[postgis-users] How do I handle a ResultSet from a java request?

Andrew Davis drsockmonkee at gmail.com
Tue Oct 6 06:55:20 PDT 2015


Thanks...
I am just starting out on it.  I will be passing only about 40 point
features first.

I will make note of and go look at the stream... as well..

Andy
On Oct 6, 2015 8:53 AM, "Nicolas Ribot" <nicolas.ribot at gmail.com> wrote:

> Hi Andy,
>
> Your Java ResultSet contains one big row representing your geoJson
> document. You can pass it to the client by building a string from the
> resultset:
> String geojson = resultSet.getString(1);
>
> Be careful to the potential big size of the String: if you expect a big
> geojson document from the database, it may be wiser to stream it to the
> client from the JDBC connection instead of building a Java String.
>
> Nicolas
>
> On 6 October 2015 at 15:32, Andrew Davis <drsockmonkee at gmail.com> wrote:
>
>> Hi all..
>>
>> I'm sending my first question out so patience please.
>>
>> I've got a working servlet on my server that will query for and get
>> information back from my postgis DB.
>>
>> Up until now I have been just parsing the results and sending back a json
>> string.  I want to get a GeoJSON back from my db now.
>>
>> I've been working through the information I found here:
>>
>> http://www.postgresonline.com/journal/archives/267-Creating-GeoJSON-Feature-Collections-with-JSON-and-PostGIS-functions.html
>>
>> I can create the table with locations included and a geog value, and I
>> can run the query below
>>
>> SELECT row_to_json(fc)
>>  FROM ( SELECT 'FeatureCollection' As type, array_to_json(array_agg(f)) As features
>>  FROM (SELECT 'Feature' As type
>>     , ST_AsGeoJSON(lg.geog)::json As geometry
>>     , row_to_json((loc_id, loc_name)) As properties
>>    FROM locations As lg   ) As f )  As fc;
>>
>>
>> which brings back a single line string and is in the correct format all in PGAdmin3.
>>
>>
>> I have been trying to duplicate this from my server with java and am stuck at the point where I have
>>
>> run the query and have a 'thing' (ResultSet) but am unsure as to how to handle it and then pass it
>>
>> back to the client.
>>
>>
>> Any help would be welcome.
>>
>>
>> Andy..
>>
>>
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>
>
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