Spring DI (Beans) with multiple concretes…picking one of them - dependency-injection

Question

I have a similar question here
Guice with multiple concretes......picking one of them
with a solution for Guice.
But I have a different project using spring di (beans), but with the same kind of issue.
I have an interface with N number of concretes. (3 here)
public interface OrderProcessorInterface {
void ProcessOrder(String preferredShipperAbbreviation, Order ord);
}
public class FedExShipper implements ShipperInterface {
private Log logger;
public FedExShipper(Log lgr) {
if (null == lgr) {
throw new IllegalArgumentException("Log is null");
}
this.logger = lgr;
}
public void ShipOrder(Order ord) {
this.logger.info("I'm shipping the Order with FexEx");
}
}
public class UpsShipper implements ShipperInterface {
private Log logger;
public UpsShipper(Log lgr) {
if (null == lgr) {
throw new IllegalArgumentException("Log is null");
}
this.logger = lgr;
}
public void ShipOrder(Order ord) {
this.logger.info("I'm shipping the Order with Ups");
}
}
public class UspsShipper implements ShipperInterface {
private Log logger;
public UspsShipper(Log lgr) {
if (null == lgr) {
throw new IllegalArgumentException("Log is null");
}
this.logger = lgr;
}
public void ShipOrder(Order ord) {
this.logger.info("I'm shipping the Order with Usps");
}
}
........
Then I have a class that needs to know about ALL THREE concretes.
import java.util.Collection;
import java.util.Set;
import org.apache.commons.logging.Log;
public class OrderProcessorImpl implements OrderProcessorInterface {
private Log logger;
private java.util.Map<String, javax.inject.Provider<ShipperInterface>> shipperProviderMap;
public OrderProcessorImpl(Log lgr, java.util.Map<String, javax.inject.Provider<ShipperInterface>> spMap) {
if (null == lgr) {
throw new IllegalArgumentException("Log is null");
}
if (null == spMap) {
throw new IllegalArgumentException("Provider<ShipperInterface> is null");
}
this.logger = lgr;
this.shipperProviderMap = spMap;
}
public void ProcessOrder(String preferredShipperAbbreviation, Order ord) {
this.logger.info(String.format("About to ship. (%1s)", preferredShipperAbbreviation));
ShipperInterface foundShipperInterface = this.FindShipperInterface(preferredShipperAbbreviation);
foundShipperInterface.ShipOrder(ord);
}
private ShipperInterface FindShipperInterface(String preferredShipperAbbreviation) {
ShipperInterface foundShipperInterface = this.shipperProviderMap.get(preferredShipperAbbreviation).get();
if (null == foundShipperInterface) {
throw new NullPointerException(
String.format("ShipperInterface not found in shipperProviderMap. ('%1s')", preferredShipperAbbreviation));
}
return foundShipperInterface;
}
}
=============
Basically, I want to call the method, pass in a string argument, and have it choose the concrete for me. (if my real code, this is via a database value, but for the demo code, this is good enough)
Order ord = new Order();
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
BeanFactory factory = context;
OrderProcessorInterface opi = context.getBean(OrderProcessorImpl.class);
opi.ProcessOrder("myFedExName", ord); /* friendlyName would be nice, but fully qualified concrete name also assceptable */
My Spring Configuration is via xml:
<bean id="theLoggerBean"
class="org.apache.commons.logging.impl.Log4JLogger">
<constructor-arg value="log" />
</bean>
<bean id="fedExBean"
class="com.me.FedExShipper">
<constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>
<bean id="uspsExBean"
class="com.me.FedExShipper">
<constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>
<bean id="upsExBean"
class="com.me.FedExShipper">
<constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>
..........
================================
<bean id="OrderProcessorImplBean"
class="com.me.OrderProcessorImpl">
<constructor-arg ref="theLoggerBean"></constructor-arg>
<constructor-arg ref="How do I do N Number of ShipperInterfaces Here ??"></constructor-arg>
</bean>
So I want to xml configure the 3 concretes.
And then inject them into the class.
But where I have "How do I do N Number of ShipperInterfaces Here ??", I have no idea what to do.
JSR 330 implementation preferred, but will take anything.
THANKS
Note, in the other question (the Guice one), this was also a possiblity for the constructor of the OrderProcessor:
public class OrderProcessorImpl implements OrderProcessorInterface {
private Log logger;
Set<ShipperInterface> shippers;
public OrderProcessorImpl(Log lgr, Set<ShipperInterface> shprs) {
if (null == lgr) {
throw new IllegalArgumentException("Log is null");
}
if (null == shprs) {
throw new IllegalArgumentException("ShipperInterface(s) is null");
}
this.logger = lgr;
this.shippers = shprs;
}
public void ProcessOrder(String preferredShipperAbbreviation, Order ord) {
this.logger.info(String.format("About to ship. (%1s)", preferredShipperAbbreviation));
for (ShipperInterface sh : shippers) {
this.logger.info(String.format("ShipperInterface . (%1s)", sh.getClass().getSimpleName()));
}
}
}

Answer 1

Something like this should work. This uses #Autowired and not xml configuration:
#org.springframework.stereotype.Service
public class OrderProcessorImpl implements OrderProcessorInterface {
private List<ShipperInterface> shipperProviders;
private Map<String, ShipperInterface> shipperProvidersMap = new HashMap<>();
#Autowired
public void setShipperProviders(List<ShipperInterface> shipperProviders) {
this.shipperProviders= shipperProviders;
this.shipperProviders.stream().forEach(p->shipperProvidersMap .put(/* your code for getting the key */, p));
}
Gradle dependency hint:
compile group: 'org.springframework', name: 'spring-context', version: '5.1.9.RELEASE'

Answer 2

I think I have something that works:
beans.xml (note the "util" extras in the namespace declares)
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-2.5.xsd">
<bean id="theLoggerBean"
class="org.apache.commons.logging.impl.Log4JLogger">
<constructor-arg value="log" />
</bean>
<bean id="fedExShipperBean"
class="com.me.shipping.FedExShipper">
<constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>
<bean id="upsShipperBean"
class="com.me.shipping.UpsShipper">
<constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>
<bean id="uspsShipperBean"
class="com.me.shipping.UspsShipper">
<constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>
<util:map id="shipperInterfaceMap" key-type="java.lang.String"
value-type="com.me.shipping.interfaces.ShipperInterface">
<entry key="fedexFriendlyName" value-ref="fedExShipperBean" />
<entry key="upsFriendlyName" value-ref="upsShipperBean" />
<entry key="uspsFriendlyName" value-ref="uspsShipperBean" />
</util:map>
<bean id="orderProcessorImplBean"
class="com.me.shipping.OrderProcessorImpl">
<constructor-arg ref="theLoggerBean"></constructor-arg>
<constructor-arg ref="shipperInterfaceMap"></constructor-arg>
</bean>
</beans>
and java
package com.me.shipping;
import java.util.Collection;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import com.me.shipping.interfaces.OrderProcessorInterface;
import com.me.shipping.interfaces.ShipperInterface;
import com.me.Models.Order;
public class OrderProcessorImpl implements OrderProcessorInterface {
private Log logger;
private java.util.Map<String, ShipperInterface> shipperInterfaceMap;
public OrderProcessorImpl(Log lgr, java.util.Map<String, ShipperInterface> siMap) {
if (null == lgr) {
throw new IllegalArgumentException("Log is null");
}
if (null == siMap) {
throw new IllegalArgumentException("Map<String, ShipperInterface> is null");
}
this.logger = lgr;
this.shipperInterfaceMap = siMap;
}
public void ProcessOrder(String preferredShipperAbbreviation, Order ord) {
this.logger.info(String.format("About to ship. (%1s)", preferredShipperAbbreviation));
ShipperInterface foundShipperInterface = this.FindShipperInterface(preferredShipperAbbreviation);
foundShipperInterface.ShipOrder(ord);
}
private ShipperInterface FindShipperInterface(String friendlyName)
{
ShipperInterface returnItem = null;
if (null != this.shipperInterfaceMap)
{
returnItem = this.shipperInterfaceMap.entrySet().stream()
.filter(e -> e.getKey().equalsIgnoreCase(friendlyName))
.map(Map.Entry::getValue)
.findFirst()
.orElse(null);
}
if (null == returnItem)
{
throw new NullPointerException(String.format("shipperProviderMap did not contain expected item. (Key='%s')", friendlyName));
}
return returnItem;
}
}
and "main" method
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
BeanFactory factory = context;
Order ord = new Order();
OrderProcessorInterface opi = context.getBean(OrderProcessorImpl.class);
opi.ProcessOrder("fedexFriendlyName", ord);