Package org.springframework.expression

Interface PropertyAccessor

All Known Subinterfaces:
CompilablePropertyAccessor
All Known Implementing Classes:
BeanExpressionContextAccessor, BeanFactoryAccessor, DataBindingPropertyAccessor, EnvironmentAccessor, MapAccessor, ReflectivePropertyAccessor, ReflectivePropertyAccessor.OptimalPropertyAccessor
public interface PropertyAccessor
A property accessor is able to read from (and possibly write to) an object's properties.

This interface places no restrictions, and so implementors are free to access properties directly as fields or through getters or in any other way they see as appropriate.

A resolver can optionally specify an array of target classes for which it should be called. However, if it returns null from getSpecificTargetClasses(), it will be called for all property references and given a chance to determine if it can read or write them.

Property resolvers are considered to be ordered, and each will be called in turn. The only rule that affects the call order is that any resolver naming the target class directly in getSpecificTargetClasses() will be called first, before the general resolvers.

Since:
3.0
Author:
Andy Clement

  • Method Details

    • getSpecificTargetClasses

      @Nullable Class<?>[] getSpecificTargetClasses()
      Return an array of classes for which this resolver should be called.

      Returning null indicates this is a general resolver that can be called in an attempt to resolve a property on any type.

      Returns:
      an array of classes that this resolver is suitable for (or null if a general resolver)

    • canRead

      boolean canRead(EvaluationContext context, @Nullable Object target, String name) throws AccessException
      Called to determine if a resolver instance is able to access a specified property on a specified target object.
      Parameters:
      context - the evaluation context in which the access is being attempted
      target - the target object upon which the property is being accessed
      name - the name of the property being accessed
      Returns:
      true if this resolver is able to read the property
      Throws:
      AccessException - if there is any problem determining whether the property can be read

    • read

      TypedValue read(EvaluationContext context, @Nullable Object target, String name) throws AccessException
      Called to read a property from a specified target object. Should only succeed if canRead(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String) also returns true.
      Parameters:
      context - the evaluation context in which the access is being attempted
      target - the target object upon which the property is being accessed
      name - the name of the property being accessed
      Returns:
      a TypedValue object wrapping the property value read and a type descriptor for it
      Throws:
      AccessException - if there is any problem accessing the property value

    • canWrite

      boolean canWrite(EvaluationContext context, @Nullable Object target, String name) throws AccessException
      Called to determine if a resolver instance is able to write to a specified property on a specified target object.
      Parameters:
      context - the evaluation context in which the access is being attempted
      target - the target object upon which the property is being accessed
      name - the name of the property being accessed
      Returns:
      true if this resolver is able to write to the property
      Throws:
      AccessException - if there is any problem determining whether the property can be written to

    • write

      void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object newValue) throws AccessException
      Called to write to a property on a specified target object. Should only succeed if canWrite(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String) also returns true.
      Parameters:
      context - the evaluation context in which the access is being attempted
      target - the target object upon which the property is being accessed
      name - the name of the property being accessed
      newValue - the new value for the property
      Throws:
      AccessException - if there is any problem writing to the property value