JsonValues.java

package com.sf.monitor.utils;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.google.common.base.Function;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

import java.io.IOException;
import java.util.List;
import java.util.Map;

@JsonSerialize(using = JsonValues.ValuesJsonSerializer.class)
public class JsonValues {
  public Map<String, Object> values;

  public JsonValues(Map<String, Object> values) {
    this.values = values;
  }

  public static <T> JsonValues of(Map<String, T> rawValues) {
    return new JsonValues(
      Maps.transformValues(
        rawValues, new Function<T, Object>() {
          @Override
          public Object apply(T input) {
            return (Object) input;
          }
        }
      )
    );
  }

  public static <T> JsonValues of(Map<String, T> parseVals, String... keys) {
    return of(parseVals, Lists.newArrayList(keys));
  }

  public static <T> JsonValues of(Map<String, T> parseVals, List<String> keys) {
    JsonValues values = new JsonValues(Maps.<String, Object>newLinkedHashMap());
    for (String key : keys) {
      T val = parseVals.get(key);
      if (val == null) {
        values.values.put(key, "unknown");
      } else {
        values.values.put(key, val);
      }
    }
    return values;
  }

  public static Iterable<Map<String, Object>> toMaps(Iterable<JsonValues> values) {
    return Iterables.transform(
      values, new Function<JsonValues, Map<String, Object>>() {
        @Override
        public Map<String, Object> apply(JsonValues input) {
          return input.values;
        }
      }
    );
  }

  public static class ValuesJsonSerializer extends JsonSerializer<JsonValues> {
    @Override
    public void serialize(
      JsonValues value, JsonGenerator jgen, SerializerProvider provider
    ) throws IOException, JsonProcessingException {
      JsonSerializer<Object> serializer = provider.findValueSerializer(value.values.getClass(), null);
      serializer.serialize(value.values, jgen, provider);
    }
  }
}