使用Javassist获取字节码的参数

Question

http://lpaste.net/338173的反汇编代码（使用javap -c）如下所示： http : //lpaste.net/338175 ，在第三列上，有200个参数作为“ sipush”的参数我是从使用javassist的类文件中获得的？

Answer 1

sipush is a bytecode which takes a single two byte argument which is a number to push onto the operand stack. In Javassist, you can iterate over all bytecode of a method via the CodeAttribute that is available from the CtMethod 's MethodInfo . In your case, it would be the first byte code, but you can check that you reached Opcode.SIPUSH . Once you iterated to this instruction you can read the 2 byte argument via the s16bitAt method from the iterator. The method takes a zero-based index. In your case, this makes the argument zero for sipush , returning 200 as a value.