Read raster from PostGIS with GeoTools

Question

I would like to read raster from PostGIS. I can do it from files on disk, but I'm having difficulties to find examples reading from PostGIS. What do I have to change to set up the reader from files to PostGIS? This is how I do it with files:

        file= new File(filepath);
        }
        MainDialog.lastInputDir = file;
        AbstractGridFormat format = GridFormatFinder.findFormat(file);
        Hints hints = new Hints();
        if (format instanceof GeoTiffFormat) {
            hints = new Hints(Hints.FORCE_LONGITUDE_FIRST_AXIS_ORDER, Boolean.TRUE);
        }
        try {
            reader = format.getReader(file, hints);
            Style rasterStyle = null;
            GridCoverage2D cov = null;
            try {
                cov = reader.read(null);
            } catch (IOException giveUp) {
                throw new RuntimeException(giveUp);
            }

Answer 1

You will need the unsupported gt-postgis-raster module - which is currently being resurrected from being broken by the demise of the JDBC Image Mosaic module.

From the readme you need an XML file like:

<!-- 
  postgis raster config format, * = required element 
-->
<pgraster>
  <name></name>                       <!-- * name of the resulting coverage -->

  <!-- 
  database connection info, either name,host,port,etc... is required or jndi
  -->
  <database>                  
    <host></host>                     <!-- db hostname, defaults to 'localhost' -->
    <port></port>                     <!-- db port, defaults to '5432' -->
    <name></name>                     <!-- database name -->
    <user></user>                     <!-- database user -->
    <passwd></passwd>.                <!-- database password -->
    <jndi></jndi>                     <!-- JNDI data source name -->
  </database>

  <!--
  raster table / column config
  -->
  <raster>
    <table></table>                   <!-- * raster table name -->
    <schema></schema>                 <!-- raster table schema, defaults to 'public' -->
    <column></schema>                 <!-- raster table column, defaults to 'rast' -->
  </raster>

  <!--
  time column config
  -->
  <time>                              <!-- time dimension configuration -->
    <column>dstamp</column>           <!-- name of data/time column -->
  </time>

  <!-- 
  https://postgis.net/docs/postgis_gdal_enabled_drivers.html 
  -->
  <enableDrivers></enabledDrivers>.   <!-- Example: ENABLE_ALL -->
</pgraster>

And it looks like you read that in with something like:

PGRasterConfig config = new PGRasterConfig(file);
PGRasterReader reader = new PGRasterReader(config, null, null);
GridCoverage2D rast = reader.read(null);