Java Expression Language Usage

ExpressionContext.java

public class ExpressionContext {
	private Map<String, Object> context = new HashMap<>();

	public Object get(String key) {
		return context.get(key);
	}

	public void add(String key, Object obj) {
		context.put(key, obj);
	}

	public SimpleContext toELContext(ExpressionFactory factory) {
		SimpleContext result = new SimpleContext();
		for (Map.Entry<String, Object> entry : context.entrySet()) {
			result.setVariable(entry.getKey(), factory.createValueExpression(entry.getValue(), entry.getValue().getClass()));
		}

		return result;
	}
}

ExpressionResolver.java

public class ExpressionResolver {
	public String resolve(String expression, ExpressionContext context) {
		return resolve(expression, context, String.class);
	}

	@SuppressWarnings("unchecked")
	public <T> T resolve(String expression, ExpressionContext context, Class<T> clazz) {
		ExpressionFactory factory = new ExpressionFactoryImpl();
		SimpleContext elContext = context.toELContext(factory);
		ValueExpression val = factory.createValueExpression(elContext, expression, clazz);

		return (T) val.getValue(elContext);
	}
}

ExpressionResolverTest

public class ExpressionResolverTest {
	@Test
	public void noExpressionInString() {
		String input = "input1";
		ExpressionResolver resolver = new ExpressionResolver();
		ExpressionContext context = new ExpressionContext();
		context.add("input1", "bl");

		String resolved = resolver.resolve(input, context);

		Assert.assertEquals("input1", resolved);
	}

	@Test
	public void wholeStringIsExpression() {
		String input = "${input1.concat('a')}";
		ExpressionResolver resolver = new ExpressionResolver();
		ExpressionContext context = new ExpressionContext();
		context.add("input1", "bl");

		String resolved = resolver.resolve(input, context);

		Assert.assertEquals("bla", resolved);
	}

	@Test
	public void expressionIsEmbedded() {
		String input = "a${input1.concat('a')}c";
		ExpressionResolver resolver = new ExpressionResolver();
		ExpressionContext context = new ExpressionContext();
		context.add("input1", "bl");

		String resolved = resolver.resolve(input, context);

		Assert.assertEquals("ablac", resolved);
	}

	@Test(expected = RuntimeException.class)
	public void variableNotInContext() {
		String input = "${input2.concat('a')}";
		ExpressionResolver resolver = new ExpressionResolver();
		ExpressionContext context = new ExpressionContext();
		context.add("input1", "bl");

		resolver.resolve(input, context);
	}

}

Maven Dependencies

<dependency>
    <groupId>de.odysseus.juel</groupId>
    <artifactId>juel-api</artifactId>
    <version>2.2.7</version>
</dependency>
<dependency>
    <groupId>de.odysseus.juel</groupId>
    <artifactId>juel-impl</artifactId>
    <version>2.2.7</version>
</dependency>