Javassist

Javassist (Java programming assistant) makes bytecode engineering simple. It is a class library for editing bytecode in Java; it enables Java programs to define a new class at runtime and to modify a given class file when the JVM loads it.

The most significant class of this package is CtClass. See the description of this class first.

To know the version number of this package, type the following command:

java -jar javassist.jar

It prints the version number on the console.

This package provides low-level API for editing a raw class file. It allows the users to read and modify a constant pool entry, a single bytecode instruction, and so on.

The users of this package must know the specifications of class file and Java bytecode. For more details, read this book:

Tim Lindholm and Frank Yellin, "The Java Virtual Machine Specification 2nd Ed.", Addison-Wesley, 1999.

This package provides low-level API for editing annotations attributes.

This package contains the classes for modifying a method body. See ExprEditor (expression editor) for more details.

This package includes support classes that may be required by classes modified with Javassist. Note that most of the modified classes do not require these support classes. See the documentation of every support class to know which kind of modification needs a support class.

A custom class pool for several JBoss products. It is not part of Javassist.

(also recently known as interceptors or AOP?)

This package enables a metaobject to trap method calls and field accesses on a regular Java object. It provides a class Reflection, which is a main module for implementing runtime behavioral reflection. It also provides a class Loader and Compiler as utilities for dynamically or statically translating a regular class into a reflective class.

An instance of the reflective class is associated with a runtime metaobject and a runtime class metaobject, which control the behavior of that instance. The runtime metaobject is created for every (base-level) instance but the runtime class metaobject is created for every (base-level) class. Metaobject is the root class of the runtime metaobject and ClassMetaobject is the root class of the runtime class metaobject.

This package is provided as a sample implementation of the reflection mechanism with Javassist. All the programs in this package uses only the regular Javassist API; they never call any hidden methods.

The most significant class in this package is Reflection. See the description of this class first.

This package enables applets to access remote objects running on the web server with regular Java syntax. It is provided as a sample implementation with Javassist. All the programs in this package uses only the regular Javassist API; they never call any hidden methods.

The most significant class of this package is ObjectImporter. See the description of this class first.

This package provides a simple web server for sample packages.

The preprocessor for running Javassist at compile time. The produced class files are saved on a local disk.

This package is provided as a sample implementation of the preprocessor using Javassist. All the programs in this package uses only the regular Javassist API; they never call any hidden methods.