ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(byteArrayOutputStream);

        int size = byteArrayOutputStream.size();

        System.out.println("写入之前为:" + size);

        outputStreamWriter.write("我是一个魔鬼");

//        outputStreamWriter.flush();

//        outputStreamWriter.close();

        int size1 = byteArrayOutputStream.size();

        System.out.println("写入之后为:" + size1);