JAVA servlets - open message popup
I want to user HttpServletResponse object to compose a response that will tell the browser client to open a popup with some message - how can i开发者_如何学运维 do that?
Every Servlet response is basically an Http doc/snippet. So you could return a call to a javascript function that will be executed on the client side. The function can be passed in that Servlet response or it can be pre-included in the .js file.
just an example:
//servlet code
PrintWriter out = response.getWriter();
response.setContentType("text/html");
out.println("<script type=\"text/javascript\">");
out.println("alert('deadbeef');");
out.println("</script>");
Add to HttpServletResponse some Javascript code that will open a popup, something like
<script type="text/javascript">
function popupWindow() {
window.open( "someLinkToBePoppedUp" )
}
</script>
Basically, you cannot do that directly. You must send in response some code (probably HTML and JS) which will instruct client browser to show message window, eg
String someMessage = "Error !";
PrintWriter out = response.getWriter();
out.print("<html><head>");
out.print("<script type=\"text/javascript\">alert(" + someMessage + ");</script>");
out.print("</head><body></body></html>");
Generally speaking, you can't.
Thanks to their popularity for annoying adverts, most browsers reject attempts to open popups that aren't a response to something the user does within a page.
If you just want to display messaging, you could just include it in a page, or output a script element with an alert statement in it.
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