| org.apache.cocoon.reading.AbstractReader
 org.apache.cocoon.reading.ServiceableReader
org.apache.cocoon.reading.DatabaseReader
| DatabaseReader | | public class DatabaseReader extends ServiceableReader implements Configurable,Disposable,CacheableProcessingComponent(Code) | | This Reader pulls a resource from a database. It is configured with
the Connection to use, parameters specify the table and column
to pull the image from, and source specifies the source key information.
author:
Berin Loritsch
version:
CVS $Id: DatabaseReader.java 452159 2006-10-02 18:20:45Z vgritsenko $ |
| Method Summary | |
| public void | configure(Configuration conf)
Configure the Reader so that we can use the same database
for all instances. | | public void | dispose()
| | public void | generate()
Generates the resource we need to retrieve verbatim from the
database. | | public java.io.Serializable | getKey()
Generate the unique key. | | public String | getMimeType()
| | protected String | getQuery()
This method builds the query string used for accessing the database. | | public SourceValidity | getValidity()
Generate the validity object. | | protected boolean | modifiedSince(ResultSet set, Request request, Response response)
Tests whether a resource has been modified or not. | | public void | recycle()
| | public void | serialize(Response response)
This method actually performs the serialization. | | public void | service(ServiceManager manager)
| | public void | setup(SourceResolver resolver, Map objectModel, String src, Parameters par)
Set the SourceResolver the object model Map,
the source and sitemap Parameters used to process the request. |
| configure | | public void configure(Configuration conf) throws ConfigurationException(Code) | | Configure the Reader so that we can use the same database
for all instances.
|
| dispose | | public void dispose()(Code) | | |
| generate | | public void generate() throws ProcessingException, SAXException, IOException(Code) | | Generates the resource we need to retrieve verbatim from the
database. Granted, this can be used for any resource from a
database, so we may want to get rid of the bias toward images.
This reader requires a number of parameters:
<parameter name="table" value="database_table_name"/>
<parameter name="image" value="database_resource_column_name"/>
<parameter name="key" value="database_lookup_key_column_name"/>
Please note that if any of those parameters are missing, this
Reader cannot function. There are a number of other
parameters that allow you to provide hints for the reader to
optimize resource use:
<parameter name="last-modified" value="database_timestamp_column_name"/>
<parameter name="content-type" value="content_mime_type"/>
<parameter name="type-column" value="database_content_mime_type_column"/>
<parameter name="expires" value="number_of_millis_before_refresh"/>
<parameter name="where" value="alternate_key = 'foo'"/>
<parameter name="order-by" value="alternate_key DESC"/>
Lastly, the key value is derived from the value of
the source string.
|
| getKey | | public java.io.Serializable getKey()(Code) | | Generate the unique key.
This key must be unique inside the space of this component.
The generated key hashes the src |
| getQuery | | protected String getQuery() throws ProcessingException(Code) | | This method builds the query string used for accessing the database.
If the required parameters do not exist, then we cannot build a
correct query.
|
| getValidity | | public SourceValidity getValidity()(Code) | | Generate the validity object.
The generated validity object or null if thecomponent is currently not cacheable. |
| modifiedSince | | protected boolean modifiedSince(ResultSet set, Request request, Response response) throws SQLException(Code) | | Tests whether a resource has been modified or not. As Blobs and
database columns usually do not have intrinsic dates on them (at
least easily accessible), we have to have a database column that
holds a date for the resource. Please note, that the database
column must be a Timestamp column.
In the absence of such a column this method always
returns true. This is because databases are much
more prone to change than filesystems, and don't have intrinsic
timestamps on column updates.
|
| recycle | | public void recycle()(Code) | | |
| service | | public void service(ServiceManager manager) throws ServiceException(Code) | | |
| Fields inherited from org.apache.cocoon.reading.ServiceableReader | protected ServiceManager manager(Code)(Java Doc)
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| Methods inherited from org.apache.cocoon.reading.ServiceableReader | public void service(ServiceManager manager) throws ServiceException(Code)(Java Doc)
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