org.springframework.binding.expression.beanwrapper
Class BeanWrapperExpression

java.lang.Object
  org.springframework.binding.expression.beanwrapper.BeanWrapperExpression

All Implemented Interfaces:

Expression

public class BeanWrapperExpression
extends java.lang.Object
implements Expression

An expression that delegates to a bean wrapper to evaluate or set a property of a context. Also supports the configuration of a ConversionService to allow StringToObject type conversion to occur as part of setting a property. The StringToObject ConversionExecutors are automatically adapted and registered as PropertyEditors. Mainly exists to take advantage of BeanWrapper's unique property access features as an Expression implementation, notably the ability to infer types of generic collections and maps and perform type coersion on collection elements when setting values. Note that Spring's BeanWrapper is not a full-blown EL implementation: it only supports property access, and does not support method invocation, arithmetic operations, or logic operations.

Author:

Keith Donald, Scott Andrews

Constructor Summary

BeanWrapperExpression(java.lang.String expression, ConversionService conversionService)
Creates a new bean wrapper expression.

Method Summary

boolean	equals(java.lang.Object o)
java.lang.String	getExpressionString() Returns the original string used to create this expression, unmodified.
java.lang.Object	getValue(java.lang.Object context) Evaluate this expression in the provided context and return the result of evaluation.
java.lang.Class<?>	getValueType(java.lang.Object context) Returns the most general type that can be passed to the Expression.setValue(Object, Object) method for the given context.
int	hashCode()
void	setAutoGrowCollectionLimit(int autoGrowCollectionLimit) Specify a limit for array and collection auto-growing.
void	setAutoGrowNestedPaths(boolean autoGrowNestedPaths) Set whether this BeanWrapper should attempt to "auto-grow" a nested path that contains a null value.
void	setValue(java.lang.Object context, java.lang.Object value) Set this expression in the provided context to the value provided.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

BeanWrapperExpression

public BeanWrapperExpression(java.lang.String expression,
                             ConversionService conversionService)

Creates a new bean wrapper expression.

Parameters:

expression - the property expression string

conversionService - the conversion service containing converters to use as PropertyEditors for type conversion

Method Detail

setAutoGrowNestedPaths

public void setAutoGrowNestedPaths(boolean autoGrowNestedPaths)

Set whether this BeanWrapper should attempt to "auto-grow" a nested path that contains a null value.

If "true", a null path location will be populated with a default object value and traversed instead of resulting in a NullValueInNestedPathException. Turning this flag on also enables auto-growth of collection elements when accessing an out-of-bounds index.

Default is "false" on a plain BeanWrapper.

setAutoGrowCollectionLimit

public void setAutoGrowCollectionLimit(int autoGrowCollectionLimit)

Specify a limit for array and collection auto-growing.

Default is unlimited on a plain BeanWrapper.

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

getValue

public java.lang.Object getValue(java.lang.Object 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 to evaluate this expression in

Returns:

the evaluation result

Throws:

EvaluationException - an exception occurred during expression evaluation

setValue

public void setValue(java.lang.Object context,
                     java.lang.Object value)

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 on which the new value should be set

value - the new value to set

getValueType

public java.lang.Class<?> getValueType(java.lang.Object context)

Description copied from interface: Expression

Returns the most general type that can be passed to the Expression.setValue(Object, Object) method for the given context.

Specified by:

getValueType in interface Expression

Parameters:

context - the context to evaluate

Returns:

the most general type of value that can be set on this context, or null if the type information cannot be determined

getExpressionString

public java.lang.String getExpressionString()

Description copied from interface: Expression

Returns the original string used to create this expression, unmodified.

Specified by:

getExpressionString in interface Expression

Returns:

the original expression string

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object