[ASM] introduction and use of bytecode operation classwriter class

0. summary

This chapter video ： https://www.bilibili.com/video/BV1ww411o7pF/?spm_id_from=pageDriver

stay asm.jar In file ,- Includes 30 Multiple classes , We will introduce 10 Classes . that , The rest 20 Multiple classes , Why not introduce ? Because the rest 20 Multiple main functions ” auxiliary ” The role of , They tend to work behind the scenes ”; and ” On the stage " It belongs to that 10 Classes .

stay “ Chapter two ” among , We will mainly introduce from “ nothing “ To “ Yes “ Generate a new class , It will involve ClassVisitor.ClassWriter 、FieldVisitor 、FieldWriter 、MethodVisitor 、MethodWriter 、Label and Opcodes class .

stay “ The third chapter ” among , We will mainly introduce the modification “ Beauty that already exists ”, Change the content , It will involve ClassReader and Type class .

Here 10 Among the three classes , The most important are the three classes , namely ClassReader、ClassVisitor.ClassWriter class . The relationship between these three classes , It can be described as the following figure :

1. ClassWriter

1.1 class info

First Department