Install @Java on Microsoft Windows

These are a few instructions to install @Java on Microsoft Windows.

Software requirements

In order to get the package works, you need to have the following packages properly installed and configured.

You also have to make sure that your JAVA_HOME environment variable is set.

Getting @Java package installed

Download the @Java archive at the following link:

and unzip it in the location where you want to install it. It will create three directories:

Contains the atjavac compiler script
Contains the @Java jar libraries
Contains the @Java API documentation

It may be useful to add the bin directory to your PATH environment variable.

Patch the Java class library

In order to patch the Java class library file, you need to logon with an user that have administrative permissions.

Since @Java alters some reflective mechanism of the language, we need to modify some standard classes contained in the rt.jar file. The rt.jar file is located in the $JAVA_HOME\jre\lib\ directory. It is suggested to make a copy of the original file before proceeding.

Go to an empty directory and copy the rt.jar there.

copy %JAVA_HOME%\jre\lib\rt.jar .

Extract the Field.class, Method.class, Method.class files with the following command:

jar xf rt.jar java\lang\reflect\Method.class
java\lang\reflect\Constructor.class java\lang\reflect\Field.class

Extract the content of the atjavac.jar and the atjava.jar library file in the current directory


jar xf ATJAVA_INSTALLATION_DIR\atjavac.jar

Extract the content of the bcel.jar library file in the current directory

jar xf BCEL_INSTALLATION_DIR\bcel-5.2.jar

Apply the aspects:

ajc -inpath java -aspectpath atjava\lang\annotation -d .

Update the rt.jar archive

jar uf rt.jar java atjava atjavac org

Move the rt.jar in its original location

move rt.jar %JAVA_HOME%\jre\lib

If everything went fine, you can now compile @Java enhanched programs with the atjavac compiler, and execute them with the usual java invocation.

Walter Cazzola



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