hocon-spring

NOTE: hocon-spring has been moved to AVSystem commons library

An implementation of BeanDefinitionReader that is able to parse HOCON (Typesafe Config) files.

This effectively allows you to define your Spring application context entirely in HOCON, which gives you following advantages over XML:

• easy customization and overriding thanks to HOCON merging features
• overall much easier reuse of configuration fragments
• cleaner, more concise syntax

Example:

beans {
  someAbstractBean {
    %abstract = true

    settings {
      inherited = 32
    }
    characters.%set = [a, g, o]
  }

  someBean {
    %class = com.example.SomeBeanClass
    %parent = someAbstractBean

    someNumberProperty = 42
    someStringProperty = someStringValue
    settings {
      %merge = true
      someSetting = 5
      anotherSetting = 20
    }
    numbers = [1, 2, 3, 4, 5]
    characters {
      %merge = true
      %set = [a, b, c, d]
    }
    nestedBean {
      %class = com.example.SomeOtherBeanClass

      otherNestedBean.%ref = otherBean
    }
  }

  otherBean {
    %class = com.example.YetAnotherBeanClass

    someRandomProperty = someRandomString
  }
}

An equivalent XML would be:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

  <bean id="someAbstractBean" abstract="true">
    <property name="settings">
      <map>
        <entry key="inherited" value="32"/>
      </map>
    </property>

    <property name="characters">
      <set>
        <value>a</value>
        <value>g</value>
        <value>o</value>
      </set>
    </property>
  </bean>

  <bean id="someBean" class="com.example.SomeBeanClass" parent="someAbstractBaen">
    <property name="someNumberProperty" value="42"/>
    <property name="someStringProperty" value="someStringValue"/>

    <property name="settings">
      <map merge="true">
        <entry key="someSetting" value="5"/>
        <entry key="anotherSetting" value="20"/>
      </map>
    </property>

    <property name="numbers">
      <list>
        <value>1</value>
        <value>2</value>
        <value>3</value>
        <value>4</value>
        <value>5</value>
      </list>
    </property>

    <property name="characters">
      <set merge="true">
        <value>a</value>
        <value>b</value>
        <value>c</value>
        <value>d</value>
      </set>
    </property>

    <property name="nestedBean">
      <bean class="com.example.SomeOtherBeanClass">
        <property name="otherNestedBean" ref="otherBean"/>
      </bean>
    </property>

  </bean>

  <bean id="otherBean" class="com.example.YetAnotherBeanClass">
    <property name="someRandomProperty" value="someRandomString"/>
  </bean>

</beans>

How to create application context from HOCON files in Java:

GenericApplicationContext ctx = new GenericApplicationContext();
HoconBeanDefinitionReader bdr = new HoconBeanDefinitionReader(ctx);
bdr.loadBeanDefinitions("/beans.conf");
ctx.refresh();