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Accessing Spring properties in a non-Spring application. This test demonstrates creating an application context that doesn't create beans but does setup the environment.
package com.example;
import java.util.Arrays;
import java.util.NavigableSet;
import java.util.Set;
import java.util.TreeSet;
import org.junit.Assert;
import org.junit.Test;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.Banner;
import org.springframework.boot.SpringApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.EnumerablePropertySource;
import org.springframework.core.env.Environment;
import org.springframework.core.env.PropertySource;
public class SpringPropertiesTest {
private final static Class<?> APPLICATION_CLASS = SpringPropertiesTest.class;
private final static String[] NO_ARGS = { };
public void testCommandLineProperty() {
int port = 8081;
String[] args = { "--port=" + port };
Environment environment = getEnvironment(APPLICATION_CLASS, args);
// Retrieve property as both string and int.
Assert.assertEquals(Integer.toString(port), environment.getProperty("port"));
Assert.assertEquals(port, environment.getProperty("port", Integer.class).intValue());
public void testStandardKey() {
Environment environment = getEnvironment(APPLICATION_CLASS, NO_ARGS);
public void testGetAllKeys() {
Environment environment = getEnvironment(APPLICATION_CLASS, NO_ARGS);
Set<String> keys = getAllKeys(environment);
public void testSystemProperty() {
Environment environment = getEnvironment(APPLICATION_CLASS, NO_ARGS);
String systemPropertyKey = "java.version";
// Test that system properties are available via Spring environment.
Assert.assertEquals(System.getProperty(systemPropertyKey), environment.getProperty(systemPropertyKey));
private static Environment getEnvironment(Object source, String[] args) {
SpringApplication springApplication = new BeanlessSpringApplication(source);
ApplicationContext context =;
return context.getEnvironment();
private static NavigableSet<String> getAllKeys(Environment environment) {
NavigableSet<String> allKeys = new TreeSet<>();
for (PropertySource<?> propertySource : ((ConfigurableEnvironment)environment).getPropertySources()) {
if (propertySource instanceof EnumerablePropertySource) {
String[] keys = ((EnumerablePropertySource<?>)propertySource).getPropertyNames();
return allKeys;
// Normal usage of BeanlessSpringApplication would be:
// SpringApplication springApplication = new BeanlessSpringApplication(Application.class);
// ApplicationContext context =;
// Where "Application.class" is our main class and "args" are the arguments passed to its main method.
/** A SpringApplication subclass that does not create beans (the most expensive part of application startup). */
public static class BeanlessSpringApplication extends SpringApplication {
public BeanlessSpringApplication(Object... sources) {
protected void refresh(ApplicationContext applicationContext) {
// Do nothing.
protected void afterRefresh(ConfigurableApplicationContext context, ApplicationArguments args) {
// Do nothing.
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