Java calls GDAL to write a vector file to build a compilation environment

JDK environment variable configuration

Right-click Computer -> Properties -> Advanced System Settings -> Environment Variables - > New System Variables:

Create two new system variables JAVA_HOME, CLASSPATH

Variable name: JAVA_HOME

Variable value: C:\Program Files (x86)\Java\jdk1.5.0_22

Variable name: CLASSPATH

Variable value (note that the preceding dot and semicolon cannot be less): .;%JAVA_HOME%/lib

Variable name: JAVA_HOME

Add in front of Path (if there is no Path system variable, create a new one) " %JAVA_HOME%/bin; "

%JAVA_HOME%/bin;%SystemRoot%\system32;。。。。。。

Get GDAL Java Edition compiled files

There are two main ways to obtain GDAL Java compiled files

The first one: Download the GDAL source code and compile it with Visual Studio.

The second: Download the GDAL java library that has been compiled by others.

The second method is adopted here, to download 32-bit GDAl to get release-1600-dev.zip , unzip it, and extract the 5 files in the directory release-1600\bin\gdal\java, namely:

gdal.jar

gdalconstjni.dll

gdaljni.dll

ogrjni.dll

osrjni.dll

1 jar package, 4 dlls.

Create a new java project, put the jar package under the lib library of the project, and put the 4 dlls under the project root directory.

Run the demo, when ogr.RegisterAll () is executed to register all the drivers, the following two possible errors will be reported

Nativelibraryloadfailed.

java.lang.UnsatisfiedLinkError:noogrjniinjava.library.path

Exceptioninthread"main"java.lang.UnsatisfiedLinkError:RegisterAll

atorg.gdal.ogr.ogrJNI.RegisterAll(NativeMethod)

atorg.gdal.ogr.ogr.RegisterAll ( ogr.java:115 )

atcom.gdal.vector.ShapeFileWrite.main(ShapeFileWrite.java:20)

Reason: The 4 dlls are not placed under the project root directory.

or:

Nativelibraryloadfailed.

java.lang.UnsatisfiedLinkError:D:\InspurWorkspace\GDALTest01\ogrjni.dll:Can'tfinddependentlibraries

Exceptioninthread"main"java.lang.UnsatisfiedLinkError:RegisterAll

atorg.gdal.ogr.ogrJNI.RegisterAll(NativeMethod)

atorg.gdal.ogr.ogr.RegisterAll ( ogr.java:115 )

atcom.gdal.vector.ShapeFileWrite.main(ShapeFileWrite.java:20)

The reason is that ogrjni.dll lacks other dlls that depend on it. Using a dll dependency tool to check, ogrjni.dll also depends on a called gdal111.dll.

问题到这一步，如果你想直接把这个gdal111.dll拷贝到工程跟目录下面去的话，会发现这个gdal111.dll又依赖于其它dll，所以自然而然，你想到了把这个目录下面的所有dll全部拷贝到工程根目录下面去，这样程序能够执行了，但是你会发现，你每建一个工程都需要这样做。

配置GDAL Dll调用路径

上述问题转换为java如何调用c++编译后的dll库。目前自己找到3种方法

方法1、直接将dll文件放在java工程根目录下面。

GDAL Java demo编译成功。优点：思路简单、32为、64位dll可以很方便的切换。缺点：每次新建工程都需要拷贝这些dll，增加工程文件大小，操作繁琐。

方法2、在Eclipse里面编译java的时候设定其Java Build Path-》Source 选择工程名下面的 Native library location选择dll所在路径。

GDAL Java demo编译失败，

方法3、设置系统环境变量指定dll路径，将其加入Path中

前两种方法是从别人那里看到的，第3种方法是自己想出来的，想法也很简单，在操作系统中运行一个程序（命令）时，如果没有指定绝对路径，它会先去程序本身所在的路径下面去寻找可执行文件，当找不到这些文件的时候，会去环境变量Path下面去寻找需要的东西。所以我们只需要将这个GDAL dll的路径加入到Path里面就行了，

右键计算机——》属性——》高级系统设置——》环境变量——》新建系统变量：

新建两个系统变量GDAL32_DLL

变量名： GDAL32_DLL

变量值：C:\GDAL\release-1600-win32-dev\release-1600\bin;C:\GDAL\release-1600-win32-dev\release-1600\bin\gdal\java

名字可以自己定义，指定GDAL DLL路径位置，和GDAL java版编译出路径。

在Path前面增加（如果没有Path系统变量，则新建）" %GDAL32_DLL%;"，即path变为

%GDAL32_DLL%;%JAVA_HOME%/。。。。。。

注意：将dll加入Path后，需要重启电脑，或者先注销后在进入windows系统，才会生效。

Java调用GDAL写入矢量文件 Demo

package com.gdal.vector;

import org.gdal.gdal.gdal;
import org.gdal.ogr.DataSource;
import org.gdal.ogr.Feature;
import org.gdal.ogr.FeatureDefn;
import org.gdal.ogr.FieldDefn;
import org.gdal.ogr.Geometry;
import org.gdal.ogr.Layer;
import org.gdal.ogr.ogr;

public class ShapeFileWrite {
	
	public static void main(String[] args) {
	
	
	         String strVectorFile ="D:\\test\\gdal\\testShap05.shp";  
	   
	         // 注册所有的驱动
	         ogr.RegisterAll();
	        
	         // 为了支持中文路径，请添加下面这句代码
	         gdal.SetConfigOption("GDAL_FILENAME_IS_UTF8","NO");
	         // 为了使属性表字段支持中文，请添加下面这句
	         gdal.SetConfigOption("SHAPE_ENCODING","");
	 
	         //创建数据，这里以创建ESRI的shp文件为例
	         String strDriverName = "ESRI Shapefile";
	         org.gdal.ogr.Driver oDriver =ogr.GetDriverByName(strDriverName);
	         if (oDriver == null)
	         {
	                   System.out.println(strVectorFile+ " 驱动不可用！\n");
	                   return;
	         }
	 
	         // 创建数据源
	         DataSource oDS = oDriver.CreateDataSource(strVectorFile,null);
	         if (oDS == null)
	         {
	                   System.out.println("创建矢量文件【"+ strVectorFile +"】失败！\n" );
	                   return;
	         }
	 
	         // 创建图层，创建一个多边形图层，这里没有指定空间参考，如果需要的话，需要在这里进行指定
	         Layer oLayer =oDS.CreateLayer("TestPolygon", null, ogr.wkbPolygon, null);
	         if (oLayer == null)
	         {
	                   System.out.println("图层创建失败！\n");
	                   return;
	         }
	 
	         // 下面创建属性表
	         // 先创建一个叫FieldID的整型属性
	         FieldDefn oFieldID = new FieldDefn("FieldID", ogr.OFTInteger);
	         oLayer.CreateField(oFieldID, 1);
	 
	         // 再创建一个叫FeatureName的字符型属性，字符长度为50
	         FieldDefn oFieldName = new FieldDefn("FieldName", ogr.OFTString);
	         oFieldName.SetWidth(100);
	         oLayer.CreateField(oFieldName, 1);
	 
	         FeatureDefn oDefn =oLayer.GetLayerDefn();
	 
	         // 创建三角形要素
	         Feature oFeatureTriangle = new Feature(oDefn);
	         oFeatureTriangle.SetField(0, 0);
	         oFeatureTriangle.SetField(1, "三角形");
	         Geometry geomTriangle =Geometry.CreateFromWkt("POLYGON ((0 0,20 0,10 15,0 0))");
	         oFeatureTriangle.SetGeometry(geomTriangle);
	 
	         oLayer.CreateFeature(oFeatureTriangle);
	 
	         // 创建矩形要素
	         Feature oFeatureRectangle = new Feature(oDefn);
	         oFeatureRectangle.SetField(0, 1);
	         oFeatureRectangle.SetField(1, "矩形");
	         Geometry geomRectangle =Geometry.CreateFromWkt("POLYGON ((30 0,60 0,60 30,30 30,30 0))");
	         oFeatureRectangle.SetGeometry(geomRectangle);
	 
	         oLayer.CreateFeature(oFeatureRectangle);
	 
	         // 创建五角形要素
	         Feature oFeaturePentagon = new Feature(oDefn);
	         oFeaturePentagon.SetField(0, 2);
	         oFeaturePentagon.SetField(1, "五角形");
	         Geometry geomPentagon =Geometry.CreateFromWkt("POLYGON ((70 0,85 0,90 15,80 30,65 15,70 0))");
	         oFeaturePentagon.SetGeometry(geomPentagon);
	 
	         oLayer.CreateFeature(oFeaturePentagon);
	         
	         //写入文件
	         oLayer.SyncToDisk();
	         oDS.SyncToDisk();
	 
	         System.out.println("\n数据集创建完成！\n");
	}  
}