Class ExpressionFactory

java.lang.Object
jakarta.el.ExpressionFactory
public abstract class ExpressionFactory extends Object
Factory for creating ValueExpression and MethodExpression instances, and for coercing objects to specific types. Implementations parse and compile EL expressions. Use newInstance() to obtain an instance using the standard discovery mechanism.
Since:
EL 2.1

  • Constructor Details

    • ExpressionFactory

      public ExpressionFactory()
      Constructs an ExpressionFactory. Subclasses should invoke this constructor to initialize the base factory state.

  • Method Details

    • newInstance

      public static ExpressionFactory newInstance()
      Create a new ExpressionFactory. The class to use is determined by the following search order:
      1. services API (META-INF/services/jakarta.el.ExpressionFactory)
      2. $JRE_HOME/lib/el.properties - key jakarta.el.ExpressionFactory
      3. jakarta.el.ExpressionFactory
      4. Platform default implementation - org.apache.el.ExpressionFactoryImpl
      Returns:
      the new ExpressionFactory

    • newInstance

      public static ExpressionFactory newInstance(Properties properties)
      Create a new ExpressionFactory passing in the provided Properties. Search order is the same as newInstance().
      Parameters:
      properties - the properties to be passed to the new instance (might be null)
      Returns:
      the new ExpressionFactory

    • createValueExpression

      public abstract ValueExpression createValueExpression(ELContext context, String expression, Class<?> expectedType)
      Create a new value expression.
      Parameters:
      context - The EL context for this evaluation
      expression - The String representation of the value expression
      expectedType - The expected type of the result of evaluating the expression
      Returns:
      A new value expression formed from the input parameters
      Throws:
      NullPointerException - If the expected type is null
      ELException - If there are syntax errors in the provided expression

    • createValueExpression

      public abstract ValueExpression createValueExpression(Object instance, Class<?> expectedType)
      Creates a ValueExpression that, when evaluated, returns the given instance of the specified type. This is a convenience method for creating a constant value expression without requiring an ELContext.
      Parameters:
      instance - the constant value to wrap
      expectedType - the expected type of the value
      Returns:
      a ValueExpression that returns the given instance when evaluated

    • createMethodExpression

      public abstract MethodExpression createMethodExpression(ELContext context, String expression, Class<?> expectedReturnType, Class<?>[] expectedParamTypes)
      Create a new method expression instance.
      Parameters:
      context - The EL context for this evaluation
      expression - The String representation of the method expression
      expectedReturnType - The expected type of the result of invoking the method
      expectedParamTypes - The expected types of the input parameters
      Returns:
      A new method expression formed from the input parameters.
      Throws:
      NullPointerException - If the expected parameters types are null
      ELException - If there are syntax errors in the provided expression

    • coerceToType

      public abstract <T> T coerceToType(Object obj, Class<T> expectedType)
      Coerce the supplied object to the requested type.
      Type Parameters:
      T - The type to which the object should be coerced
      Parameters:
      obj - The object to be coerced
      expectedType - The type to which the object should be coerced
      Returns:
      An instance of the requested type.
      Throws:
      ELException - If the conversion fails

    • getStreamELResolver

      public ELResolver getStreamELResolver()
      Returns an ELResolver capable of resolving properties on InputStream objects, enabling EL expressions to operate on stream types. This allows expressions to read data from input streams using standard property navigation syntax.
      Returns:
      the StreamELResolver, or null if not supported by this implementation
      Since:
      EL 3.0

    • getInitFunctionMap

      public Map<String,Method> getInitFunctionMap()
      Returns a map of function names to Method objects representing the standard EL functions that are available by default without explicit registration. Implementations can override this method to provide a set of built-in functions.
      Returns:
      a map of function names to methods, or null if no default functions are provided
      Since:
      EL 3.0