Package org.springframework.expression.spel.standard

Class SpelExpression

java.lang.Object
org.springframework.expression.spel.standard.SpelExpression
All Implemented Interfaces:
Expression
public class SpelExpression extends Object implements Expression
A SpelExpression represents a parsed (valid) expression that is ready to be evaluated in a specified context. An expression can be evaluated standalone or in a specified context. During expression evaluation the context may be asked to resolve references to types, beans, properties, and methods.
Since:
3.0
Author:
Andy Clement, Juergen Hoeller, Sam Brannen

  • Constructor Details

  • Method Details

    • setEvaluationContext

      public void setEvaluationContext(EvaluationContext evaluationContext)
      Set the evaluation context that will be used if none is specified on an evaluation call.
      Parameters:
      evaluationContext - the evaluation context to use

    • getEvaluationContext

      public EvaluationContext getEvaluationContext()
      Return the default evaluation context that will be used if none is supplied on an evaluation call.
      Returns:
      the default evaluation context

    • getExpressionString

      public String getExpressionString()
      Description copied from interface: Expression
      Return the original string used to create this expression (unmodified).
      Specified by:
      getExpressionString in interface Expression
      Returns:
      the original expression string

    • getValue

      @Nullable public Object getValue() throws EvaluationException
      Description copied from interface: Expression
      Evaluate this expression in the default standard context.
      Specified by:
      getValue in interface Expression
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable public <T> T getValue(@Nullable Class<T> expectedResultType) throws EvaluationException
      Description copied from interface: Expression
      Evaluate this 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 thrown.
      Specified by:
      getValue in interface Expression
      Parameters:
      expectedResultType - the type the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable public Object getValue(@Nullable Object rootObject) throws EvaluationException
      Description copied from interface: Expression
      Evaluate this expression against the specified root object.
      Specified by:
      getValue in interface Expression
      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 public <T> T getValue(@Nullable Object rootObject, @Nullable Class<T> expectedResultType) throws EvaluationException
      Description copied from interface: Expression
      Evaluate this 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 thrown.
      Specified by:
      getValue in interface Expression
      Parameters:
      rootObject - the root object against which to evaluate the expression
      expectedResultType - the type the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable public Object getValue(EvaluationContext context) throws EvaluationException
      Description copied from interface: Expression
      Evaluate this expression in the provided context and return the result of evaluation.
      Specified by:
      getValue in interface Expression
      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 public <T> T getValue(EvaluationContext context, @Nullable Class<T> expectedResultType) throws EvaluationException
      Description copied from interface: Expression
      Evaluate this expression in the provided context which can resolve references to properties, methods, types, etc. The type of the evaluation result is expected to be of a particular type, and an exception will be thrown if it is not and cannot be converted to that type.
      Specified by:
      getValue in interface Expression
      Parameters:
      context - the context in which to evaluate the expression
      expectedResultType - the type the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValue

      @Nullable public Object getValue(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Description copied from interface: Expression
      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.
      Specified by:
      getValue in interface Expression
      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 public <T> T getValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Class<T> expectedResultType) throws EvaluationException
      Description copied from interface: Expression
      Evaluate this expression in the provided context which can resolve references to properties, methods, types, etc. The type of the evaluation result is expected to be of a particular type, and an exception will be thrown if it is not and cannot be converted to that type.j

      The supplied root object overrides any specified in the supplied context.

      Specified by:
      getValue in interface Expression
      Parameters:
      context - the context in which to evaluate the expression
      rootObject - the root object against which to evaluate the expression
      expectedResultType - the type the caller would like the result to be
      Returns:
      the evaluation result
      Throws:
      EvaluationException - if there is a problem during evaluation

    • getValueType

      @Nullable public Class<?> getValueType() throws EvaluationException
      Description copied from interface: Expression
      Return the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method using the default context.
      Specified by:
      getValueType in interface Expression
      Returns:
      the most general type of value that can be set in this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueType

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

    • getValueType

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

    • getValueType

      @Nullable public Class<?> getValueType(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Description copied from interface: Expression
      Return the most general type that can be passed to the Expression.setValue(EvaluationContext, Object, Object) method for the given context.

      The supplied root object overrides any specified in the supplied context.

      Specified by:
      getValueType in interface Expression
      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 in this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueTypeDescriptor

      @Nullable public TypeDescriptor getValueTypeDescriptor() throws EvaluationException
      Description copied from interface: Expression
      Return a descriptor for the most general type that can be passed to one of the setValue(...) methods using the default context.
      Specified by:
      getValueTypeDescriptor in interface Expression
      Returns:
      a type descriptor for values that can be set in this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • getValueTypeDescriptor

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

    • getValueTypeDescriptor

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

    • getValueTypeDescriptor

      @Nullable public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Description copied from interface: Expression
      Return a descriptor for the most general type that can be passed to the Expression.setValue(EvaluationContext, Object, Object) method for the given context.

      The supplied root object overrides any specified in the supplied context.

      Specified by:
      getValueTypeDescriptor in interface Expression
      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 in this context
      Throws:
      EvaluationException - if there is a problem determining the type

    • isWritable

      public boolean isWritable(@Nullable Object rootObject) throws EvaluationException
      Description copied from interface: Expression
      Determine if this expression can be written to, i.e. setValue() can be called.
      Specified by:
      isWritable in interface Expression
      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

      public boolean isWritable(EvaluationContext context) throws EvaluationException
      Description copied from interface: Expression
      Determine if this expression can be written to, i.e. setValue() can be called.
      Specified by:
      isWritable in interface Expression
      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

      public boolean isWritable(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException
      Description copied from interface: Expression
      Determine if this expression can be written to, i.e. setValue() can be called.

      The supplied root object overrides any specified in the supplied context.

      Specified by:
      isWritable in interface Expression
      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

      public void setValue(@Nullable Object rootObject, @Nullable Object value) throws EvaluationException
      Description copied from interface: Expression
      Set this expression in the provided context to the value provided.
      Specified by:
      setValue in interface Expression
      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

      public void setValue(EvaluationContext context, @Nullable Object value) throws EvaluationException
      Description copied from interface: Expression
      Set this expression in the provided context to the value provided.
      Specified by:
      setValue in interface Expression
      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

      public void setValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Object value) throws EvaluationException
      Description copied from interface: Expression
      Set this expression in the provided context to the value provided.

      The supplied root object overrides any specified in the supplied context.

      Specified by:
      setValue in interface Expression
      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

    • compileExpression

      public boolean compileExpression()
      Perform expression compilation. This will only succeed once exit descriptors for all nodes have been determined. If the compilation fails and has failed more than 100 times the expression is no longer considered suitable for compilation.
      Returns:
      whether this expression has been successfully compiled

    • revertToInterpreted

      public void revertToInterpreted()
      Cause an expression to revert to being interpreted if it has been using a compiled form. It also resets the compilation attempt failure count (an expression is normally no longer considered compilable if it cannot be compiled after 100 attempts).

    • getAST

      public SpelNode getAST()
      Return the Abstract Syntax Tree for the expression.

    • toStringAST

      public String toStringAST()
      Produce a string representation of the Abstract Syntax Tree for the expression. This should ideally look like the input expression, but properly formatted since any unnecessary whitespace will have been discarded during the parse of the expression.
      Returns:
      the string representation of the AST