[github-278] Resolve all SpotBugs P1 issues in Main and Test. Thanks to Andreas Reichel. This closes #278

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1895017 13f79535-47bb-0310-9956-ffa450edef68

poi/src/main/java/org/apache/poi/util/RandomSingleton.java

@@ -0,0 +1,19 @@
+package org.apache.poi.util;
+
+import java.security.SecureRandom;
+
+/*
+If it is important that the generated Random numbers not be guessable,
+you MUST NOT create a new Random for each random number; the values are too easily guessable.
+
+You should strongly consider using a java.security.SecureRandom instead
+(and avoid allocating a new SecureRandom for each random number needed).
+*/
+
+public class RandomSingleton {
+    private static final SecureRandom INSTANCE = new SecureRandom();
+
+    public static SecureRandom getInstance() {
+        return INSTANCE;
+    }
+}