Java Properties file to JSON using Jackson

Question

I would like to convert a Java Properties file into JSON with nested objects. I followed an example I found here but I can't get it to work.

For example, given:

objectA.version=1.0
objectA.hostname=192.168.0.11
objectA.port=9989
objectB.hostname=10.0.2.15
objectB.port=9998

I want:

{ 
  “objectA” : {
             "version” : "1.0"
             "host” : “192.168.0.11”,
             "port" : 9989
           },
  “objectB” : {
             "host” : “10.0.2.15”,
             "port" : 9998
           }
}

This is what I have so far:

static class Endpoint
{
    @JsonProperty("objectA")
    public ObjectA objectA;

    @JsonProperty("objectB")
    public ObjectB objectB;

}
static class ObjectA
{
    public String hostname;
    public String port;
    public String version;
}

static class ObjectB
{
    public String hostname;
    public String port;
}

try (InputStream input = getClass().getClassLoader().getResourceAsStream("file.properties"))
{
    JavaPropsMapper mapper = new JavaPropsMapper();
    Endpoint host = mapper.readValue(input, Endpoint.class);
    String asText = mapper.writeValueAsString(host);
    System.out.println(asText);
}

The output looks like this:

objectA.version=1.0
objectA.hostname=192.168.0.11
objectA.port=9989
objectB.hostname=10.0.2.15
objectB.port=9998

Answer 1

I figured it out.

try (InputStream input = getClass().getClassLoader().getResourceAsStream("file.properties"))
{
    JavaPropsMapper mapper = new JavaPropsMapper();
    Endpoint host = mapper.readValue(input, Endpoint.class);
    // String asText = mapper.writeValueAsString(host);

    // add this
    ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
    String asText = ow.writeValueAsString(host);
    // 

    System.out.println(asText);
}

Answer 2

Not sure if the OP needs an interim object OR if he just wants to get from a props file to a JSON representation of it. If it is the latter then it's easier to just use the databind ObjectNode class as the interim. Eg

try (InputStream input = new FileInputStream("path_to.properties")) {

    JavaPropsMapper mapper = new JavaPropsMapper();
    ObjectNode node = mapper.readValue(input, ObjectNode.class);
    ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();

    // Alternatively write to file ???
    System.out.println(ow.writeValueAsString(node);

} catch (IOException e) {
    // Do something
}