Object eval(Object.. args); // массив объектов на входе

<label>CONCAT(GETUSERNAME({userId}), "_", GETHOSTNAME(), "_")</label>

<label>1 + 3 + SIN({someVarName})</label>

public final class Calculator {
  
  /** Parsers {@code source} and evaluates to an {@link Integer}. */
  public static int evaluate(String source) {
    return parser().parse(source);
  }
  
  static final Parser<Integer> NUMBER = Scanners.INTEGER.map(Integer::valueOf);
  
  static final BinaryOperator<Integer> PLUS = (a, b) -> a + b;
  
  static final BinaryOperator<Integer> MINUS = (a, b) -> a - b;
  
  static final BinaryOperator<Integer> MUL = (a, b) -> a * b;
  
  static final BinaryOperator<Integer> DIV = (a, b) -> a / b;
  
  static final BinaryOperator<Integer> MOD = (a, b) -> a % b;
  
  static final UnaryOperator<Integer> NEG = a -> -a;
  
  private static <T> Parser<T> op(char ch, T value) {
    return isChar(ch).retn(value);
  }
  
  static Parser<Integer> parser() {
    Parser.Reference<Integer> ref = Parser.newReference();
    Parser<Integer> term = ref.lazy().between(isChar('('), isChar(')')).or(NUMBER);
    Parser<Integer> parser = new OperatorTable<Integer>()
        .prefix(op('-', NEG), 100)
        .infixl(op('+', PLUS), 10)
        .infixl(op('-', MINUS), 10)
        .infixl(op('*', MUL), 20)
        .infixl(op('/', DIV), 20)
        .infixl(op('%', MOD), 20)
        .build(term);
    ref.set(parser);
    return parser;
  }
}

10.5.12 Functions

You can extend SpEL by registering user defined functions that can be called within the expression string. The function is registered with the StandardEvaluationContext using the method.

public void registerFunction(String name, Method m)

This method is then registered with the evaluation context and can be used within an expression string.

ExpressionParser parser = new SpelExpressionParser();
StandardEvaluationContext context = new StandardEvaluationContext();

context.registerFunction("reverseString",
    StringUtils.class.getDeclaredMethod("reverseString", new Class[] { String.class }));

String helloWorldReversed = parser.parseExpression(
    "#reverseString('hello')").getValue(context, String.class);