Package org.springframework.expression

Interface Expression

All Known Implementing Classes:
CompositeStringExpression, LiteralExpression, SpelExpression
public interface Expression
An expression capable of evaluating itself against context objects. Encapsulates the details of a previously parsed expression string. Provides a common abstraction for expression evaluation.
Since:
3.0
Author:
Keith Donald, Andy Clement, Juergen Hoeller

  • Method Details

    • getExpressionString

      String getExpressionString()
      Return the original string used to create this expression (unmodified).
      Returns:
      the original expression string

    • getValue

      @Nullable Object getValue() throws EvaluationException
      Evaluate this expression in the default standard context.
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable <T> T getValue(@Nullable Class<T> desiredResultType) throws EvaluationException
      Evaluate the expression in the default context. If the result of the evaluation does not match (and cannot be converted to) the expected result type then an exception will be returned.
      Parameters:
      desiredResultType - the class the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable Object getValue(@Nullable Object rootObject) throws EvaluationException
      Evaluate this expression against the specified root object.
      Parameters:
      rootObject - the root object against which to evaluate the expression
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable <T> T getValue(@Nullable Object rootObject, @Nullable Class<T> desiredResultType) throws EvaluationException
      Evaluate the expression in the default context against the specified root object. If the result of the evaluation does not match (and cannot be converted to) the expected result type then an exception will be returned.
      Parameters:
      rootObject - the root object against which to evaluate the expression
      desiredResultType - the class the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable Object getValue(EvaluationContext context) throws EvaluationException
      Evaluate this expression in the provided context and return the result of evaluation.
      Parameters:
      context - the context in which to evaluate the expression
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable Object getValue(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Evaluate this expression in the provided context and return the result of evaluation, but use the supplied root context as an override for any default root object specified in the context.
      Parameters:
      context - the context in which to evaluate the expression
      rootObject - the root object against which to evaluate the expression
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable <T> T getValue(EvaluationContext context, @Nullable Class<T> desiredResultType) throws EvaluationException
      Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc. The type of the evaluation result is expected to be of a particular class and an exception will be thrown if it is not and cannot be converted to that type.
      Parameters:
      context - the context in which to evaluate the expression
      desiredResultType - the class the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable <T> T getValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Class<T> desiredResultType) throws EvaluationException
      Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc. The type of the evaluation result is expected to be of a particular class and an exception will be thrown if it is not and cannot be converted to that type. The supplied root object overrides any default specified on the supplied context.
      Parameters:
      context - the context in which to evaluate the expression
      rootObject - the root object against which to evaluate the expression
      desiredResultType - the class the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValueType

      @Nullable Class<?> getValueType() throws EvaluationException
      Return the most general type that can be passed to a setValue(java.lang.Object, java.lang.Object) method using the default context.
      Returns:
      the most general type of value that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueType

      @Nullable Class<?> getValueType(@Nullable Object rootObject) throws EvaluationException
      Return the most general type that can be passed to the setValue(Object, Object) method using the default context.
      Parameters:
      rootObject - the root object against which to evaluate the expression
      Returns:
      the most general type of value that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueType

      @Nullable Class<?> getValueType(EvaluationContext context) throws EvaluationException
      Return the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
      Parameters:
      context - the context in which to evaluate the expression
      Returns:
      the most general type of value that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueType

      @Nullable Class<?> getValueType(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Return the most general type that can be passed to the setValue(EvaluationContext, Object, Object) method for the given context. The supplied root object overrides any specified in the context.
      Parameters:
      context - the context in which to evaluate the expression
      rootObject - the root object against which to evaluate the expression
      Returns:
      the most general type of value that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueTypeDescriptor

      @Nullable TypeDescriptor getValueTypeDescriptor() throws EvaluationException
      Return the most general type that can be passed to a setValue(java.lang.Object, java.lang.Object) method using the default context.
      Returns:
      a type descriptor for values that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueTypeDescriptor

      @Nullable TypeDescriptor getValueTypeDescriptor(@Nullable Object rootObject) throws EvaluationException
      Return the most general type that can be passed to the setValue(Object, Object) method using the default context.
      Parameters:
      rootObject - the root object against which to evaluate the expression
      Returns:
      a type descriptor for values that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueTypeDescriptor

      @Nullable TypeDescriptor getValueTypeDescriptor(EvaluationContext context) throws EvaluationException
      Return the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
      Parameters:
      context - the context in which to evaluate the expression
      Returns:
      a type descriptor for values that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueTypeDescriptor

      @Nullable TypeDescriptor getValueTypeDescriptor(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Return the most general type that can be passed to the setValue(EvaluationContext, Object, Object) method for the given context. The supplied root object overrides any specified in the context.
      Parameters:
      context - the context in which to evaluate the expression
      rootObject - the root object against which to evaluate the expression
      Returns:
      a type descriptor for values that can be set on this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • isWritable

      boolean isWritable(@Nullable Object rootObject) throws EvaluationException
      Determine if an expression can be written to, i.e. setValue() can be called.
      Parameters:
      rootObject - the root object against which to evaluate the expression
      Returns:
      true if the expression is writable; false otherwise
      Throws:
      EvaluationException - if there is a problem determining if it is writable

    • isWritable

      boolean isWritable(EvaluationContext context) throws EvaluationException
      Determine if an expression can be written to, i.e. setValue() can be called.
      Parameters:
      context - the context in which the expression should be checked
      Returns:
      true if the expression is writable; false otherwise
      Throws:
      EvaluationException - if there is a problem determining if it is writable

    • isWritable

      boolean isWritable(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Determine if an expression can be written to, i.e. setValue() can be called. The supplied root object overrides any specified in the context.
      Parameters:
      context - the context in which the expression should be checked
      rootObject - the root object against which to evaluate the expression
      Returns:
      true if the expression is writable; false otherwise
      Throws:
      EvaluationException - if there is a problem determining if it is writable

    • setValue

      void setValue(@Nullable Object rootObject, @Nullable Object value) throws EvaluationException
      Set this expression in the provided context to the value provided.
      Parameters:
      rootObject - the root object against which to evaluate the expression
      value - the new value
      Throws:
      EvaluationException - if there is a problem during evaluation

    • setValue

      void setValue(EvaluationContext context, @Nullable Object value) throws EvaluationException
      Set this expression in the provided context to the value provided.
      Parameters:
      context - the context in which to set the value of the expression
      value - the new value
      Throws:
      EvaluationException - if there is a problem during evaluation

    • setValue

      void setValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Object value) throws EvaluationException
      Set this expression in the provided context to the value provided. The supplied root object overrides any specified in the context.
      Parameters:
      context - the context in which to set the value of the expression
      rootObject - the root object against which to evaluate the expression
      value - the new value
      Throws:
      EvaluationException - if there is a problem during evaluation