Lista de contribuições gravadas em Servidor Web Java. Carregar somente contribuições de um CPF?

Busca Lista private void buscarListaContribs() { showProgressDialog(); contribs.clear(); JsonArrayRequest request = new UTF8ParseJson(Constantes.URL_WS_BASE + "contribs", new Response.Listener() { public void onResponse(JSONArray response) { Type type = new TypeToken<List>() { }.getType(); List contribs = new Gson().fromJson(response.toString(), type);

            ListaMembroActivity.this.contribs.addAll(contribs);

            customMembroAdapter.notifyDataSetChanged();
               progressDialog.dismiss();
             }
    },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.e("Erro no carregamento de Dízimos/Oferta", error);
                    Toast.makeText(ListaMembroActivity. this,"Erro na listagem de Dizimo/Oferta", Toast.LENGTH_SHORT).show();
                }
            }
    );
    IgrejaApp.getInstance().addToRequestQueue(request);
}

public class CustomContribAdapter extends BaseAdapter {

private final Activity activity;
private final List<Contrib> contribs;
private ContribListAdapterListener contribListAdapterListener;
private LayoutInflater inflater;
private ImageLoader imageLoader = IgrejaApp.getInstance().getImageLoader();

public CustomContribAdapter(
    final Activity activity,
    final List<Contrib> contribs,
    final ContribListAdapterListener contribListAdapterListener) {
       this.activity = activity;
       this.contribs = contribs;
       this.contribListAdapterListener = contribListAdapterListener;
}
@Override
public int getCount() {
    return contribs.size();
}
@Override
public Object getItem(int position) {
    return contribs.get(position);
}
@Override
public long getItemId(int position) {
    return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if (inflater == null) {
        inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
    if (convertView == null) {
        convertView = inflater.inflate(R.layout.linha_produto3, null);
    }
    NetworkImageView imgContrib = convertView.findViewById(R.id.imgContrib);
    TextView txtTitulo = (TextView) convertView.findViewById(R.id.txtTitulo);
    TextView txtNome = (TextView) convertView.findViewById(R.id.txtNome);
    TextView txtPreco = (TextView) convertView.findViewById(R.id.txtPreco);
    TextView txtDat1 = (TextView) convertView.findViewById(R.id.txtDat1);
    Button btnDetalhes = (Button) convertView.findViewById(R.id.btnDetalhes);

    final Contrib contrib = contribs.get(position);

    imgContrib.setImageUrl(Constantes.URL_WS_BASE + contrib.getUrl(), imageLoader);
    txtTitulo.setText(contrib.getTitulo());
    txtNome.setText(contrib.getNome());
    txtDat1.setText(contrib.getDat1());
     String valor = NumberFormat.getCurrencyInstance().format(contrib.getValor1());
    txtPreco.setText(valor);

  }

Servidor WEB

@GET @Path("contribs") @Produces(MediaType.APPLICATION_JSON + ";charset=utf-8") public List listContribs() { try { return contribDAO.listarContribs(); } catch (Exception e) { e.printStackTrace(); return null; } }

public List listarContribs() { String sql = "SELECT * FROM tb_contrib where cpf='"+a3+"'"; List retorno = new ArrayList();

    PreparedStatement pst = Conexao.getPreparedStatement(sql);
    try {

        ResultSet res = pst.executeQuery();
        while(res.next())
        {
             Contrib item = new Contrib();
             item.setNome(res.getString("nome"));
             item.setCpf(res.getString("cpf"));
             item.setValor1(res.getBigDecimal("valor1"));
             item.setTitulo(res.getString("titulo"));
             item.setDat1(res.getString("dat1"));
             item.setDat3(res.getInt("dat3"));
             retorno.add(item);
               }
          } catch (SQLException ex) {
        Logger.getLogger(ContribDAO.class.getName()).log(Level.SEVERE, null, ex);

          }
   return retorno;
  }

`