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copied!<p>There are 2 (actually 3) problems:</p> <p>First, an applet is only allowed to fire HTTP requests on the exact URL base as where the applet is been served from. You can obtain it by <a href="http://download.oracle.com/javase/6/docs/api/java/applet/Applet.html#getCodeBase%28%29" rel="nofollow"><code>Applet#getCodeBase()</code></a> which needs to be used as follows:</p> <pre><code>URL url = new URL(getCodeBase(), "hello?query=select * from airports"); URLConnection connection = url.openConnection(); // ... </code></pre> <p>Second, your query string contains illegal characters for use in URLs (space, asterisk). You need to use <a href="http://download.oracle.com/javase/6/docs/api/java/net/URLEncoder.html#encode%28java.lang.String,%20java.lang.String%29" rel="nofollow"><code>URLEncoder#encode()</code></a> to URL-encode the query string.</p> <pre><code>String query = URLEncoder.encode("select * from airports", "UTF-8"); URL url = new URL(getCodeBase(), "hello?query=" + query); URLConnection connection = url.openConnection(); // ... </code></pre> <p>You also need to ensure that you open the HTML/JSP page with the applet in the browser on the same base URL as where the servlet runs. E.g. <a href="http://localhost:8080/hello/pagewithapplet.html" rel="nofollow">http://localhost:8080/hello/pagewithapplet.html</a> and thus not from commandline or by an appletviewer or something. The applet <em>really</em> needs to be served from the same webserver as where the servlet runs.</p> <hr> <p>Unrelated to the concrete problem as stated in the question, your third problem is that sending a plain SQL statement as request parameter is a <em>very</em> bad idea. What if a hacker decompiles your applet and figures how the applet-servlet communication is done and then modifies the SQL statement into something else, such as <code>delete from airports</code>? </p> <p>Do not do the SQL in the applet, do it in the servlet only and let the applet send specific commands only, such as <code>hello?query=list_airports</code> (which is actually still open for further optimization, think of a REST webservice, but that's left up to you as an exercise).</p>

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