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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.config.expression;
import com.tangosol.coherence.config.Config;
/**
* A {@link SystemPropertyParameterResolver} is a {@link ParameterResolver} that is
* based on property methods on {@link System}.
*
* Replaces {@link PropertiesParameterResolver( java.util.Properties )} since it required
* read and write access for all Properties for simple property access.
* {@link SystemPropertyParameterResolver#resolve(String)} only requires read access for property specified.
*
* @author jf 2015.04.15
* @since Coherence 12.2.1
*/
public class SystemPropertyParameterResolver
implements ParameterResolver
{
// ----- ParameterResolver methods --------------------------------------
/**
* Resolve Coherence system property sName
*
* @param sName system property name
*
* @return a {@link Parameter} representing the value of sName or
* null if system property not found or if SecurityException was handled.
*/
@Override
public Parameter resolve(String sName)
{
String sValue = Config.getProperty(sName);
return sValue == null ? null : new Parameter(sName, sValue);
}
// ----- SystemPropertyParameterResolver methods ------------------------
/**
* Return property's value as requested type.
*
* @param sName property name
* @param clzTypeValue coerce system property's value from string to instance of this class
* @param property value's target type
* @return null if property has no value or return property's value coerced from string
* to requested type.
*
* Throws exceptions listed in {@link Value#as(Class)} when coercion fails.
*/
@SuppressWarnings("unchecked")
public T resolve(String sName, Class clzTypeValue)
{
Parameter p = resolve(sName);
return p == null ? null : p.evaluate(this).as(clzTypeValue);
}
//----- constants -------------------------------------------------------
/**
* This singleton instance of the {@link SystemPropertyParameterResolver}.
*/
public static final SystemPropertyParameterResolver INSTANCE = new SystemPropertyParameterResolver();
}