geotools学习（十）进程

进程

GeoTools流程系统是打包有用功能以便在应用程序中使用(或通过“web处理服务”(如GeoServer或52N)发布)的好方法。

当与流程引擎一起使用时，这些单独的流程可以链接在一起，形成有趣和有用的脚本。
这个过程数据结构比我们添加到GeoTools过滤器系统的功能更强大，能够根据需要处理大量数据。其基本思想与此类似，您可以编写一些简单的java代码并将其打包以供GeoTools库使用。
我们有很多选择:

• Annotations
• DataStructure

参考：

• Process

过程详解

这是创建流程的最快方法;这很好(只要您的过程产生一个结果)。

1. 添加一个依赖gt-process到您的项目:

<dependency>
  <groupId>org.geotools</groupId>
  <artifactId>gt-process</artifactId>
  <version>${geotools.version}</version>
</dependency>

2. 首先，我们需要创建一个扩展StaticMethodsProcessFactory的类:

/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2019, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 *
 */

package org.geotools.tutorial.process;

import org.geotools.process.factory.DescribeParameter;
import org.geotools.process.factory.DescribeProcess;
import org.geotools.process.factory.DescribeResult;
import org.geotools.process.factory.StaticMethodsProcessFactory;
import org.geotools.text.Text;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.OctagonalEnvelope;

public class ProcessTutorial extends StaticMethodsProcessFactory<ProcessTutorial> {

3. 我们需要做一点工作来填充构造函数

public ProcessTutorial() {
        super(Text.text("Tutorial"), "tutorial", ProcessTutorial.class);
    }

4. 我们现在可以实现我们的功能:

static public Geometry octagonalEnvelope( Geometry geom) {
    return new OctagonalEnvelope(geom).toGeometry(geom.getFactory());
}

5. 然后我们可以填写注释来描述我们的过程、结果和参数。

• @DescribeProcess
• @DescribeParameter
• @DescribeResult

  @DescribeProcess(
        title = "Octagonal Envelope",
        description = "Get the octagonal envelope of this Geometry."
    )
    @DescribeResult(description = "octagonal of geom")
    public static Geometry octagonalEnvelope(@DescribeParameter(name = "geom") Geometry geom) {
        return new OctagonalEnvelope(geom).toGeometry(geom.getFactory());
    }

6. 然后将其连接到工厂SPI(正如在函数教程中所做的那样)。
   创建文件:

• META-INF/services/org.geotools.process.ProcessFactory

7. 填写以下内容(每行一个实现类):

org.geotools.tutorial.process.ProcessTutorial

8. 就是这样，八角形信封现在出版了。

扩展尝试

• 尝试使用Processors实用程序类调用您的进程

        WKTReader wktReader = new WKTReader(new GeometryFactory());
        Geometry geom = wktReader.read("MULTIPOINT (1 1, 5 4, 7 9, 5 5, 2 2)");

        Name name = new NameImpl("tutorial", "octagonalEnvelope");
        Process process = Processors.createProcess(name);

        ProcessExecutor engine = Processors.newProcessExecutor(2);

        // quick map of inputs
        Map<String, Object> input = new KVP("geom", geom);
        Progress working = engine.submit(process, input);

        // you could do other stuff whle working is doing its thing
        if (working.isCancelled()) {
            return;
        }

        Map<String, Object> result = working.get(); // get is BLOCKING
        Geometry octo = (Geometry) result.get("result");

        System.out.println(octo);

它是这样的:

image.png

• 处理程序类还可以列出Map<String，参数>，允许您显示数据输入向导(就像连接到数据存储时一样)。

        Name name = new NameImpl("tutorial", "octagonalEnvelope");

        Map<String, Parameter<?>> paramInfo = Processors.getParameterInfo(name);