random parameter on the end of the url to defeat the proxies page
recognition, forcing it to allow you to fetch a new page.
> -----Original Message-----
> From: Christian Bollmeyer (GMX) [SMTP:[EMAIL PROTECTED]]
> Sent: 09 January 2003 10:34
> To: [EMAIL PROTECTED]
> Subject: Re: Location.href
>
> Am Donnerstag, 9. Januar 2003 16:36 schrieb KEITH KOSMICKI:
>
> > I have a button on a page that uses location.href to go to other pages.
> > One of these buttons options goes to the previous page.
> > However, it loads the page out of history rather than loading a new page
> > from the server.url Replace does not work and gives syntax error and
> other
> > options so far load a blank page. Any suggestions.
>
> Obviously, the previous page was cached. For dynamic pages that should
> be requested again each time, you have to tell the browser | proxy that it
> shouldn't use the cache. Unfortunately, the mechanism is not standardized,
> but putting the following lines in your JSP page somewhere before
> sending body content should normally suffice:
>
> <%
> response.addHeader("Pragma", "no-cache");
> response.setHeader("Cache-control", "no-cache");
> response.setDateHeader("Expires", 0);
> %>
>
> There is a fourth possible line which I saw once but don't remember
> right now, but that's kind of esoteric anyway. As this is a common task,
> you can also write a handy little tag for such stuff, as described in
> O'Reilly's JSP book, for example (www.TheJSPBook.com). If the
> page in question is static HTML, those lines should go into <META>
> tags in the <HEAD> section of your page.
>
> HTH,
>
> -- Chris (SCPJ2)
>
> OK, I'll also add the code for my own solution. Most parts are
> generated by Sun ONE Studio, as I was lazy and used the
> wizard, so the code is kind of verbose. But still. Here it comes:
>
> package de.christianbollmeyer.tags;
>
> import javax.servlet.jsp.tagext.TagSupport;
> import javax.servlet.jsp.JspException;
> import javax.servlet.jsp.PageContext;
> import javax.servlet.ServletRequest;
> import javax.servlet.http.HttpServletResponse;
> import javax.servlet.jsp.tagext.BodyTagSupport;
> import javax.servlet.jsp.tagext.BodyContent;
> import javax.servlet.jsp.JspWriter;
> import java.io.PrintWriter;
> import java.io.IOException;
> import javax.servlet.jsp.tagext.Tag;
> import javax.servlet.jsp.tagext.IterationTag;
> import javax.servlet.jsp.tagext.BodyTag;
>
> public class NoCacheTag extends TagSupport {
>
> public NoCacheTag() {
> super();
> }
>
> // doStartTag()
> public void otherDoStartTagOperations() {}
> public boolean theBodyShouldBeEvaluated() {
> return false;
> }
>
> // doEndTag()
> public void otherDoEndTagOperations() {
> HttpServletResponse rsp
> = (HttpServletResponse)(Object) pageContext.getResponse();
> rsp.addHeader("Pragma", "No-cache");
> rsp.addHeader("Cache-Control", "no-cache");
> rsp.addDateHeader("Expires", 0L);
> }
>
> public boolean shouldEvaluateRestOfPageAfterEndTag() {
> return true;
> }
>
> // doAfterBody()
> public boolean theBodyShouldBeEvaluatedAgain() {
> return false;
> }
>
> /** .//GEN-BEGIN:doStartTag
> *
> * This method is called when the JSP engine encounters the start tag,
> * after the attributes are processed.
> * Scripting variables (if any) have their values set here.
> * @return EVAL_BODY_INCLUDE if the JSP engine should evaluate the tag
> body, otherwise return SKIP_BODY.
> * This method is automatically generated. Do not modify this method.
> * Instead, modify the methods that this method calls.
> *
> */
> public int doStartTag() throws JspException, JspException {
> otherDoStartTagOperations();
>
> if (theBodyShouldBeEvaluated()) {
> return EVAL_BODY_INCLUDE;
> } else {
> return SKIP_BODY;
> }
> }//GEN-END:doStartTag
>
> /** .//GEN-BEGIN:doEndTag
> *
> *
> * This method is called after the JSP engine finished processing the
> tag.
> * @return EVAL_PAGE if the JSP engine should continue evaluating the
> JSP
> page, otherwise return SKIP_PAGE.
> * This method is automatically generated. Do not modify this method.
> * Instead, modify the methods that this method calls.
> *
> */
> public int doEndTag() throws JspException, JspException {
> otherDoEndTagOperations();
>
> if (shouldEvaluateRestOfPageAfterEndTag()) {
> return EVAL_PAGE;
> } else {
> return SKIP_PAGE;
> }
> }//GEN-END:doEndTag
> }
>
> > Best,
> >
> >
> > Keith E. Kosmicki
> > Applications Consultant
> > State of IL Human Services
> > STL Technology Partners
> >
> >
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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> >
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> > http://java.sun.com/products/jsp/faq.html
> > http://www.esperanto.org.nz/jsp/jspfaq.jsp
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> > http://www.jspinsider.com
>
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