is = new FileInputStream(classFile);
ClassReader classReader = new ClassReader(is);
ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);
ClassVisitor classVisitor = new TraceClassAdapter(Opcodes.ASM5, classWriter);
classReader.accept(classVisitor, ClassReader.EXPAND_FRAMES);
is.close();
if (output.isDirectory()) {
os = new FileOutputStream(changedFileOutput);
} else {
os = new FileOutputStream(output);
}
os.write(classWriter.toByteArray());
os.close();
classReader用来读取来自inputstream的class字节码，并在遍历到类和方法时分别调用到visit和visitMethod方法，参数为解析出的信息
graph LR
FileInputStream-->classReader
classReader-->ClassVisitor
ClassVisitor-->ClassWriter
ClassWriter-->FileOutputStream
@Override
public MethodVisitor visitMethod(int access, String name, String desc,
String signature, String[] exceptions) {
在方法开始处插桩AppMethodBeat.i(methodId)方法
@Override
protected void onMethodEnter() {
TraceMethod traceMethod = collectedMethodMap.get(methodName);
if (traceMethod != null) {
traceMethodCount.incrementAndGet();
mv.visitLdcInsn(traceMethod.id);
mv.visitMethodInsn(INVOKESTATIC, TraceBuildConstants.MATRIX_TRACE_CLASS, "i", "(I)V", false);
}
}