A utility for creating a VelocityEngine that's all set up to be used from

within a tool in a sensible manner (loading templates from the classpath,
not logging boatloads of informational messages, not complaining about a
non-existent "macro library").


git-svn-id: https://samskivert.googlecode.com/svn/trunk@1530 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/velocity/VelocityUtil.java

@@ -0,0 +1,57 @@
+//
+// $Id$
+
+package com.samskivert.velocity;
+
+import java.util.Properties;
+
+import org.apache.velocity.VelocityContext;
+import org.apache.velocity.app.VelocityEngine;
+import org.apache.velocity.runtime.RuntimeServices;
+import org.apache.velocity.runtime.log.LogSystem;
+import org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader;
+
+/**
+ * Handy Velocity-related routines.
+ */
+public class VelocityUtil
+{
+    /**
+     * Creates a {@link VelocityEngine} that is configured to load
+     * templates from the classpath and log using the samskivert logging
+     * classes and not complain about a bunch of pointless stuff that it
+     * generally complains about.
+     *
+     * @throws Exception if a problem occurs initializing Velocity. We'd
+     * throw something less generic, but that's what
+     * {@link VelocityEngine#init} throws.
+     */
+    public VelocityEngine createEngine ()
+        throws Exception
+    {
+        // initialize velocity which we'll use for templating
+        Properties props = new Properties();
+        props.put(VelocityEngine.VM_LIBRARY, "");
+        props.put(VelocityEngine.RESOURCE_LOADER, "classpath");
+        props.put("classpath." + VelocityEngine.RESOURCE_LOADER + ".class",
+                  ClasspathResourceLoader.class.getName());
+        VelocityEngine velocity = new VelocityEngine();
+        velocity.init(props);
+        velocity.setProperty(
+            VelocityEngine.RUNTIME_LOG_LOGSYSTEM, _logger);
+        return velocity;
+    }
+
+    /** Handles logging for Velocity. */
+    protected static LogSystem _logger = new LogSystem() {
+        public void init (RuntimeServices rs) {
+            // nothing doing
+        }
+        public void logVelocityMessage (int level, String message) {
+            // skip anything other than warnings or errors
+            if (level == WARN_ID || level == ERROR_ID) {
+                System.err.println(message);
+            }
+        }
+    };
+}