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World Wind Java开发之六——解析shape文件(上)
最近一直忙于导师项目的事情了,几天没更新了,昨天和今天研究了下WWJ解析shp文件的源代码,现在记录下,希望可以帮到更多的人!
上一篇博客:World Wind Java开发之五——读取本地shp文件只讲了如何加载shp文件,没有涉及到shp文件的解析,我们这篇博客紧接上一篇博客,利用WWJ来解析shp文件。首先来看用到的源码包和相关类,如下图所示。解析shp文件主要用到Shapefile(shapefile文件类)、ShapefileRecord(shape文件记录类)、DBaseRecord类以及DBaseField(字段类)
1、读取shapefile文件
由上图可以看出有要实例化一个shapefile对象有六种方法,以其中的两种为例,看下源码:
(1)
/** * Opens a Shapefile from an InputStream, and InputStreams to its optional * resources. * <p/> * The source Shapefile may be accompanied optional streams to an index * resource stream, an attribute resource stream, and a projection resource * stream. If any of these streams are null or cannot be read for any * reason, the Shapefile opens without that information. * <p/> * This throws an exception if the shapefile's coordinate system is * unsupported. * * @param shpStream * the shapefile geometry file stream. * @param shxStream * the index file stream, can be null. * @param dbfStream * the attribute file stream, can be null. * @param prjStream * the projection file stream, can be null. * @throws IllegalArgumentException * if the shapefile geometry stream <code>shpStream</code> is * null. * @throws WWRuntimeException * if the shapefile cannot be opened for any reason, or if the * shapefile's coordinate system is unsupported. */ public Shapefile(InputStream shpStream, InputStream shxStream, InputStream dbfStream, InputStream prjStream) { this(shpStream, shxStream, dbfStream, prjStream, null); }输入文件流分别对应着.shp .shx .dbf .prj文件
(2)
/** * Opens an Shapefile from a general source. The source type may be one of * the following: * <ul> * <li>{@link java.io.InputStream}</li> * <li>{@link java.net.URL}</li> * <li>{@link File}</li> * <li>{@link String} containing a valid URL description or a file or * resource name available on the classpath.</li> * </ul> * <p/> * The source Shapefile may be accompanied by an optional index file, * attribute file, and projection file. To be recognized by this Shapefile, * accompanying files must be in the same logical folder as the Shapefile, * have the same filename as the Shapefile, and have suffixes ".shx", * ".dbf", and ".prj" respectively. If any of these files do not exist, or * cannot be read for any reason, the Shapefile opens without that * information. * <p/> * This throws an exception if the shapefile's coordinate system is * unsupported, or if the shapefile's coordinate system is unsupported. * * @param source * the source of the shapefile. * @throws IllegalArgumentException * if the source is null or an empty string. * @throws WWRuntimeException * if the shapefile cannot be opened for any reason. */ public Shapefile(Object source) { this(source, null); }这种方法秩序给出shp文件的路径即可,但是若只有shp文件,缺少shx等文件则无法解析shape文件。
根据以上两种方法来实例化一个shapefile对象,源码如下:
String shpFilePath = "D:\\Users\\wwj_data\\states.shp"; String shxFilePath = "D:\\Users\\wwj_data\\states.shx"; String dbfFilePath = "D:\\Users\\wwj_data\\states.dbf"; String prjFilePath = "D:\\Users\\wwj_data\\states.prj"; Shapefile shapefile = new Shapefile(shpFilePath); System.out.println(shapefile.getShapeType());或者:---------------------------------------------------------------------------------------
String shpFilePath = "D:\\Users\\wwj_data\\states.shp"; String shxFilePath = "D:\\Users\\wwj_data\\states.shx"; String dbfFilePath = "D:\\Users\\wwj_data\\states.dbf"; String prjFilePath = "D:\\Users\\wwj_data\\states.prj"; InputStream shpInputStream = new FileInputStream(shpFilePath); InputStream shxInputStream = new FileInputStream(shxFilePath); InputStream dbfInputStream = new FileInputStream(dbfFilePath); InputStream prjInputStream = new FileInputStream(prjFilePath); // 实例化一个shapefile类 Shapefile shapefile = new Shapefile(shpInputStream, shxInputStream, dbfInputStream, prjInputStream); System.out.println(shapefile.getShapeType()); // shape类型
这里需要说明的一点是,一开始的时候我是用的Shapefile(Object source)方法,但是报错:Source is NULL,不知是什么原因;用下面这种方法就可以,这个可以不必太纠结。
2、获取shapefile文件的属性表信息
在shapefile.java文件中可以找到 attributeFile字段,包含shapefile文件的属性信息,但是其权限是protected,只需在原java文件中添加一个方法返回改字段值即可。改完源码,重新导出jar文件覆盖引用即可。
protected DBaseFile attributeFile;
/** * * @方法名称: getAttributesTable ; * @方法描述: 获取属性表 ; * @参数 :@return * @返回类型: DBaseFile ; * @创建人:奔跑的鸡丝 ; * @创建时间:2014-12-1 下午12:55:33; * @throws */ public DBaseFile getAttributesTable() { return this.attributeFile; }获取属性表后,首先要获取属性表的基本信息,如:shape文件的类型、字段个数以及记录个数。另外输出所有字段名
// 获取shp属性表 DBaseFile dBaseFile = shapefile.getAttributesTable(); int fieldCount = dBaseFile.getNumberOfFields(); // 字段数 int recordsCount = dBaseFile.getNumberOfRecords(); // 记录数 System.out.println("字段数为:" + fieldCount); System.out.println("记录数为:" + recordsCount); System.out.println(shapefile.getShapeType()); // shape类型 //获取字段集合 DBaseField [] dBaseFields=dBaseFile.getFields(); for (int i = 0; i < fieldCount; i++) { System.out.println(dBaseFields[i].getName()); }运行结果如下:
在ArcMap下打开shp文件的属性表,对比可知输出的结果是正确的。
3、获取字段值
// 解析shape文件 try { while (shapefile.hasNext()) { ShapefileRecord record = shapefile.nextRecord(); // 获取一条记录 DBaseRecord dBaseRecord = record.getAttributes(); // 获取该记录的属性信息 Object[] values = dBaseRecord.getValues().toArray();//获取字段值集合 for (int i = 0; i < values.length; i++) { System.out.println(values[i].toString()); } System.out.println("------------------"); } } catch (Exception e) { e.printStackTrace(); System.out.println("解析shapefile文件出错!"); } finally { WWIO.closeStream(shapefile, shpFilePath); WWIO.closeStream(shapefile, shxFilePath); WWIO.closeStream(shapefile, dbfFilePath); WWIO.closeStream(shapefile, prjFilePath); }思路很简单:shapefile文件—>获取一条记录—>获取记录的属性信息-->获取字段值集合。但是有一个问题:不支持中文字段值
调整后运行结果如下:
ArcMap下的属性表如下图所示:
通过对比,发现字段值虽然都读取了,但是顺序却是乱的。目前还未发现是什么原因,下一篇博客再来解决这个问题字段值与字段不对应的问题。下面给出完整的代码:
/** * @方法名称: shapeFileReader ; * @方法描述: 读取sh文件 ; * @参数 :@throws FileNotFoundException * @返回类型: void ; * @创建人:奔跑的鸡丝 ; * @创建时间:2014-12-1 下午12:50:11; * @throws */ private void shapeFileReader() throws FileNotFoundException { String shpFilePath = "D:\\Users\\wwj_data\\states.shp"; String shxFilePath = "D:\\Users\\wwj_data\\states.shx"; String dbfFilePath = "D:\\Users\\wwj_data\\states.dbf"; String prjFilePath = "D:\\Users\\wwj_data\\states.prj"; InputStream shpInputStream = new FileInputStream(shpFilePath); InputStream shxInputStream = new FileInputStream(shxFilePath); InputStream dbfInputStream = new FileInputStream(dbfFilePath); InputStream prjInputStream = new FileInputStream(prjFilePath); // 实例化一个shapefile类 Shapefile shapefile = new Shapefile(shpInputStream, shxInputStream, dbfInputStream, prjInputStream); // 获取shp属性表 DBaseFile dBaseFile = shapefile.getAttributesTable(); int fieldCount = dBaseFile.getNumberOfFields(); // 字段数 int recordsCount = dBaseFile.getNumberOfRecords(); // 记录数 System.out.println("字段数为:" + fieldCount); System.out.println("记录数为:" + recordsCount); System.out.println(shapefile.getShapeType()); // shape类型 //获取字段集合 DBaseField [] dBaseFields=dBaseFile.getFields(); for (int i = 0; i < fieldCount; i++) { System.out.print(dBaseFields[i].getName()+" "); } System.out.println(); // 解析shape文件 try { while (shapefile.hasNext()) { ShapefileRecord record = shapefile.nextRecord(); // 获取一条记录 DBaseRecord dBaseRecord = record.getAttributes(); // 获取该记录的属性信息 Object[] values = dBaseRecord.getValues().toArray();//获取字段值集合 for (int i = 0; i < values.length; i++) { System.out.print(values[i].toString()+" "); } System.out.println("------------------"); } } catch (Exception e) { e.printStackTrace(); System.out.println("解析shapefile文件出错!"); } finally { WWIO.closeStream(shapefile, shpFilePath); WWIO.closeStream(shapefile, shxFilePath); WWIO.closeStream(shapefile, dbfFilePath); WWIO.closeStream(shapefile, prjFilePath); } }
World Wind Java开发之六——解析shape文件(上)
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