GeoTools应用-DATA
Geotools是Java语言编写的开源GIS工具包。该项目已有十多年历史，生命力旺盛，代码非常丰富，包含多个开源GIS项目，并且基于标准的GIS接口。Geotools主要提供各种GIS算法，各种数据格式的读写和显示。在显示方面要差一些，只是用Swing实现了地图的简单查看和操作。但是用户可以根据Geotools提供的算法自己实现地图的可视化。OpenJump和udig就是基于Geotools的。
Geotools用到的两个较重要的开源GIS工具包是JTS和GeoAPI。前者主要是实现各种GIS拓扑算法，也是基于GeoAPI的。但是由于两个工具包的GeoAPI分别采用不同的Java代码实现，所以在使用时需要相互转化。Geotools又根据两者定义了部分自己的GeoAPI，所以代码显得臃肿，有时容易混淆。由于GeoAPI进展缓慢，Geotools自己对其进行了扩充。另外，Geotools现在还只是基于2D图形的，缺乏对3D空间数据算法和显示的支持。
一、Geotools The Open Source Java GIS Toolkit
http://geotools.org/ Geotools官方网站
http://docs.geotools.org/latest/javadocs/ Geotools API在线文档
http://docs.codehaus.org/display/GEOTDOC/Home Geotools用户指南
http://repo.opengeo.org Geotools的maven仓库地址
http://download.osgeo.org/webdav/geotools/ maven仓库地址
POM.xml配置
<repositories>
<repository>
<id>osgeo</id>
<name>Open Source Geospatial Foundation Repository</name>
<url>http://download.osgeo.org/webdav/geotools/</url>
</repository>
<repository>
<snapshots>
<enabled>true</enabled>
</snapshots>
<id>opengeo</id>
<name>OpenGeo Maven Repository</name>
<url>http://repo.opengeo.org</url>
</repository>
</repositories>
eg:取到gt-main.jar的依赖关系
<dependency> <groupId>org.geotools</groupId> <artifactId>gt-main</artifactId> <version>8.4</version> </dependency>
二、OpenGIS 软件架构
org.geotools.data
包负责地理数据的读写(如:ShavefileReader用于读取shpfile数据)，org.geotools.geometry
包负责提供对JTs的调用接口，以将地理数据封装成JTS中定义的几何对象(Geometry)，
org.geotools.feature包负责封装空间几何要素对象(Feature)，对应于地图中一个实体，
包含:空间数据(Geometry)、属性数据(Aitribute)、参考坐标系(Refereneedsystem)、
最小外包矩形(EnveloPe)等属性，是Gls操作的核心数据模型。
Geotools 读取shp 数据格式的例子:
/**
* 读取shap格式的文件
*
* @param path
*/
public void readSHP(String path) {
ShapefileDataStore shpDataStore = null;
try {
shpDataStore = new ShapefileDataStore(new File(path).toURI()
.toURL());
shpDataStore.setStringCharset(Charset.forName("GBK"));
// 文件名称
String typeName = shpDataStore.getTypeNames()[0];
FeatureSource<SimpleFeatureType, SimpleFeature> featureSource = null;
featureSource = (FeatureSource<SimpleFeatureType, SimpleFeature>) shpDataStore
.getFeatureSource(typeName);
FeatureCollection<SimpleFeatureType, SimpleFeature> result = featureSource
.getFeatures();
SimpleFeatureType schema = result.getSchema(); // schema
List<AttributeDescriptor> columns = schema
.getAttributeDescriptors();
FeatureIterator<SimpleFeature> itertor = result.features();
/*
* 或者使用 FeatureReader FeatureReader reader =
* DataUtilities.reader(result); while(reader.hasNext()){
* SimpleFeature feature = (SimpleFeature) reader.next(); }
*/
while (itertor.hasNext()) {
SimpleFeature feature = itertor.next();
for (AttributeDescriptor attributeDes : columns) {
String attributeName = attributeDes.getName().toString();// attribute
if (attributeName.equals("the_geom"))
continue;
feature.getAttribute(attributeName); // attributeValue
}
Geometry g = (Geometry) feature.getDefaultGeometry();// Geometry
}
itertor.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 读取dbf格式的文件，只存储属性值，不存储空间值
*
* @param path
*/
public void readDBF(String path) {
DbaseFileReader reader = null;
try {
reader = new DbaseFileReader(new ShpFiles(path), false,
Charset.forName("GBK"));
DbaseFileHeader header = reader.getHeader();
int numFields = header.getNumFields();
for (int i = 0; i < numFields; i++) {
header.getFieldName(i);
header.getFieldType(i);// 'C','N'
header.getFieldLength(i);
}
// 迭代读取记录
while (reader.hasNext()) {
try {
Object[] entry = reader.readEntry();
for (int i = 0; i < numFields; i++) {
String title = header.getFieldName(i);
Object value = entry[i];
String name = title.toString(); // column
String info = value.toString(); // value
}
} catch (Exception e) {
e.printStackTrace();
}
}
} catch (Exception ex) {
ex.printStackTrace();
} finally {
if (reader != null) {
// 关闭
try {
reader.close();
} catch (Exception e) {
}
}
}
}
输出一个shp文件
/**
* 创建shp文件
*
* @param outPath
*/
public void createShp(String outPath) {
try {
// 定义属性
final SimpleFeatureType TYPE = DataUtilities.createType("Location",
"location:Point," + "NAME:String," + "INFO:String,"
+ "OWNER:String");
FeatureCollection<SimpleFeatureType, SimpleFeature> collection = FeatureCollections.newCollection();
GeometryFactory geometryFactory = new GeometryFactory();
SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
double latitude = Double.parseDouble("116.123456789");
double longitude = Double.parseDouble("39.120001");
String NAME = "运通110路";
String INFO = "白班车,学生票有效";
String OWNER = "001";
//创建坐标
Point point = geometryFactory.createPoint(new Coordinate(longitude,latitude));
//创建属性值
Object[] obj = {point, NAME, INFO, OWNER };
//构造一个Feature
SimpleFeature feature = featureBuilder.buildFeature(null, obj);
//添加到集合
collection.add(feature);
// shap文件的输出路径
File newFile = new File(outPath);
Map<String, Serializable> params = new HashMap<String, Serializable>();
params.put("url", (Serializable) newFile.toURI().toURL());
params.put("create spatial index", (Serializable) Boolean.TRUE);
ShapefileDataStoreFactory dataStoreFactory = new ShapefileDataStoreFactory();
ShapefileDataStore newDataStore = (ShapefileDataStore) dataStoreFactory
.createNewDataStore(params);
newDataStore.createSchema(TYPE);
newDataStore.setStringCharset(Charset.forName("GBK"));
newDataStore.forceSchemaCRS(DefaultGeographicCRS.WGS84);
String typeName = newDataStore.getTypeNames()[0];
ShapefileFeatureLocking featureSource = (ShapefileFeatureLocking) newDataStore
.getFeatureSource(typeName);
// 创建一个事务
Transaction transaction = new DefaultTransaction("create");
featureSource.setTransaction(transaction);
try {
featureSource.addFeatures(collection);
// 提交事务
transaction.commit();
} catch (Exception problem) {
problem.printStackTrace();
transaction.rollback();
} finally {
transaction.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
org.geotools.data.DataUtilities
a facade classes which can help simplify common data wrangling chores 简化繁琐的通用数据
(1)、定义属性
FeatureType TYPE = DataUtilities.createType("Location",
"location:Point," + "NAME:String," + "INFO:String,"+ "OWNER:String");
(2) DataUtilities.schema
You can use this method to quickly get a representation of a FeatureType 返回FeatureType的schema
//返回schema
DataUtilities.spec(featureType))
(3) DataUtilities.collection Feature数组转换为Feature集合
DataUtilities has helper methods to turn almost anything into a FeatureCollection
Feature[] array;
....
return DataUtilties.collection( array );
(4) DataUtilities.reader 格式化
convert a perfectly good collection to FeatureReader format.
FeatureCollection collection;
FeatureReader reader = DataUtilities.reader( collection );
附:shp 格式文件介绍
Shapefile file extensions
.shp—The main file that stores the feature geometry. Required.
.shx—The index file that stores the index of the feature geometry. Required.
.dbf—The dBASE table that stores the attribute information of features. Required.There is a one-to-one relationship between geometry and attributes, which is based on record number.
.prj—The file that stores the coordinate system information. Used by ArcGIS.
DBF文件中的数据类型FieldType
代码 数据类型 允许输入的数据
B 二进制型 各种字符。
C 字符型 各种字符。
D 日期型 用于区分年、月、日的数字和一个字符，内部存储按照YYYYMMDD格式。
G (Generalor OLE) 各种字符。
N 数值型(Numeric) - . 0 1 2 3 4 5 6 7 8 9
L 逻辑型（Logical）? Y y N n T t F f (? 表示没有初始化)。
M (Memo) 各种字符。