If you want the bytecode instructions themselves, use TraceClassVisitor. If you want the ASM code to generate these bytecode
instructions, use ASMifierClassVisitor. Both classes provide a "main" method to allow them to be called from the command line,
passing your fully qualified class name as a parameter. Example:

java -classpath "asm.jar;asm-util.jar;yourjar.jar" org.objectweb.asm.util.ASMifierClassVisitor org.domain.package.YourClass

or

java -classpath "asm.jar;asm-util.jar" org.objectweb.asm.util.ASMifierClassVisitor org/domain/package/YourClass.class

Another, much easier method, if you are using Eclipse, is to use the "Bytecode Outline" plugin.
Artiom_2008