339 lines
12 KiB
Markdown
339 lines
12 KiB
Markdown
---
|
||
title: GeoTools-创建要素Feature
|
||
date: 2023-11-19
|
||
author: ac
|
||
categries:
|
||
- GIS
|
||
tags:
|
||
- GeoTools
|
||
---
|
||
|
||
### GeoTools-创建要素
|
||
|
||
> csv2shp，通过csv转点shp文件，学习：
|
||
>
|
||
> 1. 如何创建`FeatureType`、`FeatureCollection`和`Features`；
|
||
> 2. 通过`GeometryFactory`构建`Points`点集；
|
||
> 3. 输出shp文件；
|
||
> 4. 设置投影。
|
||
|
||
#### 1.数据准备
|
||
|
||
下载一份[csv文件](https://docs.geotools.org/latest/userguide/_downloads/d4bcf8751cc3f33a9fb673902a960e53/locations.csv) ，内容格式如下：
|
||
|
||
```text
|
||
LAT, LON, CITY, NUMBER
|
||
46.066667, 11.116667, Trento, 140
|
||
44.9441, -93.0852, St Paul, 125
|
||
13.752222, 100.493889, Bangkok, 150
|
||
45.420833, -75.69, Ottawa, 200
|
||
44.9801, -93.251867, Minneapolis, 350
|
||
46.519833, 6.6335, Lausanne, 560
|
||
48.428611, -123.365556, Victoria, 721
|
||
-33.925278, 18.423889, Cape Town, 550
|
||
-33.859972, 151.211111, Sydney, 436
|
||
41.383333, 2.183333, Barcelona, 914
|
||
39.739167, -104.984722, Denver, 869
|
||
52.95, -1.133333, Nottingham, 800
|
||
45.52, -122.681944, Portland, 840
|
||
37.5667,129.681944,Seoul,473
|
||
50.733992,7.099814,Bonn,700,2016
|
||
```
|
||
|
||
#### 2.添加依赖
|
||
|
||
```xml
|
||
<dependencies>
|
||
<dependency>
|
||
<groupId>org.geotools</groupId>
|
||
<artifactId>gt-shapefile</artifactId>
|
||
<version>${geotools.version}</version>
|
||
</dependency>
|
||
<dependency>
|
||
<groupId>org.geotools</groupId>
|
||
<artifactId>gt-epsg-hsql</artifactId>
|
||
<version>${geotools.version}</version>
|
||
</dependency>
|
||
</dependencies>
|
||
<repositories>
|
||
<repository>
|
||
<id>osgeo</id>
|
||
<name>OSGeo Release Repository</name>
|
||
<url>https://repo.osgeo.org/repository/release/</url>
|
||
<snapshots><enabled>false</enabled></snapshots>
|
||
<releases><enabled>true</enabled></releases>
|
||
</repository>
|
||
<repository>
|
||
<id>osgeo-snapshot</id>
|
||
<name>OSGeo Snapshot Repository</name>
|
||
<url>https://repo.osgeo.org/repository/snapshot/</url>
|
||
<snapshots><enabled>true</enabled></snapshots>
|
||
<releases><enabled>false</enabled></releases>
|
||
</repository>
|
||
</repositories>
|
||
```
|
||
|
||
#### 3. 示例
|
||
|
||
```java
|
||
package learning;
|
||
|
||
import org.geotools.api.feature.simple.SimpleFeature;
|
||
import org.geotools.api.feature.simple.SimpleFeatureType;
|
||
import org.geotools.data.DataUtilities;
|
||
import org.geotools.data.shapefile.ShapefileDataStore;
|
||
import org.geotools.data.shapefile.ShapefileDataStoreFactory;
|
||
import org.geotools.feature.simple.SimpleFeatureBuilder;
|
||
import org.geotools.geometry.jts.JTSFactoryFinder;
|
||
import org.geotools.swing.data.JFileDataStoreChooser;
|
||
import org.locationtech.jts.geom.Coordinate;
|
||
import org.locationtech.jts.geom.GeometryFactory;
|
||
import org.locationtech.jts.geom.Point;
|
||
|
||
import javax.swing.*;
|
||
import java.io.BufferedReader;
|
||
import java.io.File;
|
||
import java.io.FileReader;
|
||
import java.io.Serializable;
|
||
import java.util.ArrayList;
|
||
import java.util.HashMap;
|
||
import java.util.List;
|
||
import java.util.Map;
|
||
|
||
/**
|
||
* @author ac
|
||
* @date 2023/11/20 15:44
|
||
*/
|
||
public class Csv2Shape {
|
||
public static void main(String[] args) throws Exception {
|
||
// Set cross-platform look & feel for compatability
|
||
UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
|
||
|
||
File file = JFileDataStoreChooser.showOpenFile("csv", null);
|
||
if (file == null) {
|
||
return;
|
||
}
|
||
|
||
/*
|
||
* 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.
|
||
*
|
||
* 通过 DataUtilities 创建 FeatureType ，类似定义shp文件的名称、几何类型、属性字段、空间参考等信息。
|
||
* createType (String typeName, String typeSpec)
|
||
* typeName:要素名称
|
||
* typeSpec：是"name:Type,name2:Type2,..."格式的字符串，用于定义要素的属性字段，其中Type的类型有：
|
||
* Interger（int、Interger）
|
||
* Double（Double, double）
|
||
* String（"",String,string）
|
||
* Geometry（Point,LineString,Polygon,MultiLineString,MultiPolygon,MultiPoint,GeometryCollection）
|
||
* 还可以是 UUID、Date或是Java的类的全名（含包名）
|
||
* 示例：
|
||
* name:"",age:0,geom:Geometry,centroid:Point,url:java.io.URL"
|
||
* id:String,polygonProperty:Polygon:srid=32615
|
||
*/
|
||
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);
|
||
|
||
/*
|
||
* A list to collect features as we create them.
|
||
*/
|
||
List<SimpleFeature> features = new ArrayList<>();
|
||
|
||
/*
|
||
* GeometryFactory will be used to create the geometry attribute of each feature,
|
||
* using a Point object for the location.
|
||
* 创建几何工厂实例，要素构建者实例
|
||
* 通过缓冲流一行行读取，解析数据，构建Point实例
|
||
*/
|
||
GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory();
|
||
SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
|
||
|
||
try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
|
||
/* First line of the data file is the header */
|
||
String line = reader.readLine();
|
||
System.out.println("Header: " + line);
|
||
|
||
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[0]);
|
||
double longitude = Double.parseDouble(tokens[1]);
|
||
String name = tokens[2].trim();
|
||
int number = Integer.parseInt(tokens[3].trim());
|
||
|
||
/* Longitude (= x coord) first ! */
|
||
// 创建几何实例geometry - point
|
||
Point point = geometryFactory.createPoint(new Coordinate(longitude, latitude));
|
||
|
||
// 创建要素实例feature
|
||
// feature
|
||
// ↙ ↘
|
||
// geometry properties
|
||
|
||
featureBuilder.add(point);
|
||
featureBuilder.add(name);
|
||
featureBuilder.add(number);
|
||
//buildFeature(id)创建一个要素,ID可以是null,当ID为null时会由builder内部生成
|
||
SimpleFeature feature = featureBuilder.buildFeature(null);
|
||
features.add(feature);
|
||
}
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Get an output file name and create the new shapefile
|
||
*
|
||
* 设置输出路径
|
||
*/
|
||
File newFile = getNewShapeFile(file);
|
||
|
||
// 创建shapefile类型的数据存储工厂实例
|
||
ShapefileDataStoreFactory dataStoreFactory = new ShapefileDataStoreFactory();
|
||
|
||
Map<String, Serializable> params = new HashMap<>();
|
||
params.put("url", newFile.toURI().toURL());
|
||
params.put("create spatial index", Boolean.TRUE);
|
||
|
||
// 创建一个空的数据存储
|
||
ShapefileDataStore newDataStore = (ShapefileDataStore) dataStoreFactory.createNewDataStore(params);
|
||
|
||
/*
|
||
* TYPE is used as a template to describe the file contents
|
||
* 添加类型描述
|
||
*/
|
||
newDataStore.createSchema(TYPE);
|
||
|
||
/*
|
||
* Write the features to the shapefile
|
||
* 创建“create”类型的事务，输出shapefile文件
|
||
*/
|
||
Transaction transaction = new DefaultTransaction("create");
|
||
|
||
String typeName = newDataStore.getTypeNames()[0];
|
||
SimpleFeatureSource featureSource = newDataStore.getFeatureSource(typeName);
|
||
SimpleFeatureType SHAPE_TYPE = featureSource.getSchema();
|
||
/*
|
||
* The Shapefile format has a couple limitations:
|
||
* - "the_geom" is always first, and used for the geometry attribute name
|
||
* - "the_geom" must be of type Point, MultiPoint, MuiltiLineString, MultiPolygon
|
||
* - Attribute names are limited in length
|
||
* - Not all data types are supported (example Timestamp represented as Date)
|
||
*
|
||
* Each data store has different limitations so check the resulting SimpleFeatureType.
|
||
*/
|
||
System.out.println("SHAPE:" + SHAPE_TYPE);
|
||
|
||
if (featureSource instanceof SimpleFeatureStore) {
|
||
SimpleFeatureStore featureStore = (SimpleFeatureStore) featureSource;
|
||
/*
|
||
* SimpleFeatureStore has a method to add features from a
|
||
* SimpleFeatureCollection object, so we use the ListFeatureCollection
|
||
* class to wrap our list of features.
|
||
*/
|
||
SimpleFeatureCollection collection = new ListFeatureCollection(TYPE, features);
|
||
featureStore.setTransaction(transaction);
|
||
try {
|
||
featureStore.addFeatures(collection);
|
||
transaction.commit();
|
||
} catch (Exception problem) {
|
||
problem.printStackTrace();
|
||
transaction.rollback();
|
||
} finally {
|
||
transaction.close();
|
||
}
|
||
System.exit(0); // success!
|
||
} else {
|
||
System.out.println(typeName + " does not support read/write access");
|
||
System.exit(1);
|
||
}
|
||
}
|
||
/**
|
||
* Prompt the user for the name and path to use for the output shapefile
|
||
* 弹窗让用户选择新生成的shp文件的保存位置
|
||
*
|
||
* @param csvFile the input csv file used to create a default shapefile name
|
||
* @return name and path for the shapefile as a new File object
|
||
*/
|
||
private static File getNewShapeFile(File csvFile) {
|
||
String path = csvFile.getAbsolutePath();
|
||
String newPath = path.substring(0, path.length() - 4) + ".shp";
|
||
|
||
JFileDataStoreChooser chooser = new JFileDataStoreChooser("shp");
|
||
chooser.setDialogTitle("Save shapefile");
|
||
chooser.setSelectedFile(new File(newPath));
|
||
|
||
int returnVal = chooser.showSaveDialog(null);
|
||
|
||
if (returnVal != JFileDataStoreChooser.APPROVE_OPTION) {
|
||
// the user cancelled the dialog
|
||
System.exit(0);
|
||
}
|
||
|
||
File newFile = chooser.getSelectedFile();
|
||
if (newFile.equals(csvFile)) {
|
||
System.out.println("Error: cannot replace " + csvFile);
|
||
System.exit(0);
|
||
}
|
||
|
||
return newFile;
|
||
}
|
||
}
|
||
```
|
||
|
||
#### 4. 归纳
|
||
|
||
下面是Java中的一些对象与`Geospatial`中的类的对应关系：
|
||
|
||
| Java | Geospatial |
|
||
|:-------- |:------------- |
|
||
| `Object` | `Feature` |
|
||
| `Class` | `FeatureType` |
|
||
| `Field` | `Attribute` |
|
||
| `Method` | `Operation` |
|
||
|
||
1. 先创建 `SimpleFeatureType`，就像新建了一个`shpefile`文件一样，定义了shp 文件名和属性字段。
|
||
2. 通过缓冲流解析文件中的坐标和属性信息，使用`GeometryFactory`几何工厂实例创建几何实例，再通过`featureBuilder`构建要素实例`feature`
|
||
|
||
##### 数据存储
|
||
|
||
|
||
|
||
`DataStore`代表一份要素数据的物理的源，如`shpaefile`文件、数据库（要素会转为SimpleFeature实例对象）。
|
||
|
||
##### 要素存储
|
||
|
||
`FeatureSource` 提供更易于操作feature data要素数据的API，当使用数据源(如shapefile或数据库表)时，您将首先创建一个`DataStore`对象来连接到物理源，然后检索一个`FeatureSource`来处理要素数据。
|
||
|
||
|
||
|
||
> `FeatureSource`是用来【读取】要素的类似`View`，而其子类`FeatureStore`是用来【读写】要素的类似于`Table`
|
||
|
||
```java
|
||
File file = ...
|
||
FileDataStore store = FileDataStoreFinder.getDataStore(file);
|
||
FeatureSource featureSource = store.getFeatureSource();
|
||
```
|
||
|
||
##### **事务**
|
||
|
||
`Transaction` 是有要素存储`FeatureStore`的事务控制器。
|
||
|
||
在这个接口的帮助下，可以安全地修改Shapefiles、数据库等。事务还可以在使用锁定`Feature`要素时提供授权。
|
||
|
||
所有操作都被认为是在一个事务中进行的。`Transaction.AUTO_COMMIT`用于表示自动提交事务模式。
|
||
|
||
#### 参考文章
|
||
|
||
[1] Feature Tutorial https://docs.geotools.org/latest/userguide/tutorial/feature/csv2shp.html
|