Overriding property files in spring

0.) notes.md

Overriding property files in spring

I think the trick is to just use one property place holder and I think this covers all of your scenarios:

It resolves ${full.url} in this way:

• first default.properties gets loaded => full.url=http://prod:9090
• then dev-test.properties overrides the hostname and port name => full.url=http://test:8080
• then development properties overrides the hostname only => full.url=http://localhost:8080

It also doesn't blow up that it can't find "override-I-Dont-Exist.properties" file but if we added it then it could override any property.

It also blows up if we tried to find a property called ${iDontExist}

One PropertyPlaceholderConfigurer can cope with strange property dependency cycles across it's own files, but if you have two, then they can't cope with references to properties in each other's files.

1.) ConfigurationTest.java

package uk.co.optimisticpanda;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations="/applicationContext.xml")
public class ConfigurationTest {

	@Autowired
	private Bean bean;
	
	@Test
	public void checkingOverrides(){
		assertThat(bean.getProperty(), is("http://localhost:8080/service"));
	}
	
	public static class Bean {

		private String property;

		public Bean(String property){
			this.property = property;
		}

		public String getProperty() {
			return property;
		}
	}

}

2.) application.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:c="http://www.springframework.org/schema/c" xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:util="http://www.springframework.org/schema/util"
	xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context-3.2.xsd
            http://www.springframework.org/schema/mvc     http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">

	<context:annotation-config />

	<!--  later files in the list override earlier ones -->
	<context:property-placeholder location="
				classpath:prod.properties,
				classpath:test.properties,
				classpath:dev.properties,
				classpath:override-I-Dont-Exist.properties,
				"
		ignore-resource-not-found="true" ignore-unresolvable="false"/>


	<bean class="uk.co.optimisticpanda.ConfigurationTest.Bean" c:_0="${full.url}" />

</beans>

3.) prod.properties

service.host=prod
service.port=9090
service.hostAndPort=${service.host}:${service.port}
full.url=http://${service.hostAndPort}/service

4.) test.properties

service.port=8080
service.host=test

5.) dev.properties

service.host=localhost

6.) pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.springframework.samples</groupId>
  <artifactId>config-test</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  
  <properties>

		<!-- Generic properties -->
		<java.version>1.6</java.version>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

		<!-- Spring -->
		<spring-framework.version>3.2.3.RELEASE</spring-framework.version>

		<!-- Hibernate / JPA -->
		<hibernate.version>4.2.1.Final</hibernate.version>

		<!-- Logging -->
		<logback.version>1.0.13</logback.version>
		<slf4j.version>1.7.5</slf4j.version>

		<!-- Test -->
		<junit.version>4.11</junit.version>

	</properties>
	
	<dependencies>
		<!-- Spring and Transactions -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${spring-framework.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-tx</artifactId>
			<version>${spring-framework.version}</version>
		</dependency>

		<!-- Logging with SLF4J & LogBack -->
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>${slf4j.version}</version>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-classic</artifactId>
			<version>${logback.version}</version>
			<scope>runtime</scope>
		</dependency>

		<!-- Hibernate -->
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>${hibernate.version}</version>
		</dependency>

		
		<!-- Test Artifacts -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-test</artifactId>
			<version>${spring-framework.version}</version>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>${junit.version}</version>
			<scope>test</scope>
		</dependency>

	</dependencies>	
</project>