ASM provides a simple library that exposes the internal aggregate components of a given Java class through its
visitor oriented API. ASM also provides, on top of this visitor API, a tree API that represents classes as object constructs. Both APIs can be used for modifying the binary bytecode, as well as generating new bytecode (via injection of new code into the existing code, or through generation of new classes altogether.) The ASM library has been used in several diverse applications, such as: ;Performance and Profiling :Instrumentation calls that capture performance metrics can be injected into Java class binaries to examine memory/coverage data. (For example, injecting instrumentation at entry/exit points.) ;Implementation of New Language Semantics :For example,
Groovy uses ASM to generate its bytecode. Also,
Aspect-Oriented additions to the Java language have been implemented by using ASM to decompose class structures for point-cut identification, and then again when reconstituting the class by injecting aspect-related code back into the binary. (See:
AspectWerkz)
Invokedynamic Since version 3.2,
ASM has added support for the new invokedynamic code, which allows method invocation relying on dynamic
type checking on the latest
JDK 7 binaries, thus easing support for
dynamically typed languages.{{cite web == Release history ==