Hi All, I was trying to figure out how we can control message replacement in Spring. It seems little complicated to me. Let me know if anyone can throw light on the following.
Coding is done based on the materials suggested in Appress Pro Spring book.
ReplacementTarget.java
package com.doogle.spring.chapter4.mi;
/**
* @author DOOGLE
*
*/
public class ReplacementTarget {
public int formatMessage(int a)
{
return 100000 + a + 100000;
}
public
String formatMessage(String msg)
{
return "<h4>" + msg + "</h4>";
}
}
FormatMessageReplacer.java
package com.doogle.spring.chapter4.mi;
import java.lang.reflect.Method;
import org.springframework.beans.factory.support.MethodReplacer;
/**
* @author DOOGLE
*
*/
public class FormatMessageReplacer implements MethodReplacer{
public Object reimplement (Object arg0,Method method,Object [] args) throws Throwable
{
if(method.getReturnType() == int.class)
{
return (int)(Integer)args[0];
}
else if (method.getReturnType() == String.class)
{
return (String)args[0];
}
else
return "NA";
/*
As expected, the output from the replacementTarget bean reflects the overridden implementation
that the MethodReplacer provides. Interestingly, though, the dynamically replaced method is more than
three times slower than the statically defined method. Removing the check for a valid method in the
MethodReplacer made a negligible difference across a number of executions, so we can conclude that
most of the overhead is in the CGLIB subclass
*/
}
}
replacement.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.1.xsd">
<bean id="methodReplacer" class="com.doogle.spring.chapter4.mi.FormatMessageReplacer"/>
<bean id="replacementTarget" class="com.doogle.spring.chapter4.mi.ReplacementTarget">
<replaced-method name="formatMessage" replacer="methodReplacer">
<arg-type>int</arg-type>
</replaced-method>
</bean>
<bean id="standardTarget" class="com.doogle.spring.chapter4.mi.ReplacementTarget"/>
</beans>
MethodReplacementExample.java
/**
*
*/
package com.doogle.spring.chapter4.mi;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.util.StopWatch;
/**
* @author DOOGLE
*
*/
public class MethodReplacementExample {
public static void main(String[] args) {
GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
ctx.load("classpath:replacement.xml");
ctx.refresh();
ReplacementTarget replacementTarget = (ReplacementTarget)ctx.getBean("replacementTarget");
ReplacementTarget standardTarget = (ReplacementTarget)ctx.getBean("standardTarget");
displayInfo(replacementTarget);
displayInfo(standardTarget);
}
private static void displayInfo(ReplacementTarget replacementTarget)
{
System.out.println(replacementTarget.formatMessage(2));
System.out.println(replacementTarget.formatMessage("2"));
// System.out.println(replacementTarget.formatMessage("Formating message and checking for message replacement"));
StopWatch stopWatch = new StopWatch();
stopWatch.start("perfTesting");
// Object obj = new Object();
for(int i=0;i<1000000 ; i++)
{
String out = replacementTarget.formatMessage("foo-bar");
}
stopWatch.stop();
System.out.println("1000000 invocations took: " + stopWatch.getTotalTimeMillis()+ " ms");
}
}
Based on my understanding the replacement should work on when the argument type is int. Not when we have the argument type as String.
I tried changing the same in configuration file. Once you write <arg-type> the irrespective of the value you have the method getting replaced.
I gave the value asd for the arg-type still the method got replaced. Can anyone explain how to restrict method replacement in spring.
Regards
Debabrabrta
