This » PECL extension is not bundled with PHP.
In PHP 4 this PECL extensions source can be found in the ext/ directory within the PHP source or at the PECL link above. In order to use these functions you must compile PHP with Java support by using the --with-java[=DIR] where DIR points to the base install directory of your JDK. This extension can only be built as a shared extension. Additional build instructions can be found in php-src/ext/java/README.
Windows users will enable php_java.dll inside of php.ini in order to use these functions. In PHP 4 this DLL resides in the extensions/ directory within the PHP Windows binaries download. A DLL for this PECL extension is currently unavailable. See also the building on Windows section.
Note: In order to enable this module on a Windows environment with PHP <= 4.0.6, you must make jvm.dll available to your systems PATH. No additional DLL is needed for PHP versions > 4.0.6.