【geotools随笔】FeatureType的创建与修改

在创建一个新的Feature对象前要定义一个FeatureType

SimpleFeatureTypeBuilder b = new SimpleFeatureTypeBuilder();

//设置名字
b.setName( "Flag" );

//添加属性
b.add( "name", String.class );
b.add( "classification", Integer.class );
b.add( "height", Double.class );

//add a geometry property
b.setCRS( DefaultGeographicCRS.WSG84 ); // set crs first
b.add( "location", Point.class ); // then add geometry

//build the type
final SimpleFeatureType TYPE = b.buildFeatureType();

或者

final SimpleFeatureType TYPE =
                DataUtilities.createType(
                        "Location",
                        "the_geom:Point:srid=4326,"
                        + // <- the geometry attribute: Point type
                        "name:String,"
                        + // <- a String attribute
                        "number:Integer" // a number attribute
                        );
        System.out.println("TYPE:" + TYPE);

抱歉，您没法改，因为其是用final修饰的
但是，您可以创建一个新的FeatureType

SimpleFeatureType lineType = DataUtilities.createType("LINE", "geom:LineString,name:"",id:0");
SimpleFeatureTypeBuilder b = new SimpleFeatureTypeBuilder();
//使用预先存在的要素类型的状态初始化生成器
b.init( lineType );
b.setName("POINT");
b.add(0, "geom", Point.class );
SimpleFeatureType pointType = b.buildFeatureType();

FeatureCollection无法通过foreach来读取，FeatureCollection是对实时数据流的包装；因此，我们需要确保在使用完后关闭迭代器。

try (SimpleFeatureIterator iterator = features.features()) {
            while (iterator.hasNext()) {
                SimpleFeature feature = iterator.next();
                // process feature
            }
        }

这里try的写法和一般有些不同，它使用了try-with-resource结构，会在try完毕后自动关闭stream。

DataUtilities是一个数据工具类，类似java里的util，全是静态方法。

对于制作测试用例时快速创建 FeatureType 非常有用，有以下两个方法

public static SimpleFeatureType createType(String typeName, String typeSpec)
public static SimpleFeatureType createType(String namespace, String name, String typeSpec)

快速创建一个FeatureType

SimpleFeatureType lineType = DataUtilities.createType("LINE", "centerline:LineString,name:"",id:0");

也可以选择使用类名

SimpleFeatureType schema = DataUtilities.createType("EDGE", "edge:Polygon,name:String,timestamp:java.util.Date");

顺便把参考系也加上

SimpleFeatureType lineType = DataUtilities.createType("LINE", "centerline:LineString:srid=32615,name:"",id:0");

使用命名空间

SimpleFeatureType lineType = DataUtilities.createType("http://somewhere.net/","LINE", "centerline:LineString,name:"",id:0");

无法修改，但可以创建一个副本

FeatureType schema = DataUtilities.createType("EDGE", "edge:Polygon,name:String");
System.out.println("1:"+schema.hashCode());
CoordinateReferenceSystem crs = CRS.decode( "EPSG:4326" );
schema = DataUtilities.createSubType((SimpleFeatureType) schema, null, crs );
System.out.println("2:"+schema.hashCode());

        FeatureType schema = DataUtilities.createType("EDGE", "edge:Polygon,name:String,timestamp:java.util.Date");
        System.out.println(schema);
        CoordinateReferenceSystem crs = CRS.decode( "EPSG:4326" );
        schema = DataUtilities.createSubType((SimpleFeatureType) schema, new String[]{"edge","name"}, crs );
        System.out.println(schema);