IO之BufferedOutputStream

Question

当使用BufferedOutputStream为其做缓冲的时候，dataOutputStream对象的size为0，而不使用BufferedOutputStream做缓冲时，dataOutputStream值获取正常？ String string = "数据类型"; double d = 2.3; long p = 10L; byte[] byteArray = null; ByteArrayOutputStream bout = new ByteArrayOutputStream(); **//DataOutputStream dataOutputStream = new DataOutputStream(new BufferedOutputStream(bout));** DataOutputStream dataOutputStream = new DataOutputStream(bout); try { dataOutputStream.writeUTF(string); dataOutputStream.writeLong(p); dataOutputStream.writeDouble(d); **System.out.println(dataOutputStream.size());** byteArray = bout.toByteArray(); dataOutputStream.flush(); dataOutputStream.close(); bout.close(); } catch (IOException e) { e.printStackTrace(); } 为什么这样可以: DataInputStream dataInputStream = new DataInputStream(new BufferedInputStream(new ByteArrayInputStream(bs))); try { System.out.println(dataInputStream.readUTF()); System.out.println(dataInputStream.readLong()); System.out.println(dataInputStream.readDouble()); } catch (IOException e) { e.printStackTrace(); }

Answer 1

要dataOutputStream.flush();在先，System.out.println(dataOutputStream.size());在后