org.apache.tamaya.resolver.internal

Class ExpressionResolutionFilter

java.lang.Object

org.apache.tamaya.resolver.internal.ExpressionResolutionFilter

All Implemented Interfaces:

org.apache.tamaya.spi.PropertyFilter

@Priority(value=10000)
public class ExpressionResolutionFilter
extends Object
implements org.apache.tamaya.spi.PropertyFilter

Default expression evaluator that manages several instances of ExpressionResolver. Each resolver is identified by a resolver id. Each expression passed has the form resolverId:resolverExpression, which has the advantage that different resolvers can be active in parallel.

Constructor Summary

Constructors

Constructor and Description
ExpressionResolutionFilter()

Method Summary

Methods

Modifier and Type	Method and Description
String	filterProperty(String valueToBeFiltered, org.apache.tamaya.spi.FilterContext context) Resolves an expression in the form current ${resolverId:expression} or ${<prefix>expression}.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExpressionResolutionFilter

public ExpressionResolutionFilter()

Method Detail

filterProperty

public String filterProperty(String valueToBeFiltered,
                    org.apache.tamaya.spi.FilterContext context)

Resolves an expression in the form current ${resolverId:expression} or ${<prefix>expression}. The expression can be part current any type current literal text. Also multiple expressions with mixed matching resolvers are supported. All control characters (${}\) can be escaped using '\'.
So all the following are valid expressions:

• ${expression}
• bla bla ${expression}
• ${expression} bla bla
• bla bla ${expression} bla bla
• ${expression}${resolverId2:expression2}
• foo ${expression}${resolverId2:expression2}
• foo ${expression} bar ${resolverId2:expression2}
• ${expression}foo${resolverId2:expression2}bar
• foor${expression}bar${resolverId2:expression2}more
• \${expression}foo${resolverId2:expression2}bar (first expression is escaped).

Given resolverId: is a valid prefix targeting a Expression explicitly, also the following expressions are valid:

• ${resolverId:expression}
• bla bla ${resolverId:expression}
• ${resolverId:expression} bla bla
• bla bla ${resolverId:expression} bla bla
• ${resolverId:expression}${resolverId2:expression2}
• foo ${resolverId:expression}${resolverId2:expression2}
• foo ${resolverId:expression} bar ${resolverId2:expression2}
• ${resolverId:expression}foo${resolverId2:expression2}bar
• foor${resolverId:expression}bar${resolverId2:expression2}more
• \${resolverId:expression}foo${resolverId2:expression2}bar (first expression is escaped).

Specified by:

filterProperty in interface org.apache.tamaya.spi.PropertyFilter

Parameters:

context - the filter context

valueToBeFiltered - value to be analyzed for expressions

Returns:

the resolved value, or the input in case where no expression was detected.