geoserver源码学习与扩展——CSV转shapefile文件

基于geotools实现csv转换为shapefile文件。

1、读取CSV文件，将其装入FeatureCollection；

2、利用ShapefileDumper类将FeatureCollection转存到硬盘；

 　　　/*
　　　　* transform CSV to FeatureCollection
　　　　*/
 1     public void processCSVFile(File csvFile){

        ListFeatureCollection collection;
        try{
            typeName = csvFile.getName().replace(".", "_");
            typeName = replaceBlank(typeName);
            BufferedReader reader = new BufferedReader(new FileReader(csvFile));
            try{
                /* First line of the data file is the header */
                String line = reader.readLine();
                System.out.println("Header: " + line);

                /*
                 * We use the DataUtilities class to create a FeatureType that will describe the data in our
                 * shapefile.
                 * 
                 * See also the createFeatureType method below for another, more flexible approach.
                 */
                String[] strArray  = line.split("\,");
                int latDex = -1;
                int longDex = -1;
                List<String> typeSpec = new ArrayList<String>();
                typeSpec.add("the_geom:Point:srid="+ SRID); // <- the geometry attribute: Point type
                for(int i = 0; i < strArray.length; i ++){
                    if(strArray[i].contains("Lat")){
                        latDex = i;
                    }
                    else if(strArray[i].contains("Long")){
                        longDex = i;
                    }
                    else{
                        typeSpec.add(strArray[i] + ":String");    //all String type
                    }
                }
                if(CreateCluster)
                    typeSpec.add("cluster:String");    //add cluster field
                String typeSpecs = String.join(",", typeSpec);
                final SimpleFeatureType TYPE = DataUtilities.createType(typeName,
                                typeSpecs // other attribute
                        );
                /*
                 * GeometryFactory will be used to create the geometry attribute of each feature (a Point
                 * object for the location)
                 */
                GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory(null);
                SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
                /*
                 * We create a FeatureCollection into which we will put each Feature created from a record
                 * in the input csv data file
                 */
                collection = new ListFeatureCollection(TYPE);

                for (line = reader.readLine(); line != null; line = reader.readLine()) {
                    if (line.trim().length() > 0) { // skip blank lines
                        String tokens[] = line.split("\,");
                        double latitude = Double.parseDouble(tokens[latDex]);
                        double longitude = Double.parseDouble(tokens[longDex]);

                        /* Longitude (= x coord) first ! */
                        Point point = geometryFactory.createPoint(new Coordinate(longitude, latitude));

                        featureBuilder.add(point);;
                        for(int i = 0; i < tokens.length; i ++){
                            if(latDex != i && longDex != i){
                                String strVal = tokens[i].trim();
                                featureBuilder.add(strVal);
                            }
                        }

                        if(CreateCluster)
                            featureBuilder.add("");    //add cluster field value
                        SimpleFeature feature = featureBuilder.buildFeature(null);
                        collection.add(feature);
                    }
                }
            } finally {
                reader.close();
            }
            writeShapeFile(collection);

        }
        catch(Exception ex){
            System.out.println(ex.getMessage());
        }
    }

CSV文件并不包含各字段的类型说明，将经纬度字段转换为Geometry，其他字段都为String类型；

另外，DataUtilities.createType方法创建要素方案时，将所有的String类型的字段长度都设为了java环境下的默认长度254，若字段太多或要素太多会导致shapefile中的dbf文件过大，可参考DataUtilities类，编写自定义类将String类型长度设为自定义长度；

    /*
     * FeatureCollection to shapefile
    */
    private void writeShapeFile(SimpleFeatureCollection collection){
        final File baseDir = resourceLoader.getBaseDirectory();
        File shpDir = new File(baseDir.getAbsolutePath() + "/Data/upload");
        if(!shpDir.exists()){
            shpDir.mkdirs();
        }
        if(!shpDir.exists())
            return;

        ShapefileDumper dumper = new ShapefileDumper(shpDir);
        dumper.setMaxDbfSize(maxDbfSize);
        dumper.setMaxShpSize(maxShpSize);
        dumper.setCharset(Charset.forName(charSet));


        // target charset

        try {
            // if an empty result out of feature type with unknown geometry is created, the
            // zip file will be empty and the zip output stream will break
            boolean shapefileCreated = false;
            shapefileCreated |= dumper.dump(collection);

            // take care of the case the output is completely empty
            if(!shapefileCreated) {
                createEmptyWarning(shpDir);
            }

        }
        catch(Exception ex){
            System.out.println(ex.getMessage());
        }

    }

    private void createEmptyWarning(File tempDir) throws IOException {
        PrintWriter pw = null;
        try {
            pw = new PrintWriter(new File(tempDir, "README.TXT"));
            pw.print("The CSV Upload result is empty, and the geometric type of the features is unknwon:"
                    + "an empty point shapefile has been created");
        } finally {
            pw.close();
        }
    }