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POHow to pass byte arrays between Java and JavaScript
 

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  1. POHow to pass byte arrays between Java and JavaScript
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    <p>I need to access SecureRandom Java Object from Javascript. My ultimate goal is to grab 4 bytes from PRNG and convert it to Javascript integer variable. According to <a href="http://download.oracle.com/javase/1.4.2/docs/api/java/security/SecureRandom.html" rel="noreferrer">http://download.oracle.com/javase/1.4.2/docs/api/java/security/SecureRandom.html</a>, the following two lines of Java code are supposed to do grab 4 random bytes:</p> <pre><code>byte bytes[] = new byte[4]; random.nextBytes(bytes); </code></pre> <p>My problems is that I don't know how to 1) allocate byte array suitable for passing to Java method 2) parse that array into integer afterwards</p> <p>So far I have managed to getSeed() method which returns an array of random bytes. When I render HTML code provided below in Firefox it shows "[B@16f70a4", which appears to be a pointer or something.</p> <pre><code>&lt;script&gt; var sprng = new java.security.SecureRandom(); random = sprng.getSeed(4); document.write(random + "&lt;br/&gt;\n"); &lt;/script&gt; </code></pre> <p>This makes me think that I succeed to instantiate and access Java class, but have a problem with type conversion.</p> <p>Can anyone please help me to write <strong>allocateJavaByteArray(N)</strong> and <strong>convertJavaByteArrayToInt(N)</strong> to let the following code work:</p> <pre><code>var sprng = new java.security.SecureRandom(); var nextBytes = allocateJavaByteArray(4); srng.nextBytes(nextBytes); var nextInt = convertJavaByteArrayToInt(4); </code></pre> <p>Thank you in advance.</p>
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    1. COWhat sort of weird context are you in that you can get at Java runtime from a `<script>` tag? I think there may be some confusion afoot here.
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    2. COI have tested it in Firefox 3.0 on Ubuntu. See also http://docstore.mik.ua/orelly/webprog/jscript/ch22_03.htm
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    3. COfind a good JSON encoding class for java and pass only JSON as any data for javascript. BTW - I don't get how You put java in <script> tags either.
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