Java 类org.objectweb.asm.commons.InstructionAdapter 实例源码

private void createStaticConstructor(ClassNode owner) throws UnsupportedEncodingException {
    MethodNode original = BytecodeHelper.getMethod(owner, "<clinit>", "()V");
    MethodVisitor mv = owner.visitMethod(Opcodes.ACC_STATIC, "<clinit>", "()V", null, null);
    // generate instructions
    InstructionAdapter builder = new InstructionAdapter(mv);
    builder.iconst(stringList.size());
    builder.newarray(Type.getType(String.class));
    for (int i = 0; i < stringList.size(); i++) {
        builder.dup();
        builder.iconst(i);
        builder.aconst(Base64.getEncoder().encodeToString(stringList.get(i).getBytes("UTF-8")));
        builder.astore(InstructionAdapter.OBJECT_TYPE);
    }
    builder.putstatic(unscrambleClass.name, FIELD_NAME, "[Ljava/lang/String;");
    // merge with original if it exists
    if (original != null) {
        // original should already end with RETURN
        owner.methods.remove(original);
        original.instructions.accept(builder);
    } else {
        builder.areturn(Type.VOID_TYPE);
    }
}

@Override
public int writeCLInit(String fieldName, InstructionAdapter insts, String className) {
  insts.iconst(values.size());
  insts.newarray(Type.INT_TYPE);
  int curIndex = 0;
  for (Integer value : values) {
    insts.dup();
    insts.iconst(curIndex);
    insts.iconst(value);
    insts.astore(Type.INT_TYPE);
    ++curIndex;
  }
  insts.putstatic(className, fieldName, DESC);
  // Needs up to 4 stack slots for: the array ref for the putstatic, the dup of the array ref
  // for the store, the index, and the value to store.
  return 4;
}

private static void writeStaticClassInit(
    ClassWriter classWriter,
    String className,
    Map<String, FieldInitializer> deferredInitializers) {
  MethodVisitor visitor =
      classWriter.visitMethod(
          Opcodes.ACC_STATIC, "<clinit>", "()V", null, /* signature */ null /* exceptions */);
  visitor.visitCode();
  int stackSlotsNeeded = 0;
  InstructionAdapter insts = new InstructionAdapter(visitor);
  for (Entry<String, FieldInitializer> fieldEntry : deferredInitializers.entrySet()) {
    final FieldInitializer fieldInit = fieldEntry.getValue();
    stackSlotsNeeded =
        Math.max(stackSlotsNeeded, fieldInit.writeCLInit(fieldEntry.getKey(), insts, className));
  }
  insts.areturn(Type.VOID_TYPE);
  visitor.visitMaxs(stackSlotsNeeded, 0);
  visitor.visitEnd();
}

@Override
public int writeCLInit(String fieldName, InstructionAdapter insts, String className) {
  insts.iconst(value);
  insts.putstatic(className, fieldName, DESC);
  // Just needs one stack slot for the iconst.
  return 1;
}

/**
 * Write the bytecode for the clinit portion of initializer.
 * @return the number of stack slots needed for the code.
 */
int writeCLInit(String fieldName, InstructionAdapter insts, String className);