Java Development Techniques of Injecting Code Into Running JVM

Java Development can bring forth many issues and aspects at times of advanced coding for running JVM. In this blog, weare going to discuss techniques of injecting codes into running JVM through Java instrumentation and attaching instrumentation agent. The java.lang.instrument.Instrumentation class in Java Application Development can be used to inject code in running JVM through the following methods.

  • The first method of injecting code in running JVM is implemented taking into consideration that the third party application is up and running. So, to inject the code a Java agent jar file is createdfollowing the agentmain method. After the code is injected, the agentmain method is referenced. The agentmain method forms the entry point of the automation code. Presently the code that is written in both the agentmain and the third party application will reside in the JVM. This will enable the automation code to directly check the objects that are running in the third party application. The drawbacks of this method include the fact that all JVMs do not support this method of injecting code.Moreover, the JDKmust be installed prior to running this code injecting method.
  • The next method of injecting code is to be executed while initializing the JVM. In this method prior to the third party application, the Java agent is run. Thus, the premain method is referenced much before the third party application. Much like the previous method, the automation code is run considering the premain to be the entry point. They both are run on the same JVM, whichlets the automation code to find the user interface objects without any trouble.There are even methods that let you analyze the objects and carry on the operations on them.

The simple steps of this method allows easy execution through mouse click. In addition to the other features of this method, the proper functioning of the steps does not depend on the location of the application or on the graphical resolution settings. This method helps in the automation of all kinds and forms of Java based applications as long as, prior to the launch of the application the variable Java_Tool_Options is set with the value javaagent:”<PATH TO JAVAAGENT>”. The range of the variable can differ according to the requirement of the application. However, the drawbacks of this methodmay include the dependency of the method on the additional permission granting step,that is required for the socket connection to be established. Alsofor the application, there are a lot of permission granting steps that increase the restrictions of this method.

More capabilities and features will be announced by Oracle soon. Aegis Java development team will keep you posted for more new features of upcoming Java EE8 and introduces enhancements to GlassFish Server Open Source Edition.

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