我在这里参加聚会有点晚，但是下面的实现包括其他答案中缺少的一些优化，并且在输入64MB后不会失败（尽管它仍然对每个单独的消息强制执行64MB的限制，只是对整个消息流没有限制））。
（我是C ++和Java protobuf库的作者，但我不再在Google上工作。很抱歉，此代码从未将其添加到官方lib中。如果有的话，它的样子。）
bool writeDelimitedTo( const google::protobuf::MessageLite& message, google::protobuf::io::ZeroCopyOutputStream* rawOutput) { // We create a new pred stream for each message. Don't worry, this is fast. google::protobuf::io::CodedOutputStream output(rawOutput); // Write the size. const int size = message.ByteSize(); output.WriteVarint32(size); uint8_t* buffer = output.GetDirectBufferForNBytesAndAdvance(size); if (buffer != NULL) { // Optimization: The message fits in one buffer, so use the faster // direct-to-array serialization path. message.SerializeWithCachedSizesToArray(buffer); } else { // Slightly-slower path when the message is multiple buffers. message.SerializeWithCachedSizes(&output); if (output.HadError()) return false; } return true;}bool readDelimitedFrom( google::protobuf::io::ZeroCopyInputStream* rawInput, google::protobuf::MessageLite* message) { // We create a new pred stream for each message. Don't worry, this is fast, // and it makes sure the 64MB total size limit is imposed per-message rather // than on the whole stream. (See the CodedInputStream interface for more // info on this limit.) google::protobuf::io::CodedInputStream input(rawInput); // Read the size. uint32_t size; if (!input.ReadVarint32(&size)) return false; // Tell the stream not to read beyond that size. google::protobuf::io::CodedInputStream::Limit limit = input.PushLimit(size); // Parse the message. if (!message->MergeFromCodedStream(&input)) return false; if (!input.ConsumedEntireMessage()) return false; // Release the limit. input.PopLimit(limit); return true;}
