content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.calcite.avatica.remote;
  
  import org.apache.calcite.avatica.metrics.MetricsSystem;
  import org.apache.calcite.avatica.metrics.Timer;
  import org.apache.calcite.avatica.metrics.Timer.Context;
  import org.apache.calcite.avatica.remote.Service.Request;
  import org.apache.calcite.avatica.remote.Service.Response;
  
  import com.fasterxml.jackson.databind.ObjectMapper;
  
  import java.io.IOException;
  import java.io.StringWriter;
  
  /**
   * Implementation of {@link org.apache.calcite.avatica.remote.Handler}
   * that decodes JSON requests, sends them to a {@link Service},
   * and encodes the responses into JSON.
   *
   * @see org.apache.calcite.avatica.remote.JsonService
   */
  public class JsonHandler extends AbstractHandler<String> {
  
    protected static final ObjectMapper MAPPER = JsonService.MAPPER;
  
    final MetricsSystem metrics;
    final Timer serializationTimer;
  
    public JsonHandler(Service service, MetricsSystem metrics) {
      super(service);
      this.metrics = metrics;
      this.serializationTimer = this.metrics.getTimer(
          MetricsHelper.concat(JsonHandler.class, HANDLER_SERIALIZATION_METRICS_NAME));
    }
  
    public HandlerResponse<String> apply(String jsonRequest) {
      return super.apply(jsonRequest);
    }
  
    @Override Request decode(String request) throws IOException {
      try (Context ctx = serializationTimer.start()) {
        return MAPPER.readValue(request, Service.Request.class);
      }
    }
  
    /**
     * Serializes the provided object as JSON.
     *
     * @param response The object to serialize.
     * @return A JSON string.
     */
    @Override String encode(Response response) throws IOException {
      try (Context ctx = serializationTimer.start()) {
        final StringWriter w = new StringWriter();
        MAPPER.writeValue(w, response);
        return w.toString();
      }
    }
  }
  
  // End JsonHandler.java
  