daveb 01/04/19 21:25:29
Added: contrib/temporary/enhydra-velocity/src/com/miceda/velsrv/vpo
VelocityPO.java VelocityService.java
Log:
Example of using Velocity with Enhydra
Revision Changes Path
1.1
jakarta-velocity/contrib/temporary/enhydra-velocity/src/com/miceda/velsrv/vpo/VelocityPO.java
Index: VelocityPO.java
===================================================================
package com.miceda.velsrv.vpo;
// Java
import java.io.*;
// Enhydra
import com.lutris.appserver.server.Enhydra;
import com.lutris.logging.Logger;
import com.lutris.appserver.server.httpPresentation.HttpPresentation;
import com.lutris.appserver.server.httpPresentation.HttpPresentationComms;
import com.lutris.appserver.server.httpPresentation.HttpPresentationException;
// Velocity
import org.apache.velocity.VelocityContext;
/**
* Extend this class for presentation instead of implementing
* the HttpPresentation interface.
* <br>
* This is not optimized, but its a start.
*
* @author <a href="mailto:[EMAIL PROTECTED]">Dave Bryson</a>
* @version 1.0
* @since 1.0
* @see HttpPresentation
*/
public abstract class VelocityPO implements HttpPresentation
{
/**
* Override and populate the context.
* see the WelcomePresentation example
*
* @param comms a <code>HttpPresentationComms</code> value
* @param context a <code>VelocityContext</code> value
* @return a <code>String</code> value
* @exception Exception if an error occurs
*/
protected abstract String processRequest( HttpPresentationComms comms,
VelocityContext context )
throws Exception;
/**
* Call this to return the processed template.
*
* @param context a <code>VelocityContext</code> value
* @param filename a <code>String</code> value
* @return a <code>String</code> value
* @exception Exception if an error occurs
*/
protected String getOutput( VelocityContext context, String filename )
throws Exception
{
return VelocityService.getInstance().handleRequest(context,filename);
}
/**
* Implements the run method required by the HttpPresentation.
* You do not need to use this method.
*
* @param comms a <code>HttpPresentationComms</code> value
* @exception Exception if an error occurs
*/
public void run( HttpPresentationComms comms )
throws Exception
{
String outputString = null;
try
{
outputString = processRequest( comms, doSetupContext(comms) );
}
catch( Exception e )
{
outputString = error(e.getMessage());
Enhydra.getLogChannel().write( Logger.ERROR, "Error processing template
" + e );
}
finally
{
if( outputString == null )
{
String errorMessage =
"Output set to null. Did you set the template filename?";
doOutput( comms, error(errorMessage) );
}
else
{
doOutput( comms, outputString );
}
}
}
/**
* Setup the context. Note, this automatically makes
* the HttpPresentationComms available to your templates
*
* @param comms a <code>HttpPresentationComms</code> value
* @return a <code>VelocityContext</code> value
*/
private VelocityContext doSetupContext( HttpPresentationComms comms )
{
VelocityContext ctx = getContext();
ctx.put("comms", comms );
return ctx;
}
/**
* Get the context from the Service
*
* @return a <code>VelocityContext</code> value
*/
private VelocityContext getContext()
{
return VelocityService.getInstance().getContext();
}
/**
* Write out the populated template to the HttpPresentationComms
*
* @param comms a <code>HttpPresentationComms</code> value
* @param outty a <code>String</code> value
* @exception Exception if an error occurs
*/
private void doOutput( HttpPresentationComms comms, String outty )
throws Exception
{
comms.response.writeHTML( outty );
}
/**
* Returns a default error message if the template was not found.
*
* @param message a <code>String</code> value
* @return a <code>String</code> value
*/
private final String error( String message )
{
StringBuffer html = new StringBuffer();
html.append("<html>");
html.append("<body bgcolor=\"#ffffff\">");
html.append("<h2>Error processing the template</h2>");
html.append(message);
html.append("</body>");
html.append("</html>");
return html.toString();
}
}
1.1
jakarta-velocity/contrib/temporary/enhydra-velocity/src/com/miceda/velsrv/vpo/VelocityService.java
Index: VelocityService.java
===================================================================
package com.miceda.velsrv.vpo;
// Java
import java.io.*;
import java.util.Properties;
// Enhydra imports
import com.lutris.util.Config;
import com.lutris.logging.Logger;
import com.lutris.appserver.server.Enhydra;
// Velocity
import org.apache.velocity.Template;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.runtime.Runtime;
import org.apache.velocity.io.VelocityWriter;
import org.apache.velocity.util.SimplePool;
import org.apache.velocity.context.Context;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.exception.ParseErrorException;
/**
* Singleton Velocity service.
* Processes the template and makes the information you put in the context
* available to the template.
*
* You can init() this in the startUp() method of your Application.
*
* @author <a href="mailto:[EMAIL PROTECTED]">Dave Bryson</a>
* @version 1.0
* @since 1.0
*/
public class VelocityService
{
// My single instance
private static VelocityService instance =
new VelocityService();
private static boolean isInited = false;
/**
* Encoding determined from the velocity.properties file.
*/
private String encoding;
private String defaultContentType;
/**
* The HTTP content type context key.
*/
public static final String CONTENT_TYPE = "default.contentType";
/**
* The default content type for the response
*/
public static final String DEFAULT_CONTENT_TYPE = "text/html";
/**
* Encoding for the output stream
*/
public static final String DEFAULT_OUTPUT_ENCODING = "ISO-8859-1";
/**
* Private constructor
*/
private VelocityService()
{}
/**
* Start up the service and load the velocity properties file.
*
* @param cf a <code>Config</code> value
* @exception Exception if an error occurs
*/
public void init( Config cf ) throws Exception
{
String vel_props = cf.getString("velocity");
try
{
Properties p = new Properties();
p.load( new FileInputStream(vel_props) );
Velocity.init(p);
defaultContentType = Runtime.getString( CONTENT_TYPE,
DEFAULT_CONTENT_TYPE);
encoding = Runtime.getString( Runtime.OUTPUT_ENCODING,
DEFAULT_OUTPUT_ENCODING);
setInitValue(true);
}
catch( Exception e )
{
Enhydra.getLogChannel().write(Logger.ERROR, "Error init() velocity
service" + e );
throw new Exception("Error on init()");
}
}
private void setInitValue( boolean v )
{
this.isInited = v;
}
/**
* Create a Context object that also contains the globalContext.
*
* @return A Context object.
*/
public VelocityContext getContext()
{
return new VelocityContext();
}
/**
* Return a template from Velocity.
*
* @param filename A String with the name of the template.
* @return A Template.
* @exception NotFoundException.
*/
private Template getTemplate( String name )
throws Exception
{
return Runtime.getTemplate(name);
}
/**
* Process the template.
*
* @param context a <code>Context</code> value
* @param filename a <code>String</code> value
* @return a <code>String</code> value
* @exception Exception if an error occurs
*/
public String handleRequest(Context context, String filename)
throws Exception
{
String results = null;
ByteArrayOutputStream bytes = null;
try
{
bytes = new ByteArrayOutputStream();
handleRequest(context, filename, bytes);
results = bytes.toString(encoding);
}
catch(Exception e)
{
renderingError(filename, e);
}
finally
{
try
{
if (bytes != null) bytes.close();
}
catch(IOException ignored)
{
}
}
return results;
}
/**
* Process the request and fill in the template with the values
* you set in the Context.
*
* @param context A Context.
* @param filename A String with the filename of the template.
* @param out A OutputStream where we will write the process template as
* a String.
*
* @throws TurbineException Any exception trown while processing will be
* wrapped into a TurbineException and rethrown.
*/
private void handleRequest(Context context,
String filename,
OutputStream output)
throws Exception
{
OutputStreamWriter writer = null;
try
{
writer = new OutputStreamWriter(output, encoding);
Template template = getTemplate(filename);
template.merge( context, writer );
}
catch(Exception e)
{
renderingError(filename, e);
}
finally
{
try
{
if (writer != null)
{
writer.flush();
}
}
catch (Exception e)
{
// do nothing
}
}
}
/**
* Macro to handle rendering errors.
*
* @param filename The file name of the unrenderable template.
* @param e The error.
*
* @exception TurbineException Thrown every time. Adds additional
* information to <code>e</code>.
*/
private static final void renderingError(String filename, Exception e)
throws Exception
{
String err = "Error rendering Velocity template: " + filename;
Enhydra.getLogChannel().write(Logger.ERROR, err + ": " + e.getMessage());
throw new Exception(e.getMessage());
}
/**
* @return a <code>VelocityService</code> my only instance
*/
public static VelocityService getInstance()
{
return instance;
}
}
