datastore.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

 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>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="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>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 )
 </p>

 <p>
 The FeatureWriter will provide access to the existing contents of the
 FeatureType referenced by typeName. The provided filter will be used
 to skip over Features as required.
 </p>

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

 <p>
 The returned FeatureWriter <b>does not</b> support the addition of new
 Features to FeatureType (it would need to police your modifications to
 agree with <code>filer</code>).  As such it will return
 <code>false</code> for getNext() when it reaches the end of the Query
 and NoSuchElementException when next() is called.
 </p>

 <p>
 Helper classes for implementing a FeatureWriter (in order):
 </p>
 <li>
 InProcessLockingManager.checkedWriter( writer )
 - provides a check against locks before allowing modification

 <li>
 FilteringFeatureWriter
 - filtering support for FeatureWriter (does not allow new content)
 </li>
 <li>
 DiffFeatureWriter
 - In-Process Transaction Support (see TransactionStateDiff)
 </li>
 <li>
 EmptyFeatureWriter
 - provides no content for Filter.ALL optimizations
 </li>
 </ul>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>typeName</CODE> - Indicates featureType to be modified<DD><CODE>filter</CODE> - constraints used to limit the modification<DD><CODE>transaction</CODE> - Transaction this query opperates against
<DT><B>Returns:</B><DD>FeatureWriter Allows Sequential Modification 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="getFeatureWriter(java.lang.String, 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/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>Access FeatureWriter for modification of the DataStore typeName.

 <p>
 FeatureWriters will need to be limited to the FeatureTypes defined by
 the DataStore, the easiest way to express this limitation is to the
 FeatureType by a provided typeName.
 </p>

 <p>
 The returned FeatureWriter will return <code>false</code> for getNext()
 when it reaches the end of the Query.
 </p>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>typeName</CODE> - Indicates featureType to be modified<DD><CODE>transaction</CODE> - Transaction to 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="getFeatureWriterAppend(java.lang.String, org.geotools.data.Transaction)"><!-- --></A><H3>
getFeatureWriterAppend</H3>
<PRE>
public <A HREF="../../../org/geotools/data/FeatureWriter.html" title="interface in org.geotools.data">FeatureWriter</A> <B>getFeatureWriterAppend</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/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>Aquire a FeatureWriter for adding new content to a FeatureType.

 <p>
 This FeatureWriter will return <code>false</code> for hasNext(), however
 next() may be used to aquire new Features that may be writen out to add
 new content.
 </p>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>typeName</CODE> - Indicates featureType to be modified<DD><CODE>transaction</CODE> - Transaction to opperates against
<DT><B>Returns:</B><DD>FeatureWriter that may only be used to append new content
<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="getLockingManager()"><!-- --></A><H3>
getLockingManager</H3>
<PRE>
public <A HREF="../../../org/geotools/data/LockingManager.html" title="interface in org.geotools.data">LockingManager</A> <B>getLockingManager</B>()</PRE>
<DL>
<DD>Retrieve a per featureID based locking service from this DataStore.

 <p>
 It is common to return an instanceof InProcessLockingManager for
 DataStores that do not provide native locking.
 </p>

 <p>
 AbstractFeatureLocking makes use of this service to provide locking
 support. You are not limitied by this implementation and may simply
 return <code>null</code> for this value.
 </p>
<P>
<DD><DL>

<DT><B>Returns:</B><DD>DataStores may return <code>null</code>, if the handling locking
         in another fashion.</DL>
</DD>
</DL>
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