abstractdatastore.html

Geotools是一个开源的Java GIS工具包,可利用它来开发符合标准的地理信息系统。Geotools提供了OGC(Open Geospatial Consortium)规范的一个实现来作为他们的

                             <A HREF="../../../org/geotools/feature/SchemaException.html" title="class in org.geotools.feature">SchemaException</A></PRE>
<DL>
<DD><B>Description copied from interface: <CODE><A HREF="../../../org/geotools/data/DataStore.html" title="interface in org.geotools.data">DataStore</A></CODE></B></DD>
<DD>Access a FeatureSource for Query providing a high-level API.
 <p>
 The provided Query does not need to completely cover the existing
 schema for Query.getTypeName(). The result will mostly likely only be
 a FeatureSource and probably wont' allow write access by the
 FeatureStore method.
 </p>
 <p>
 By using Query we allow support for reprojection, in addition
 to overriding the CoordinateSystem used by the native FeatureType.
 </p>
 <p>
 We may wish to limit this method to only support Queries using
 Filter.ALL.
 </p>
 <p>
 Update - GeoServer has an elegatent implementation of this functionality
 that we could steal. GeoServerFeatureSource, GeoServerFeatureStore and
 GeoServerFeatureLocking serve as a working prototype.
 </p>
<P>
<DD><DL>
<DT><B>Specified by:</B><DD><CODE><A HREF="../../../org/geotools/data/DataStore.html#getView(org.geotools.data.Query)">getView</A></CODE> in interface <CODE><A HREF="../../../org/geotools/data/DataStore.html" title="interface in org.geotools.data">DataStore</A></CODE></DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>query</CODE> - Query.getTypeName() locates FeatureType being viewed
<DT><B>Returns:</B><DD>FeatureSource providing opperations for featureType
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></CODE> - If FeatureSource is not available
<DD><CODE><A HREF="../../../org/geotools/feature/SchemaException.html" title="class in org.geotools.feature">SchemaException</A></CODE> - If fetureType is not covered by existing schema</DL>
</DD>
</DL>
<HR>

<A NAME="getFeatureSource(java.lang.String)"><!-- --></A><H3>
getFeatureSource</H3>
<PRE>
public <A HREF="../../../org/geotools/data/FeatureSource.html" title="interface in org.geotools.data">FeatureSource</A> <B>getFeatureSource</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;typeName)
                               throws <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></PRE>
<DL>
<DD>Default implementation based on getFeatureReader and getFeatureWriter.

 <p>
 We should be able to optimize this to only get the RowSet once
 </p>
<P>
<DD><DL>
<DT><B>Specified by:</B><DD><CODE><A HREF="../../../org/geotools/data/DataStore.html#getFeatureSource(java.lang.String)">getFeatureSource</A></CODE> in interface <CODE><A HREF="../../../org/geotools/data/DataStore.html" title="interface in org.geotools.data">DataStore</A></CODE></DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>typeName</CODE> - 
<DT><B>Returns:</B><DD>FeatureSource (or subclass) providing opperations for typeName
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></CODE><DT><B>See Also:</B><DD><A HREF="../../../org/geotools/data/DataStore.html#getFeatureSource(java.lang.String)"><CODE>DataStore.getFeatureSource(java.lang.String)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getFeatureReader(org.geotools.data.Query, org.geotools.data.Transaction)"><!-- --></A><H3>
getFeatureReader</H3>
<PRE>
public <A HREF="../../../org/geotools/data/FeatureReader.html" title="interface in org.geotools.data">FeatureReader</A> <B>getFeatureReader</B>(<A HREF="../../../org/geotools/data/Query.html" title="interface in org.geotools.data">Query</A>&nbsp;query,
                                      <A HREF="../../../org/geotools/data/Transaction.html" title="interface in org.geotools.data">Transaction</A>&nbsp;transaction)
                               throws <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></PRE>
<DL>
<DD><B>Description copied from interface: <CODE><A HREF="../../../org/geotools/data/DataStore.html" title="interface in org.geotools.data">DataStore</A></CODE></B></DD>
<DD>Access a FeatureReader providing access to Feature information.

 <p>
 <b>Filter</b> is used as a low-level indication of constraints.
 (Implementations may resort to using a FilteredFeatureReader, or
 provide their own optimizations)
 </p>

 <p>
 <b>FeatureType</b> provides a template for the returned FeatureReader
 </p>

 <ul>
 <li>
 featureType.getTypeName(): used by JDBC as the table reference to query
 against. Shapefile reader may need to store a lookup to the required
 filename.
 </li>
 <li>
 featureType.getAttributeTypes(): describes the requested content. This
 may be a subset of the complete FeatureType defined by the DataStore.
 </li>
 <li>
 getType.getNamespace(): describes the requested namespace for the
 results (may be different then the one used internally)
 </li>
 </ul>

 <p>
 <b>Transaction</b> to externalize DataStore state on a per Transaction
 basis. The most common example is a JDBC datastore saving a Connection
 for use across several FeatureReader requests. Similarly a Shapefile
 reader may wish to redirect FeatureReader requests to a alternate
 filename over the course of a Transaction.
 </p>

 <p>
 <b>Notes For Implementing DataStore</b>
 </p>

 <p>
 Subclasses may need to retrieve additional attributes, beyond those
 requested by featureType.getAttributeTypes(), in order to correctly
 apply the <code>filter</code>.<br>
 These Additional <b>attribtues</b> should be not be returned by
 FeatureReader. Subclasses may use ReTypeFeatureReader to aid in
 acomplishing this.
 </p>
 <p>
 Helper classes for implementing a FeatureReader (in order):
 </p>
 <ul>
 <li>
 DefaultFeatureReader
 - basic support for creating a FeatureReader for an AttributeReader
 </li>
 <li>
 FilteringFeatureReader
 - filtering support
 </li>
 <li>
 DiffFeatureReader
 - In-Process Transaction Support (see TransactionStateDiff)
 </li>
 <li>
 ReTypeFeatureReader
 - Feature Type schema manipulation of namesspace and attribute type subsets
 </li>
 <li>
 EmptyFeatureReader
 - provides no content for Filter.ALL optimizations
 </li>
 </ul>
 <p>
 Sample use (not optimized):
 </p>
 <pre><code>
 if (filter == Filter.ALL) {
      return new EmptyFeatureReader(featureType);
  }

  String typeName = featureType.getTypeName();
  FeatureType schema = getSchema( typeName );
  FeatureReader reader = new DefaultFeatureReader( getAttributeReaders(), schema );

  if (filter != Filter.NONE) {
      reader = new FilteringFeatureReader(reader, filter);
  }

  if (transaction != Transaction.AUTO_COMMIT) {
      Map diff = state(transaction).diff(typeName);
      reader = new DiffFeatureReader(reader, diff);
  }

  if (!featureType.equals(reader.getFeatureType())) {
      reader = new ReTypeFeatureReader(reader, featureType);
  }
 return reader
 </code></pre>
 <p>
 Locking support does not need to be provided for FeatureReaders.
 </p>
<P>
<DD><DL>
<DT><B>Specified by:</B><DD><CODE><A HREF="../../../org/geotools/data/DataStore.html#getFeatureReader(org.geotools.data.Query, org.geotools.data.Transaction)">getFeatureReader</A></CODE> in interface <CODE><A HREF="../../../org/geotools/data/DataStore.html" title="interface in org.geotools.data">DataStore</A></CODE></DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>query</CODE> - Requested form of the returned Features and the filter used
              to constraints the results<DD><CODE>transaction</CODE> - Transaction this query opperates against
<DT><B>Returns:</B><DD>FeatureReader Allows Sequential Processing of featureType
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></CODE></DL>
</DD>
</DL>
<HR>

<A NAME="getFeatureReader(java.lang.String, org.geotools.data.Query)"><!-- --></A><H3>
getFeatureReader</H3>
<PRE>
protected <A HREF="../../../org/geotools/data/FeatureReader.html" title="interface in org.geotools.data">FeatureReader</A> <B>getFeatureReader</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;typeName,
                                         <A HREF="../../../org/geotools/data/Query.html" title="interface in org.geotools.data">Query</A>&nbsp;query)
                                  throws <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></PRE>
<DL>
<DD>GR: this method is called from inside getFeatureReader(Query ,Transaction )
 to allow subclasses return an optimized FeatureReader wich supports the
 filter and attributes truncation specified in <code>query</code>
 <p>
 A subclass that supports the creation of such an optimized FeatureReader
 shold override this method. Otherwise, it just returns
 <code>getFeatureReader(typeName)</code>
 <p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></CODE></DL>
</DD>
</DL>
<HR>

<A NAME="getUnsupportedFilter(java.lang.String, org.geotools.filter.Filter)"><!-- --></A><H3>
getUnsupportedFilter</H3>
<PRE>
protected <A HREF="../../../org/geotools/filter/Filter.html" title="interface in org.geotools.filter">Filter</A> <B>getUnsupportedFilter</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;typeName,
                                      <A HREF="../../../org/geotools/filter/Filter.html" title="interface in org.geotools.filter">Filter</A>&nbsp;filter)</PRE>
<DL>
<DD>GR: if a subclass supports filtering, it should override this method
 to return the unsupported part of the passed filter, so a
 FilteringFeatureReader will be constructed upon it. Otherwise it will
 just return the same filter.
 <p>
 If the complete filter is supported, the subclass must return <code>Filter.NONE</code>
 </p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
</DL>
</DD>
</DL>
<HR>

<A NAME="getFeatureWriter(java.lang.String, org.geotools.filter.Filter, org.geotools.data.Transaction)"><!-- --></A><H3>
getFeatureWriter</H3>
<PRE>
public <A HREF="../../../org/geotools/data/FeatureWriter.html" title="interface in org.geotools.data">FeatureWriter</A> <B>getFeatureWriter</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;typeName,
                                      <A HREF="../../../org/geotools/filter/Filter.html" title="interface in org.geotools.filter">Filter</A>&nbsp;filter,
                                      <A HREF="../../../org/geotools/data/Transaction.html" title="interface in org.geotools.data">Transaction</A>&nbsp;transaction)
                               throws <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/IOException.html" title="class or interface in java.io">IOException</A></PRE>
<DL>
<DD><B>Description copied from interface: <CODE><A HREF="../../../org/geotools/data/DataStore.html" title="interface in org.geotools.data">DataStore</A></CODE></B></DD>
<DD>Access FeatureWriter for modification of existing DataStore contents.

 <p>
 To limit FeatureWriter to the FeatureTypes defined by this DataStore,
 typeName is used to indicate FeatureType. The resulting
 feature writer will allow modifications against the
 same FeatureType provided by getSchema( typeName )