Google Protocol Buffers，如何处理多种消息类型？ [英] Google Protocol Buffers, how to handle multiple message-Types?

问题描述

是否可以获取序列化协议缓冲区消息的类型？

Is it possible to get the Type of the serialized Protocol Buffer message?

我有这个例子

option java_outer_classname="ProtoUser";

message User {
    required int32  id = 1; 
    required string name = 2;
    required string firstname = 3;
    required string lastname = 4;
    required string ssn= 5; 
}

message Address {
    required int32 id = 1;
    required string country = 2 [default = "US"];; 
    optional string state = 3;
    optional string city = 4;
    optional string street = 5;
    optional string zip = 6;
}

在Java中我有这段代码

In Java I have this code

Address addr = ProtoUser.Address.newBuilder().setCity("Weston").setCountry("USA").setId(1).setState("FL").setStreet("123 Lakeshore").setZip("90210")
            .build();

    User user = ProtoUser.User.newBuilder().setId(1).setFirstname("Luis").setLastname("Atencio").setName("luisat").setSsn("555-555-5555").build();

if(....){
    FileOutputStream output = new FileOutputStream("out1.ser");
    user.writeTo(output);
    output.close();
}else{
    FileOutputStream output = new FileOutputStream("out1.ser");
    addr.writeTo(output);
    output.close();
}

现在，我可以确定文件是包含地址还是用户？处理多个消息类型的常用方法是什么？如何确定收到的消息类型？

Now, can I determine if the file contains a Address or a User? What is the common way to handle multiple Message-Types? How can I determine which Message-Type I have received?

推荐答案

我们无法确定该文件是包含地址还是用户。因为数据中没有编码类型信息。

We cannot determine if the file contains a Address or a User. Because there is not type information encoded in the data.

要处理多个消息类型，您可以使用以下元数据：

To handle multiple Message-Types, you can use meta data like:

• 文件名扩展名


• HTTP中的标题


• 帧基流协议中的特定帧头


• ...

• Extension of the filename
• Headers in HTTP
• Specific frame header in frame base stream protocol
• ...

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