java协议缓冲区：从文件中读取所有序列化消息

Question

我正在尝试序列化和反序列化protobuf消息。按照documentation中的例子，我写道：

ByteArrayOutputStream out = new ByteArrayOutputStream(...);
ArrayList<AddressBookProtos.Person> messages = ...;
for (int i = 0; i < messages.size; i++){
  messages.writeTo(out);
  out.flush();
}
out.close();

当我读回这些信息时，我希望写下：

ByteArrayInputStream in = new ByteArrayInputStream(...);
ArrayList<AddressBookProtos.Person> messages = new ArrayList<...>();
while (in.available() > 0) {
   messages.add(AddressBookProtos.Person.parseFrom(in));
}

然而，我总是只得到一个结果。其他结果都到哪里去了

Answer 1

您必须使用^{}/parseDelimitedFrom或实现自己的基于分隔符的解决方案

根据javadoc：

... writes the size of the message as a varint before writing the data. This allows more data to be written to the stream after the message without the need to delimit the message data yourself. Use MessageLite.Builder.mergeDelimitedFrom(InputStream) (or the static method YourMessageType.parseDelimitedFrom(InputStream)) to parse messages written by this method.