使用protobuf进行序列化时出错

Question

I'm trying to serialize a structure with protobuf. after many hours trying to figure out what I'm doing wrong I decided to test the google's example and it didn't worked as well

I have the following protocol from google ( https://developers.google.com/protocol-buffers/docs/javatutorial ):

package tutorial;
option java_package = "com.example.tutorial";
option java_outer_classname = "AddressBookProtos";

message Person {
    required string name = 1;
    required int32 id = 2;
    optional string email = 3;
    repeated PhoneNumber phone = 4;

    enum PhoneType {
        MOBILE = 0;
        HOME = 1;
        WORK = 2;
    }

    message PhoneNumber {
        required string number = 1;
        optional PhoneType type = 2 [default = HOME];
    }
}

message AddressBook {
    repeated Person person = 1;
}

and I'm trying to serialize it with:

Person john = Person.newBuilder()   
    .setId(1234)
    .setName("John Doe")
    .setEmail("jdoe@example.com")
    .addPhone(
        Person.PhoneNumber.newBuilder()
            .setNumber("555-4321")
            .setType(Person.PhoneType.HOME))
    .build();

byte[] serialized = john.toByteArray();

and I get "java.lang.UnsupportedOperationException: This is supposed to be overridden by subclasses."

Thanks;

Answer 1

As Marc said, A mismatch in Protocol Buffer versions will give you this exact message. In particular if

• The .proto definition is converted to java using the 2.4.3 (or earlier) protoc.exe
• You use the 2.5.0 protobuffers library

you will get this message in many methods (eg getParserForType, getUnknownFields) of class GeneratedMessage . There are no doubt other potential mismatch's that will cause this error

---

With protocol buffers 2.5.0 it is essential you regenerate all java classes with the 2.5.0 version of protoc (or on windows protoc.exe).

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If you do the reverse - run code generated by protoc version 2.5 with the libraries for protocol buffers version 2.4 . You will get the following message

java.lang.VerifyError: class xxx.xxx.xx.. 
overrides final method getUnknownFields.()Lcom/google/protobuf/UnknownFieldSet;