gistfile1.java

public class AvroJsonEncoder extends JsonEncoder {
  private Parser parser;
  private JsonGenerator out;

  private static Field parserField;
  static {
    try {
      parserField = JsonEncoder.class.getDeclaredField("parser");
      parserField.setAccessible(true);
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

  public AvroJsonEncoder(Schema sc, JsonGenerator out) throws IOException {
    super(sc, out);
    this.out = out;
    try {
      parser = (Parser) parserField.get(this);
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

  @Override
  public void writeIndex(int unionIndex) throws IOException {
    parser.advance(Symbol.UNION);
    Symbol.Alternative top = (Symbol.Alternative) parser.popSymbol();
    Symbol symbol = top.getSymbol(unionIndex);
    if (symbol != Symbol.NULL &&
            (top.labels.length != 2 || (!top.labels[0].equals("null") && !top.labels[1].equals("null")))) {
      out.writeStartObject();
      out.writeFieldName(top.getLabel(unionIndex));
      parser.pushSymbol(Symbol.UNION_END);
    }
    parser.pushSymbol(symbol);
  }
}