fluent-generator

fluent-generator allows defining and configuring generators for java beans and entities.

Import

In order to import fluent-generator into your project you have to setup JitPack repositories. Then if you use maven you can add following to your pom.xml file

<dependency>
    <groupId>com.github.pawelkorus</groupId>
    <artifactId>fluent-generator-lib</artifactId>
    <version>master-SNAPSHOT</version>
</dependency>

or if you use gradle

dependencies {
    compile 'com.github.pawelkorus:fluent-generator:master-SNAPSHOT'
}

Usage

Let's assume that following bean class was defined:

@Data
class Shape {
  String id;
  String type;
  int size;
}

For classes like Shape fluent generator may be defined in following way:

interface ShapeGenerator extends Generator<Shape> {
  ShapeGenerator id(Supplier<String> v);
  ShapeGenerator type(Supplier<String> v);
  ShapeGenerator size(Supplier<Integer>);
  ShapeGenerator size(int age);
  Shape build();
}

The simplest way to create instance of ShapeGenerator is to use GeneratorFactory in the following way:

GeneratorFactory generatorFactory = new ReflectGeneratorProxyFactory();
ShapeGenerator generator = generatorFactory.generatorInstance(ShapeGenerator.class);

Next, ShapeGenerator instance may be configured so that it is able to create desired beans. For instance it may be configured so that every Shape instance has id, type and size fields set to some constant values:

generator.id(() -> return "shape1").type(() -> return "Rect").size(5);

Eventually, call to method build will produce new instance of Shape class with fields filled in:

Shape rect1 = generator.build();

Next we may imagine that we need 100 instances of Shape class and all of those instance should have following properties: id set to random UUID, type set to one of two values "Rect" and "Square" and size choosen randomly. To meet this requirements ShapeGenerator instance needs to be configured as follows:

generator
    .id(() -> return UUID.randomUUID())
    .type(oneOf(Arrays.asList("Rect", "Square")))
    .size(randomInt(4, 10));

In this configuration oneOf and randomInt methods come from fluent-generator-supplier module. For more details see Built-in suppliers.

Because of the fact that ShapeGenerator class implementes indirectly Supplier interface it nicely works with Java 8 streams:

Stream.generate(generator).limit(100).collect(Collectors.toList())

Built-in suppliers

Sample repository

For sample repository see fluent-generator-sample