在Java中运行时从zip文件读取ESRI shapefile - DataStoreFinder.getDataStore(connectParameters)返回null

Question

我们正在构建一个上传包含ESRI-shapefile的zip文件的服务.该服务应该能够读取shapefile并对其内容进行处理.所以我构建了一个将zip文件解压缩到临时文件夹(System.getProperty("java.io.tmpdir")的子文件夹)的类.

另一个类从Unzip-class调用unzip方法,然后尝试使用Geotools读取解压缩的shapefile.它使用Geotools DataStoreFinder.getDataStore(Map params)方法从解压缩的shapefile创建数据存储区.这里出现问题:getDataStore-method返回null.我测试了URL,它看起来很好.URL所源自的文件是一个文件,可以由应用程序读取(使用shapefile.exists(),shapefile.isFile(),shapefile.canRead()进行测试).那么,可能出现什么问题呢？为什么我返回null？

这是(相关)代码:

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import org.geotools.data.DataStore;
import org.geotools.data.DataStoreFinder;
import org.geotools.data.FeatureSource;
import org.geotools.feature.FeatureCollection;
import org.geotools.feature.FeatureIterator;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;

import com.geodan.equus.entity.dataset.BasicFeature;
import com.geodan.equus.exception.EquusException;
import com.geodan.equus.processor.EquusProcessor;
import com.geodan.util.io.UnzipUtils;
import com.vividsolutions.jts.geom.Geometry;

public class ShapefileProcessor implements EquusProcessor
{

    private static final File TEMP_UNZIP_DIR = new File(
        System.getProperty("java.io.tmpdir") + File.separator
                + "atlas_temp_unzip_dir");

    public static Set<BasicFeature> importFeatures(final File zipFile)
        throws EquusException
    {
        // Check if the input file has the zipfile extension 
        if (!zipFile.getName().endsWith(".zip"))
        {
            throw new EquusException(
                    "The file is not a zipfile. It cannot be processed.");
        }

        // Unzip the file
        try
        {
            UnzipUtils.unzip(zipFile, TEMP_UNZIP_DIR);
        }
        catch (IOException error)
        {
            throw new EquusException("The zipfile cannot be unzipped.", error);
        }

        // Validate whether the unzipped folder contains a shapefile and return it
        File shapefile = new File("");
        try
        {
            shapefile = findShapefile(TEMP_UNZIP_DIR);
        }
        catch (IOException error)
        {
            throw new EquusException(
                    "The zipfile does not contain a shapefile. Cannot process its contents.",
                error);
        }

        // Collect the features from the shapefile and put them into an iterator 
        FeatureIterator<SimpleFeature> featureIterator;
        try
        {
            featureIterator = readShapefile(shapefile);
        }
        catch (EquusException e)
        {
            throw new EquusException(e.getMessage(), e);
        }

        // Create a Set filled with the features in the FeatureIterator
        Set<BasicFeature> features = createFeatureSet(featureIterator);

        return features;

    }

    private static File findShapefile(File unzipPath) throws IOException
    {
        File shapefile = new File("");
        // Find first .shp file in the unzip folder
        File[] unzippedFiles = unzipPath.listFiles();
        for (int i = 0; i < unzippedFiles.length; i++)
        {
            if (unzippedFiles[i].getName().endsWith(".shp"))
            {
                shapefile = new File(unzipPath + File.separator
                        + unzippedFiles[i].getName());
                break;
            }
        }
        if (shapefile.toString() == "")
        {
            throw new IOException("No shapefile present in '" + unzipPath
                + "'.");
        }
        return shapefile;
    }

    private static FeatureIterator<SimpleFeature> readShapefile(File shapefile)
        throws EquusException
    {
        // Collects the features from a shapefile and puts them into an iterator
        FeatureCollection<SimpleFeatureType, SimpleFeature> featureCollection;
        try
        {
            Map<String, URL> connectParameters = new HashMap<String, URL>();
            connectParameters.put("url", shapefile.toURI().toURL());
            DataStore dataStore = DataStoreFinder.getDataStore(connectParameters);
            String typeName = dataStore.getTypeNames()[0];
            FeatureSource<SimpleFeatureType, SimpleFeature> featureSource = dataStore.getFeatureSource(typeName);
                featureCollection = featureSource.getFeatures();
        }
        catch (Exception e)
        {
            throw new EquusException(
                    "Features cannot be retrieved from the shapefile.", e);
        }
        return featureCollection.features();
    }

    private static Set<BasicFeature> createFeatureSet(
            FeatureIterator<SimpleFeature> featureIterator)
    {
        SimpleFeature simpleFeature = null;
        Set<BasicFeature> features = new HashSet<BasicFeature>();
        while (featureIterator.hasNext())
        {
            simpleFeature = featureIterator.next();
            BasicFeature feature = new BasicFeature();
            feature.setGeometry((Geometry) simpleFeature.getDefaultGeometry());
            features.add(feature);
        }
        return features;
    }
}

Answer 1

尽管您的代码看起来是正确的，但我发现我们的代码库中关键行的实现略有不同：

Map<String, Object> map = new HashMap<>();
map.put(ShapefileDataStoreFactory.URLP.key, url);
map.put(ShapefileDataStoreFactory.CREATE_SPATIAL_INDEX.key, Boolean.TRUE);
DataStore shapefileStore = DataStoreFinder.getDataStore(map);