如何解决＆＃34; com.google.protobuf.InvalidProtocolBufferException：找不到字段＆＃34;从JsonFormat.parser（）抛出。合并（...）？

Question

我有2个Protobuf模型：

User

package demo;

option java_package = "com.stackoverflow.question";
option java_outer_classname = "UserModel";

message User {

    message UserHeader {
        required int64 userId = 1;
    }

    required UserHeader header = 1;

    extensions 100 to 200;
}

Employee

import "person.proto";

package demo;

option java_package = "com.stackoverflow.question";
option java_outer_classname = "EmployeeModel";

extend demo.User {
    optional EmployeeDetails details = 101;
}

message EmployeeDetails {
    required string department = 1;
    repeated Skill skills = 2;
}

message Skill {
    required int64 id = 1;
    required string name = 2;
}

我可以使用JsonFormat.printer().print(...)创建模型并将其序列化为JSON：

ExtensionRegistry registry = ExtensionRegistry.newInstance();
EmployeeModel.registerAllExtensions(registry);

UserModel.User.Builder userBuilder = UserModel.User.newBuilder();
userBuilder.setHeader(UserModel.User.UserHeader.newBuilder().setUserId(1000));

EmployeeModel.EmployeeDetails.Builder employeeBuilder = EmployeeModel.EmployeeDetails.newBuilder();
employeeBuilder.setDepartment("Department 1")
               .addSkills(EmployeeModel.Skill.newBuilder()
                                             .setId(10_000)
                                             .setName("Skill 10_0000")
                                             .build())
               .addSkills(EmployeeModel.Skill.newBuilder()
                                             .setId(11_000)
                                             .setName("Skill 11_0000")
                                             .build());

userBuilder.setExtension(EmployeeModel.details, employeeBuilder.build());

final String json = JsonFormat.printer().print(userBuilder.build());

然而，将生成的JSON反序列化回Java对象失败了com.google.protobuf.InvalidProtocolBufferException: Cannot find field: details in message demo.User：

UserModel.User.Builder userBuilder2 = UserModel.User.newBuilder();

JsonFormat.parser().merge(json, userBuilder2);

似乎也没有办法将ExtensionRegistry传递给JsonFormat.parser()。

有没有办法让 Protobuf→JSON→Protobuf 序列化/反序列化链工作？

Answer 1

显然是JsonFormat的解析器does not support extensions。