org.eclipse.microprofile.config.package-info Maven / Gradle / Ivy
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* Licensed under the Apache License, Version 2.0 (the "License");
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/**
* Configuration for Java Microprofile
*
*
Rational
*
* For many project artifacts (e.g. WAR, EAR) it should be possible to build them only once
* and then install them at different customers, stages, etc.
* They need to target those different execution environments without the necessity of any repackaging.
* In other words: depending on the situation they need different configuration.
*
*
This is easily achievable by having a set of default configuration values inside the project artifact.
* But be able to overwrite those default values from external.
*
*
How it works
*
* A 'Configuration' consists of the information collected from the registered
* {@link org.eclipse.microprofile.config.spi.ConfigSource ConfigSources}.
* These {@code ConfigSources} get sorted according to their ordinal.
* That way it is possible to overwrite configuration with lower importance from outside.
*
*
By default there are 3 ConfigSources:
*
*
* - {@code System.getenv()} (ordinal=400)
* - {@code System.getProperties()} (ordinal=300)
* - all {@code META-INF/microprofile-config.properties} files on the ClassPath.
* (ordinal=100, separately configurable via a config_ordinal property inside each file)
*
*
* That means that one can put the default configuration in a {@code META-INF/microprofile-config.properties} anywhere on the classpath.
* and the Operations team can later simply e.g set a system property to change this default configuration.
*
*
It is of course also possible to register own {@link org.eclipse.microprofile.config.spi.ConfigSource ConfigSources}.
* A {@code ConfigSource} could e.g. read configuration values from a database table, a remote server, etc
*
*
Accessing and Using the Configuration
*
* The configuration of an application is represented by an instance of {@link org.eclipse.microprofile.config.Config}.
* The {@link org.eclipse.microprofile.config.Config} can be accessed via the {@link org.eclipse.microprofile.config.ConfigProvider}.
*
*
* Config config = ConfigProvider#getConfig();
* String restUrl = config.getValue("myproject.some.endpoint.url", String.class);
*
*
* Of course we also support injection via a JSR-330 DI container:
*
* @Inject
* @ConfigProperty(name="myproject.some.endpoint.url");
* private String restUrl;
*
*
* @author Emily Jiang
* @author Mark Struberg
*
*/
@org.osgi.annotation.versioning.Version("1.0")
package org.eclipse.microprofile.config;