java-template

A minimal, easy to use, extreme high performance Template Engine for Java with a minimal footprint

Current Version: See my GitLab

Use Case

With many other templating engines at your hand, why choose this one?

It is way smaller and requires way less configuration (namely none) than, say thymeleaf.
It is intended to be used for very small templates on enormous throughput with just basic put-a-value-here logic (although you may build more complex things with custom placeholder types).
Its syntax is configurable to your hearts content.
Compared to String.replace its (a) blazing fast and (b) more expressive in code.

Features

Blazing fast template processing (around 16k hello world templates per millisecond in my local single-threaded benchmarks)
Builds precompiled templates as a java object structure
Ease to use template language
Configurable template language (if you prefer another syntactic flavor)
A Template is thread safe to process

Examples

You can both use an inlined syntax, giving you adhoc-templating:

Template.process(
    "Hello, $(name, World)!",
    Map.of("name","Tim")
)

Or you may want to build a Template before using it multiple times (which gives you a significant performance boost).

Template helloWorldTemplate=TemplateBuilder.build("I am precompiled but executed at $datetime(time, yyyy-MM-dd, some unknown time)!");
String resultNow=helloWorldTemplate.process(Map.of("time",ZonedDateTime.now()));
// ... take some coffee
String resultLater=helloWorldTemplate.process(Map.of("time",ZonedDateTime.now()));

As you can see, you may provide a default value if some placeholders are left blank. But you can omit that, auto-filling the placeholder with its name. Also the format for times and dates may be specified (falling back to ISO format if omitted).

There are some types of placeholders:

$(myVar, myDefaultValue) giving you just the String value of the variable
$datetime(myVar, myFormat, myDefaultValue) giving you just the formatted value
$enum(myVar, myDefaultValue) giving you the enums name
$myCustomPlaceholderDefinition(whatever content i like) can be implemented by you, see PlaceholderDefinition

For examples on that, see src/example/.../CustomPlaceholderExample

If you like to customize the locale settings, you may choose a slightly more verbose way (showing you lazy evaluation here too).

Context context=new Context(Locale.GERMANY,TimeZone.getTimeZone(ZoneId.of("Europe/Berlin")));
context.put("name","lazy Tim"::toString);
String lazyText=helloWorldTemplate.process(context);

Benchmarks

Some benchmarking results can be found in benchmark.txt and reproduced from src/test/.../SpeedTest using JMH. Here is the key part:

Each test case processes a hello world template (as seen above) 5 million times.
Below are the average times for that:

Benchmark                                  Mode  Cnt  Score   Error  Units
SpeedTest.test_textformat_compiling        avgt    3  2,192 ± 0,158   s/op
SpeedTest.test_textformat_precompiled      avgt    3  0,299 ± 0,053   s/op
SpeedTest.test_thymeleaf                   avgt    3  4,860 ± 0,241   s/op

Installing