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

Please refer to my GitLab. This repository was migrated there and is discontinued here.