Loading velocity template inside a jar file

Question

I have a project where I want to load a velocity template to complete it with parameters. The whole application is packaged as a jar file. What I initially thought of doing was this:

VelocityEngine ve = new VelocityEngine();     URL url = this.getClass().getResource("/templates/");     File file = new File(url.getFile());     ve = new VelocityEngine();    ve.setProperty(RuntimeConstants.RESOURCE_LOADER, "file");    ve.setProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH, file.getAbsolutePath());    ve.setProperty(RuntimeConstants.FILE_RESOURCE_LOADER_CACHE, "true");     ve.init();     VelocityContext context = new VelocityContext();     if (properties != null) {     stringfyNulls(properties);     for (Map.Entry<String, Object> property : properties.entrySet()) {      context.put(property.getKey(), property.getValue());     }    }     final String templatePath = templateName + ".vm";    Template template = ve.getTemplate(templatePath, "UTF-8");    String outFileName = File.createTempFile("report", ".html").getAbsolutePath();    BufferedWriter writer = new BufferedWriter(new FileWriter(new File(outFileName)));     template.merge(context, writer);     writer.flush();    writer.close(); 

And this works fine when I run it in eclipse. However, once I package the program and try to run it using the command line I get an error because the file could not be found.

I imagine the problem is in this line:

ve.setProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH, file.getAbsolutePath()); 

Because in a jar the absolute file does not exist, since it's inside a zip, but I couldn't yet find a better way to do it.

Anyone has any ideas?

Answer 1

If you want to use resources from classpath, you should use resource loader for classpath:

ve.setProperty(RuntimeConstants.RESOURCE_LOADER, "classpath");  ve.setProperty("classpath.resource.loader.class", ClasspathResourceLoader.class.getName()); 

Answer 2

Final code, developed using the ideas presented in both answers above:

VelocityEngine ve = new VelocityEngine(); ve.setProperty(RuntimeConstants.RESOURCE_LOADER, "classpath"); ve.setProperty("classpath.resource.loader.class", ClasspathResourceLoader.class.getName());  ve.init();  final String templatePath = "templates/" + templateName + ".vm"; InputStream input = this.getClass().getClassLoader().getResourceAsStream(templatePath); if (input == null) {     throw new IOException("Template file doesn't exist"); }  InputStreamReader reader = new InputStreamReader(input);  VelocityContext context = new VelocityContext();  if (properties != null) {     stringfyNulls(properties);     for (Map.Entry<String, Object> property : properties.entrySet()) {         context.put(property.getKey(), property.getValue());     } }  Template template = ve.getTemplate(templatePath, "UTF-8"); String outFileName = File.createTempFile("report", ".html").getAbsolutePath(); BufferedWriter writer = new BufferedWriter(new FileWriter(new File(outFileName)));  if (!ve.evaluate(context, writer, templatePath, reader)) {     throw new Exception("Failed to convert the template into html."); }  template.merge(context, writer);  writer.flush(); writer.close();