Java

Overview

The Java Generator produces java class files from a linkml model, with optional support for user-supplied jinja2 templates to generate classes with alternate annotations or additional documentation.

Docs

Command Line

gen-java

Generate java classes to represent a LinkML model

gen-java [OPTIONS] YAMLFILE

Options

-V, --version

Show the version and exit.

--true-enums, --no-true-enums

Treat enums as distinct types rather than strings

--visitor <visitor>

Generate a visitor interface for the specified class

--extra-template <extra_template>

Name of an additional, arbitrary template to use

--generate-records, --no-generate-records

Optional Java 17 record implementation (deprecated, use –template-variant=records instead)

--template-file <template_file>

Optional jinja2 template to use for class generation (takes precedence over –template-dir)

--template-variant <template_variant>

Use the specified template variant

--template-dir <template_dir>

Directory containing the Jinja2 templates to use

--package <package>

Package name where relevant for generated class files

--output-directory <output_directory>

Output directory for individually generated class files

Default:

'output'

-f, --format <format>

Output format

Default:

'java'

Options:

java

--metadata, --no-metadata

Include metadata in output

Default:

True

--useuris, --metauris

Use class and slot URIs over model uris

Default:

True

-im, --importmap <importmap>

Import mapping file

--log_level <log_level>

Logging level

Default:

'WARNING'

Options:

CRITICAL | ERROR | WARNING | INFO | DEBUG

-v, --verbose

Verbosity. Takes precedence over –log_level.

--mergeimports, --no-mergeimports

Merge imports into source file (default=mergeimports)

--stacktrace, --no-stacktrace

Print a stack trace when an error occurs

Default:

False

Arguments

YAMLFILE

Required argument

Code

class linkml.generators.javagen.JavaGenerator(schema: str | ~typing.TextIO | ~linkml_runtime.linkml_model.meta.SchemaDefinition | Generator | ~pathlib.Path, schemaview: ~linkml_runtime.utils.schemaview.SchemaView = None, format: str | None = None, metadata: bool = True, useuris: bool | None = None, log_level: int | None = 30, mergeimports: bool | None = True, source_file_date: str | None = None, source_file_size: int | None = None, logger: ~logging.Logger | None = None, verbose: bool | None = None, output: str | None = None, namespaces: ~linkml_runtime.utils.namespaces.Namespaces | None = None, directory_output: bool = False, base_dir: str = None, metamodel_name_map: dict[str, str] = None, importmap: str | ~collections.abc.Mapping[str, str] | None = None, emit_prefixes: set[str] = <factory>, metamodel: ~linkml.utils.schemaloader.SchemaLoader = None, stacktrace: bool = False, include: str | ~pathlib.Path | ~linkml_runtime.linkml_model.meta.SchemaDefinition | None = None, template_file: str | None = None, true_enums: bool = False, package: str = 'example', template_dir: ~pathlib.Path | None = None, template_cache: ~linkml.generators.javagen.TemplateCache = <factory>, gen_classvars: bool = True, gen_slots: bool = True, genmeta: bool = False)[source]

Generates java code from a LinkML schema.

This generators supports an arbitrary number of different styles through the use of “template variants“.

Currently, two variants are available:

  • the default variant represents LinkML classes as Java classes carrying Lombok annotations (https://projectlombok.org);

  • the records variant represents LinkML classes as Java 16 records.

serialize(directory: str, template_variant: str | None = None, extra_templates: list[str] | None = None, visitors: list[str] | None = None, **kwargs) → None[source]

Generate and write the Java code to files.

Parameters:

  • directory – The directory where to write the code files.

  • template_variant – The name of the template variant to use, if any.

  • extra_templates – A list of additional templates from which to generate additional code files. For example, if set to [Foo,Bar], this will generate two additional files Foo.java and Bar.java (assuming the template directory contains the required templates Foo.jinja2 and Bar.jinja2). Users can exploit such additional files to generate any code they might need in addition to the code generated for each class and each enum in the model.

  • visitors – A list of class names for which to generate a visitor interface. For example, if set to [Foo], this will generate a IFooVisitor interface, and the generated code for both the Foo class and all its descendants will include a accept(IFooVisitor) method.

Additional Notes

The Java generator’s default template uses Project Lombok’s @Data annotation, which provides getters, setters, equals and hashcode functionality.

Alternate Template Example

Here is an alternate template using Hibernate JPA annotations, named example_template.java.jinja2

package {{ doc.package }};

import java.util.List;
import lombok.*;
import javax.persistence.*;
import org.hibernate.search.engine.backend.types.*;
import org.hibernate.envers.Audited;
import org.hibernate.search.mapper.pojo.mapping.definition.annotation.*;


@Audited
@Indexed
@Entity
@Data @EqualsAndHashCode(onlyExplicitlyIncluded = true, callSuper = true)
public class {{ cls.name }} {% if cls.is_a -%} extends {{ cls.is_a }} {%- endif %} {
{% for f in cls.fields %}
  private {{f.range}} {{ f.name }};
{%- endfor %}

}

The alternate template for the generator can be specified with the –template_file option

gen-java --package org.biolink.model --output-directory org/biolink/model \
         --template_file example_template.java.jinja2 biolink-model.yaml