Gson Deserialization error: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING

Question

I've seen the many questions on this topic, but can't seem to find the solution to my problem.

I'm getting a deserialization error:

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 3384

when deserializing my RoutingTable clas specifically, decerialization works perfectly well for everything else. I've uploaded the serialized json data here: http://jsonfiddle.net/bx0ga

Class to serialize:

public class RoutingTable
{
    private transient final Node localNode;  // The current node
    private final KadBucket[] buckets;


    {
        buckets = new KadBucket[NodeId.ID_LENGTH];
    }
    // Methods....
}

KadBucket class:

public class KadBucket implements Bucket
{
    private final int depth;
    private final Map<NodeId, Node> nodes;

    {
        nodes = new HashMap<>();
    }
    // methods and so on
}

Serialization code: i have a serialization class that handles serialization using generics:

public class JsonSerializer<T> implements KadSerializer<T>
{
    private final Gson gson;
    {
        gson = new Gson();
    }

    @Override
    public void write(T data, DataOutputStream out) throws IOException
    {
        try (JsonWriter writer = new JsonWriter(new OutputStreamWriter(out)))
        {
            writer.beginArray();

            /* Store the content type */
            gson.toJson(data.getClass().getName(), String.class, writer);

            /* Now Store the content */
            gson.toJson(data, data.getClass(), writer);

            writer.endArray();
        }
    }

    @Override
    public T read(DataInputStream in) throws IOException, ClassNotFoundException
    {
        try (DataInputStream din = new DataInputStream(in);
                JsonReader reader = new JsonReader(new InputStreamReader(in)))
        {
            reader.beginArray();

            /* Read the class name */
            String className = gson.fromJson(reader, String.class);

            /* Read and return the Content*/
            return gson.fromJson(reader, Class.forName(className));
        }
    }
}

So for serialization, I do:

// Writing to dout which is an output stream
new JsonSerializer<RoutingTable>().write(this.localNode.getRoutingTable(), dout);

// Reading from din which is an input stream
RoutingTable irtbl = new JsonSerializer<RoutingTable>().read(din);

Using this works perfectly for every other class in the system, except for routing tables.

Answer 1

RoutingTable包含临时的类变量，用于指示不应序列化字段。

Answer 2

To me it's seems like your input is not JSON object. Happened to me also once also but i don't remember exactly what was the problem but i guess it was because of space in the beginning. Look at the raw input which you are providing for deserialization and convert it into proper json object.