Protobuf getAllFields() not working as expected

问题

I need to parse protobuf messages sent by third party and process those. A part where I am facing an issue in accessing fields looks like following:

ext {\n  is_foo: NO\n  is_bar: false\n  
12: \"fgyhcbho-4594-34545-gbvj\"\n  13: 0\n }

I am mainly interested in accessing the value of the field name "12". However, getAllFields().entrySet() returns only 2 entries - is_foo and is_bar . So I am unable to get the value "fgyhcbho-4594-34545-gbvj" of the field "12".

Following is a part of my .proto file which I compiled using protobuf(v2.6) compiler to generate .java file:

message Ext {
    optional bool is_foor = 1;      
    optional bool is_bar = 2;  
    optional string uid = 12;  
    optional int32 did = 13;  
 }

My .java file contains method hasUid() and getUid(). But the protobuf message I receive contains field "12" and not "uid". So when I try to deserialize to Java, it just does not contain that field and no unknown fields either.

Below is the code snippet I am using:

if (this.protoReq.getExt() != null) {
        for (Map.Entry<FieldDescriptor, Object> entry : this.protoReq.getExt().getAllFields().entrySet()) {
            FieldDescriptor field = entry.getKey();
            if (field.getName().equals("12")) {
                Object value = entry.getValue();
                if (value != null) {
                   //do something
                }
                break;
            }
        }
    }

Am I missing something? Is there any other way to access it ? Any help is appreciated. Thank you.

回答1:

When you see fields with numeric labels, it means that the field is an unknown field -- the number seen on the wire doesn't match any field name defined in the .proto file.

getAllFields() only returns known fields, because it returns a descriptor->value map, and descriptors only exist for known fields.

To read unknown fields, you need to call message.getUnknownFields(), which returns an UnknownFieldSet. That object maps unknown field numbers to values.

来源：https://stackoverflow.com/questions/41131076/protobuf-getallfields-not-working-as-expected

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java

protocol-buffers