Annotation Processing Tool (apt)
Note: The apt tool and its associated API contaiined in the pakcage com.sun.mirror have been deprecated since Java SE 7. Use the options available in the javac tool and the APIs contained in the packages javax.annotation.processing and javax.lang.model to process annotations.
The apt tool is a command-line utility for
annotation processing. It includes a set of reflective APIs and
supporting infrastructure to process program annotations (JSR 175). These
reflective APIs provide a build-time, source-based, read-only view
of program structure. They are designed to cleanly model the
Java programming language's type system
after the addition of generics (JSR 14).
The apt tool first runs annotation processors that can
produce new source code and other files. Next, apt can
cause compilation of both original and generated source files, thus
easing the development cycle.
JSR 269, also known as the Language Model API, has two basic pieces: an API that models the Java programming language, and an API for writing annotation processors. This functionality is accessed through new options to the javac command; by including JSR 269 support, javac now acts analogously to the apt command in JDK 5.