SystemClassLoaderProperties

Current Stable Version is 1.0.0

DOC

Usage Example in a standalone Java application (programmatically)

public static void main(final String[] args) {
 // Install SystemClassLoaderProperties
 SystemClassLoaderProperties.getInstance().takeover();
 // Normal Usage
 System.setProperty("xxxxx", "value");
 System.out.println(System.getProperty("xxxxx"));
}

Usage Example in a standalone Java application (using a JavaAgent)

java -javaagent:<directory>/lib/systemclassloaderproperties-x.x.x.jar com.acme.YourClass

Usage Example in a Tomcat (using a JavaAgent)

# tomcat/bin/setenv.sh
CATALINA_OPTS="$CATALINA_OPTS -javaagent:<directory>/lib/systemclassloaderproperties-x.x.x.jar"

Proof Of Concept (Servlet Container / Tomcat)

Sample ClassLoader Hierarchy (Tomcat 7)

// Bootstrap
// |
// System
// |
// Common
// / \
// Webapp1 Webapp2

Dummy Test JSP (test.jsp) - show last value

<%
// One counter by each Webapp
Integer x = Integer.valueOf(System.getProperty("dummy.test", "0"))+1;
out.print(getClass().getClassLoader() + ":" + System.setProperty("dummy.test", String.valueOf(x)));
%>

Simple Test (bash/curl)

for j in a b c; do {
 for i in 1 2; do {
 curl http://localhost:8080/Webapp${i}/test.jsp
 } done
} done

Output will be:

org.apache.jasper.servlet.JasperLoader@7064ce:null
org.apache.jasper.servlet.JasperLoader@7df6d9:null
org.apache.jasper.servlet.JasperLoader@7064ce:1
org.apache.jasper.servlet.JasperLoader@7df6d9:1
org.apache.jasper.servlet.JasperLoader@7064ce:2
org.apache.jasper.servlet.JasperLoader@7df6d9:2

Note about Security: You may need a SecurityManager if you want strong security (this "light isolation" can be easily circumvented in a hostile environment).

MAVEN

<dependency>
 <groupId>org.javastack</groupId>
 <artifactId>systemclassloaderproperties</artifactId>
 <version>1.0.0</version>
</dependency>