Dynamic lookup of properties from a secure-property-placeholder in a Mule flow

data.properties

number=![0J0O/Z2I0NzSJnpFF8cGOQ==]
bob=![665bhZoDiRU=]
alice=![IuCmQm1Dh6A=]

PropertiesAccessor.java

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.support.AbstractBeanFactory;

/**
 * Helper bean to allow indirect access to properties loaded by Spring property placeholders.
 * Code taken from StackOverflow (http://stackoverflow.com/a/17697586)
 */
public class PropertiesAccessor {

    private final AbstractBeanFactory beanFactory;

    private final Map<String,String> cache = new ConcurrentHashMap<String,String>(); 

    @Autowired
    protected PropertiesAccessor(AbstractBeanFactory beanFactory) {
        this.beanFactory = beanFactory; 
    } 

    public  String getProperty(String key) { 
        if(cache.containsKey(key)){ 
            return cache.get(key); 
        } 

        String foundProp = null; 
        try { 
            foundProp = beanFactory.resolveEmbeddedValue("${" + key.trim() + "}");        
            cache.put(key,foundProp);        
        } catch (IllegalArgumentException ex) { 
           // ok - property was not found 
        } 

        return foundProp; 
    } 
}

secure-property-placeholder.xml

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:context="http://www.springframework.org/schema/context"
	xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:secure-property-placeholder="http://www.mulesoft.org/schema/mule/secure-property-placeholder" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
	xmlns:spring="http://www.springframework.org/schema/beans" version="EE-3.5.2"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-current.xsd http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/secure-property-placeholder http://www.mulesoft.org/schema/mule/secure-property-placeholder/current/mule-secure-property-placeholder.xsd">

 	<spring:beans>
 	    <context:annotation-config />
 		<spring:bean id="propertiesAccessor" class="PropertiesAccessor" />
 	</spring:beans>
 	
    <secure-property-placeholder:config name="Secure_Property_Placeholder" 
    	encryptionAlgorithm="Blowfish" key="secretkey" 
    	location="data.properties" 
    	doc:name="Secure Property Placeholder"/>
	
	<!-- "Static" lookup of property -->
	<flow name="getNumber" doc:name="getNumber">
		<http:inbound-endpoint host="localhost" port="8081" path="getNumber" doc:name="HTTP"/>
		<set-payload value="The number is ${number}" doc:name="Set Payload"/>
	</flow>
	
	<!-- "Dynamic" lookup of property based on user input-->
	<flow name="getDynamicPin" doc:name="getDynamicPin">
		<http:inbound-endpoint host="localhost" port="8081" path="getDynamicPin" doc:name="HTTP"/>
		<choice >
			<when expression="#[message.inboundProperties.user]">
				<set-payload value="#[message.inboundProperties.user + ' has pin '+ app.registry.propertiesAccessor.getProperty(message.inboundProperties.user)]" doc:name="Set Payload"/>
			</when>
			<otherwise>
				<set-payload value="You have to provide a user"/>
			</otherwise>
		</choice>
	</flow>
</mule>