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

 </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>Specified by:</B><DD><CODE><A HREF="../../../org/geotools/data/DataStore.html#getFeatureWriter(java.lang.String, org.geotools.filter.Filter, org.geotools.data.Transaction)">getFeatureWriter</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> - 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><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 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>Specified by:</B><DD><CODE><A HREF="../../../org/geotools/data/DataStore.html#getFeatureWriter(java.lang.String, org.geotools.data.Transaction)">getFeatureWriter</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> - 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><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>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>Specified by:</B><DD><CODE><A HREF="../../../org/geotools/data/DataStore.html#getFeatureWriterAppend(java.lang.String, org.geotools.data.Transaction)">getFeatureWriterAppend</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> - 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>Locking manager used for this DataStore.

 <p>
 By default AbstractDataStore makes use of InProcessLockingManager.
 </p>
<P>
<DD><DL>
<DT><B>Specified by:</B><DD><CODE><A HREF="../../../org/geotools/data/DataStore.html#getLockingManager()">getLockingManager</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>Returns:</B><DD>DataStores may return <code>null</code>, if the handling locking
         in another fashion.<DT><B>See Also:</B><DD><A HREF="../../../org/geotools/data/DataStore.html#getLockingManager()"><CODE>DataStore.getLockingManager()</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getBounds(org.geotools.data.Query)"><!-- --></A><H3>
getBounds</H3>
<PRE>
protected <A HREF="http://www.jump-project.org/docs/jts/1.7/api/com/vividsolutions/jts/geom/Envelope.html" title="class or interface in com.vividsolutions.jts.geom">Envelope</A> <B>getBounds</B>(<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>Computes the bounds of the features for the specified feature type that
 satisfy the query provided that there is a fast way to get that result.
 <p>
 Will return null if there is not fast way to compute the bounds. Since
 it's based on some kind of header/cached information, it's not guaranteed
 to be real bound of the features
 </p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>query</CODE> - 
<DT><B>Returns:</B><DD>the bounds, or null if too expensive
<DT><B>Throws:</B>
<DD><CODE><A HREF="../../../org/geotools/data/SchemaNotFoundException.html" title="class in org.geotools.data">SchemaNotFoundException</A></CODE>
<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="getCount(org.geotools.data.Query)"><!-- --></A><H3>
getCount</H3>
<PRE>
protected int <B>getCount</B>(<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>Gets the number of the features that would be returned by this query for
 the specified feature type.
 <p>
 If getBounds(Query) returns <code>-1</code> due to expense consider
 using <code>getFeatures(Query).getCount()</code> as a an alternative.
 </p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>query</CODE> - Contains the Filter and MaxFeatures to find the bounds for.
<DT><B>Returns:</B><DD>The number of Features provided by the Query or <code>-1</code>
         if count is too expensive to calculate or any errors or occur.
<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>
<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 there are errors getting the count</DL>
</DD>
</DL>
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