In this section you will learn how to load Mustache templates from the file system, classpath, web context and more.

The template loader

public interface TemplateLoader {

  String DEFAULT_PREFIX = "/";

  String DEFAULT_SUFFIX = ".hbs";

  String getPrefix();

  String getSuffix();

  TemplateSource sourceAt(final String location) throws IOException;

  String resolve(final String location);
}

Prefix and Suffix

• prefix: gets prepended to template names before being resolved.
• suffix: gets appended to template names before being resolved. Default is: .hbs

Template template = handlebars.compile("hello");

{{> hello}}

You don't need to addprefix(like a home directory) andsuffix(like a file extension), theTemplateLoaderdoes it for you.

The default value ofprefixdepends on a specific implementation ofTemplateLoader.

The default value ofsuffixis .hbs, but as you saw before, you can change to.htmlor whatever make more sense to you (null included).

The template source

public interface TemplateSource {
  String content() throws IOException;

  Reader reader() throws IOException;

  String filename();

  long lastModified();
}

You don't have to implement any of these classes, Handlebars.java does it for you. But if you want to store your templates in a database (for example), these are the two classes you need to implement.

The classpath template loader

The ClassPathTemplateLoader is the default template loader in Handlebars.java. If you don't set a template loader, Handlebars.java assume your templates are in the classpath.

For example:

Handlebars handlebars = new Handlebars();
handlebars.compile("hello"); // resolved to: /hello.hbs

TemplateLoader loader = new ClassPathTemplateLoader("/", ".html");
Handlebars handlebars = new Handlebars(loader);
handlebars.compile("hello"); // resolved to: /hello.html

TemplateLoader loader = new ClassPathTemplateLoader("/templates", ".html");
Handlebars handlebars = new Handlebars(loader);
handlebars.compile("hello"); // resolved to: /templates/hello.html

The file template loader

The FileTemplateLoader load templates from a file system location. This template loader is useful if you need to make change to your templates after a deploy.

For example:

TemplateLoader loader = new FileTemplateLoader("/usr/share/templates",
  ".html");
Handlebars handlebars = new Handlebars(loader);
handlebars.compile("hello"); // resolved to: /usr/share/templates/hello.html

The servlet context template loader

The ServletContextTemplateLoader load templates from a JavaEE Web Context.

For example:

ServletContext servletContext = ...;
TemplateLoader loader = new ServletContextTemplateLoader(servletContext);
Handlebars handlebars = new Handlebars(loader);
handlebars.compile("hello"); // resolved to: /hello.hbs

ServletContext servletContext = ...;
TemplateLoader loader = new ServletContextTemplateLoader(servletContext, "/",
  ".html");
Handlebars handlebars = new Handlebars(loader);
handlebars.compile("hello"); // resolved to: /hello.html

ServletContext servletContext = ...;
TemplateLoader loader = new ServletContextTemplateLoader(servletContext,
  "/WEB-INF/pages", ".html");
Handlebars handlebars = new Handlebars(loader);
handlebars.compile("hello"); // resolved to: /WEB-INF/pages/hello.html

The composite template loader

The CompositeTemplateLoader let you combine two or more template loaders and makes possible multiples templates location for your application.

For example:

ClassPathTemplateLoader cploader = ...;
FileTemplateLoader fsloader = ...;
Handlebars handlebars = new Handlebars().with(cploader, fsloader);
handlebars.compile("hello");

Loaders are executed in the order they are provided, so the first TemplateLoader that is able to resolved a template win.

Conclusion

TheTemplateLoaderandTemplateSourceare two key abstractions in Handlebars.java, they both work together for simplify the storage and resolution of templates.

Want to contribute?

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