java properties to json

Question

Is there an easy way to convert properties with dot notation to json

I.E

server.host=foo.bar
server.port=1234

TO

{
 "server": {
    "host": "foo.bar",
    "port": 1234
  }
} 

Answer 1

Not the easy way, but I managed to do that using Gson library. The result will be in the jsonBundle String. Here we getting the properties or bundles in this case:

final ResourceBundle bundle = ResourceBundle.getBundle("messages");
final Map<String, String> bundleMap = resourceBundleToMap(bundle);

final Type mapType = new TypeToken<Map<String, String>>(){}.getType();

final String jsonBundle = new GsonBuilder()
        .registerTypeAdapter(mapType, new BundleMapSerializer())
        .create()
        .toJson(bundleMap, mapType);

For this implementation ResourceBundle have to be converted to Map containing String as a key and String as a value.

private static Map<String, String> resourceBundleToMap(final ResourceBundle bundle) {
    final Map<String, String> bundleMap = new HashMap<>();

    for (String key: bundle.keySet()) {
        final String value = bundle.getString(key);

        bundleMap.put(key, value);
    }

    return bundleMap;
}

I had to create custom JSONSerializer using Gson for Map<String, String>:

public class BundleMapSerializer implements JsonSerializer<Map<String, String>> {

    private static final Logger LOGGER = LoggerFactory.getLogger(BundleMapSerializer.class);

    @Override
    public JsonElement serialize(final Map<String, String> bundleMap, final Type typeOfSrc, final JsonSerializationContext context) {
        final JsonObject resultJson =  new JsonObject();

        for (final String key: bundleMap.keySet()) {
            try {
                createFromBundleKey(resultJson, key, bundleMap.get(key));
            } catch (final IOException e) {
                LOGGER.error("Bundle map serialization exception: ", e);
            }
        }

        return resultJson;
    }
}

And here is the main logic of creating JSON:

public static JsonObject createFromBundleKey(final JsonObject resultJson, final String key, final String value) throws IOException {
    if (!key.contains(".")) {
        resultJson.addProperty(key, value);

        return resultJson;
    }

    final String currentKey = firstKey(key);
    if (currentKey != null) {
        final String subRightKey = key.substring(currentKey.length() + 1, key.length());
        final JsonObject childJson = getJsonIfExists(resultJson, currentKey);

        resultJson.add(currentKey, createFromBundleKey(childJson, subRightKey, value));
    }

    return resultJson;
}

    private static String firstKey(final String fullKey) {
        final String[] splittedKey = fullKey.split("\\.");

        return (splittedKey.length != 0) ? splittedKey[0] : fullKey;
    }

    private static JsonObject getJsonIfExists(final JsonObject parent, final String key) {
        if (parent == null) {
            LOGGER.warn("Parent json parameter is null!");
            return null;
        }

        if (parent.get(key) != null && !(parent.get(key) instanceof JsonObject)) {
            throw new IllegalArgumentException("Invalid key \'" + key + "\' for parent: " + parent + "\nKey can not be JSON object and property or array in one time");
        }

        if (parent.getAsJsonObject(key) != null) {
            return parent.getAsJsonObject(key);
        } else {
            return new JsonObject();
        }
   }

In the end, if there were a key person.name.firstname with value John, it will be converted to such JSON:

{
     "person" : {
         "name" : {
             "firstname" : "John"
         }
     }
}

Hope this will help :)

Answer 2

Using lightbend config java library (https://github.com/lightbend/config)

String toHierarchicalJsonString(Properties props) {
  com.typesafe.config.Config config = com.typesafe.config.ConfigFactory.parseProperties(props);
  return config.root().render(com.typesafe.config.ConfigRenderOptions.concise());
}

Answer 3

It is pretty easy, download and add to your lib: https://code.google.com/p/google-gson/

Gson gsonObj = new Gson();
String strJson =  gsonObj.toJson(yourObject);

Answer 4

You can try with https://github.com/mikolajmitura/java-properties-to-json

You can generate Json from:

• from Java properties (java.util.Properties)
• from Map (import java.util.Map) -> Map<String,String>
• from Map (import java.util.Map) -> Map<String,Object>
• from InputStream with properties (java.io.InputStream)
• from given file localization with properties
• from File with properties (java.io.File)

code example:

import pl.jalokim.propertiestojson.util.PropertiesToJsonConverter;

...

Properties properties = ....;
String jsonFromProperties = new PropertiesToJsonConverter().convertToJson(properties);

InputStream inputStream = ....;
String jsonFromInputStream = new PropertiesToJsonConverter().convertToJson(inputStream);

Map<String,String> mapProperties = ....;
String jsonFromInputProperties = new PropertiesToJsonConverter().convertToJson(mapProperties);

Map<String, Object> valuesAsObjectMap = ....;
String jsonFromProperties2 = new PropertiesToJsonConverter().convertFromValuesAsObjectMap(valuesAsObjectMap);

String jsonFromFilePath = new PropertiesToJsonConverter().convertPropertiesFromFileToJson("/home/user/file.properties");

String jsonFromFile = new PropertiesToJsonConverter().convertPropertiesFromFileToJson(new File("/home/user/file.properties"));

maven dependency:

      <dependency>
          <groupId>pl.jalokim.propertiestojson</groupId>
          <artifactId>java-properties-to-json</artifactId>
          <version>5.1.0</version>
      </dependency>

dependency required minimum java 8.

more example of uses on https://github.com/mikolajmitura/java-properties-to-json

Answer 5

I didn't want any dependency on gson and I wanted to return a hierarchical json from a Spring controller so a deep Map was enough for me.

This works for me, just loop over all your keys and pass in an empty map.

void recurseCreateMaps(Map<String, Object> currentMap, String key, String value) {
    if (key.contains(".")) {
        String currentKey = key.split("\\.")[0];

        Map<String, Object> deeperMap;

        if (currentMap.get(currentKey) instanceof Map) {
            deeperMap = (Map<String, Object>) currentMap.get(currentKey);
        } else {
            deeperMap = new HashMap<>();
            currentMap.put(currentKey, deeperMap);
        }

        recurseCreateMaps(deeperMap, key.substring(key.indexOf('.') + 1), value);
    } else {
        currentMap.put(key, value);
    }
}

Answer 6

Look at this https://github.com/nzakas/props2js. You can use it manually or fork and use in your project.

Answer 7

A little bit recursion and Gson :)

public void run() throws IOException {

    Properties properties = ...;

    Map<String, Object> map = new TreeMap<>();

    for (Object key : properties.keySet()) {
        List<String> keyList = Arrays.asList(((String) key).split("\\."));
        Map<String, Object> valueMap = createTree(keyList, map);
        String value = properties.getProperty((String) key);
        value = StringEscapeUtils.unescapeHtml(value);
        valueMap.put(keyList.get(keyList.size() - 1), value);
    }

    Gson gson = new GsonBuilder().setPrettyPrinting().create();
    String json = gson.toJson(map);

    System.out.println("Ready, converts " + properties.size() + " entries.");
}

@SuppressWarnings("unchecked")
private Map<String, Object> createTree(List<String> keys, Map<String, Object> map) {
    Map<String, Object> valueMap = (Map<String, Object>) map.get(keys.get(0));
    if (valueMap == null) {
        valueMap = new HashMap<String, Object>();
    }
    map.put(keys.get(0), valueMap);
    Map<String, Object> out = valueMap;
    if (keys.size() > 2) {
        out = createTree(keys.subList(1, keys.size()), valueMap);
    }
    return out;
}

Answer 8

just use org.json.JSONObject constructor that receives a Map (which Properties extends):

JSONObject jsonProps = new JSONObject(properties);
jsonProps.toString();

If you don't already have the properties loaded you can do that from a file

Properties properties= new Properties();
File file = new File("/path/to/test.properties");
FileInputStream fileInput = new FileInputStream(file);
properties.load(fileInput);

If you want to do the reverse, and read a json string into a prop file you can use com.fasterxml.jackson.databind.ObjectMapper:

HashMap<String,String> result = new ObjectMapper().readValue(jsonPropString, HashMap.class);
Properties props = new Properties();
props.putAll(result);

Answer 9

Personally I used this dependency:

<dependency>
  <groupId>com.fasterxml.jackson.dataformat</groupId>
  <artifactId>jackson-dataformat-properties</artifactId> 
  <version>2.10.2</version>
  <scope>compile</scope>
</dependency>

private static JavaPropsMapper javaPropsMapper = JavaPropsMapper.builder().build();
final JsonNode request = javaPropsMapper.readPropertiesAs(parameters, JsonNode.class);

Try to use schema validation to avoid possible issues in you mapping.

Although, with a simple object mapper it is possible also

Properties properties = new Properties();
properties.put("array", new int[] {1,2,3});
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.writeValueAsString(parameters);

Output

{"fullname":["Foo","Bar"]}

Answer 10

Try reading this http://www.oracle.com/technetwork/articles/java/json-1973242.html, you will find several class to work with json.

I guess that retrieving the json from a local file, inner resource in the jar, or in another location specificable by an URL and the just read it with a JsonReader get the job dones.

---

This is a snipped from the reference site posted before.

 URL url = new URL("https://graph.facebook.com/search?q=java&type=post");
 try (InputStream is = url.openStream();
      JsonReader rdr = Json.createReader(is)) {

      JsonObject obj = rdr.readObject();
      // from this line forward you got what you want :D

     }
 }

Hope it helps!