org.apache.velocity.servlet
Class VelocityServlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          org.apache.velocity.servlet.VelocityServlet

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

Deprecated. This servlet has been replaced by VelocityViewServlet, available from the Velocity-Tools sub-project. VelocityViewServlet provides support for quick, clean MVC web development. VelocityServlet will be removed in a future version of Velocity.

public abstract class VelocityServlet
extends HttpServlet

Base class which simplifies the use of Velocity with Servlets. Extend this class, implement the handleRequest() method, and add your data to the context. Then call getTemplate("myTemplate.wm"). This class puts some things into the context object that you should be aware of:

 "req" - The HttpServletRequest object
 "res" - The HttpServletResponse object
 

There are other methods you can override to access, alter or control any part of the request processing chain. Please see the javadocs for more information on :

• loadConfiguration() : for setting up the Velocity runtime
• createContext() : for creating and loading the Context
• setContentType() : for changing the content type on a request by request basis
• handleRequest() : you must implement this
• mergeTemplate() : the template rendering process
• requestCleanup() : post rendering resource or other cleanup
• error() : error handling

If you put a String with key "contentType" object into the context within either your servlet or within your template, then that will be used to override the default content type specified in the properties file.

Author:

Dave Bryson, Jon S. Stevens, Geir Magnusson Jr., Kent Johnson, Daniel Rall $Id: VelocityServlet.java 463298 2006-10-12 16:10:32Z henning $

See Also:

Serialized Form

Field Summary

static String	CONTENT_TYPE Deprecated. The HTTP content type context key.
static String	DEFAULT_CONTENT_TYPE Deprecated. The default content type for the response
static String	DEFAULT_OUTPUT_ENCODING Deprecated. Encoding for the output stream
protected static String	INIT_PROPS_KEY Deprecated. This is the string that is looked for when getInitParameter is called (org.apache.velocity.properties).
static String	REQUEST Deprecated. The context key for the HTTP request object.
static String	RESPONSE Deprecated. The context key for the HTTP response object.

Constructor Summary

VelocityServlet()
Deprecated.

Method Summary

protected String	chooseCharacterEncoding(HttpServletRequest request) Deprecated. Chooses the output character encoding to be used as the value for the "charset=" portion of the HTTP Content-Type header (and thus returned by response.getCharacterEncoding()).
protected Context	createContext(HttpServletRequest request, HttpServletResponse response) Deprecated. Returns a context suitable to pass to the handleRequest() method Default implementation will create a VelocityContext object, put the HttpServletRequest and HttpServletResponse into the context accessable via the keys VelocityServlet.REQUEST and VelocityServlet.RESPONSE, respectively.
void	doGet(HttpServletRequest request, HttpServletResponse response) Deprecated. Handles HTTP GET requests by calling doRequest(HttpServletRequest, HttpServletResponse).
void	doPost(HttpServletRequest request, HttpServletResponse response) Deprecated. Handles HTTP POST requests by calling doRequest(HttpServletRequest, HttpServletResponse).
protected void	doRequest(HttpServletRequest request, HttpServletResponse response) Deprecated. Handles all requests (by default).
protected void	error(HttpServletRequest request, HttpServletResponse response, Exception cause) Deprecated. Invoked when there is an error thrown in any part of doRequest() processing.
Template	getTemplate(String name) Deprecated. Retrieves the requested template.
Template	getTemplate(String name, String encoding) Deprecated. Retrieves the requested template with the specified character encoding.
protected Template	handleRequest(Context ctx) Deprecated. Use handleRequest( HttpServletRequest request, HttpServletResponse response, Context ctx )
protected Template	handleRequest(HttpServletRequest request, HttpServletResponse response, Context ctx) Deprecated. Implement this method to add your application data to the context, calling the getTemplate() method to produce your return value.
void	init(ServletConfig config) Deprecated. Performs initialization of this servlet.
protected void	initVelocity(ServletConfig config) Deprecated. Initializes the Velocity runtime, first calling loadConfiguration(ServletConvig) to get a java.util.Properties of configuration information and then calling Velocity.init().
protected Properties	loadConfiguration(ServletConfig config) Deprecated. Use VelocityViewServlet from the Velocity Tools library instead.
protected void	mergeTemplate(Template template, Context context, HttpServletResponse response) Deprecated. merges the template with the context.
protected void	requestCleanup(HttpServletRequest request, HttpServletResponse response, Context context) Deprecated. A cleanup routine which is called at the end of the doRequest(HttpServletRequest, HttpServletResponse) processing sequence, allowing a derived class to do resource cleanup or other end of process cycle tasks.
protected void	setContentType(HttpServletRequest request, HttpServletResponse response) Deprecated. Sets the content type of the response, defaulting to defaultContentType if not overriden.

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

REQUEST

public static final String REQUEST

Deprecated.

The context key for the HTTP request object.

See Also:

Constant Field Values

RESPONSE

public static final String RESPONSE

Deprecated.

The context key for the HTTP response object.

See Also:

Constant Field Values

CONTENT_TYPE

public static final String CONTENT_TYPE

Deprecated.

The HTTP content type context key.

See Also:

Constant Field Values

DEFAULT_CONTENT_TYPE

public static final String DEFAULT_CONTENT_TYPE

Deprecated.

The default content type for the response

See Also:

Constant Field Values

DEFAULT_OUTPUT_ENCODING

public static final String DEFAULT_OUTPUT_ENCODING

Deprecated.

Encoding for the output stream

See Also:

Constant Field Values

INIT_PROPS_KEY

protected static final String INIT_PROPS_KEY

Deprecated.

This is the string that is looked for when getInitParameter is called (org.apache.velocity.properties).

See Also:

Constant Field Values

Constructor Detail

VelocityServlet

public VelocityServlet()

Deprecated.

Method Detail

init

public void init(ServletConfig config)
          throws ServletException

Deprecated.

Performs initialization of this servlet. Called by the servlet container on loading.

Specified by:

init in interface Servlet

Overrides:

init in class GenericServlet

Parameters:

config - The servlet configuration to apply.

Throws:

ServletException

initVelocity

protected void initVelocity(ServletConfig config)
                     throws ServletException

Deprecated.

Initializes the Velocity runtime, first calling loadConfiguration(ServletConvig) to get a java.util.Properties of configuration information and then calling Velocity.init(). Override this to do anything to the environment before the initialization of the singelton takes place, or to initialize the singleton in other ways.

Parameters:

config -

Throws:

ServletException

loadConfiguration

protected Properties loadConfiguration(ServletConfig config)
                                throws IOException,
                                       FileNotFoundException

Deprecated. Use VelocityViewServlet from the Velocity Tools library instead.

Loads the configuration information and returns that information as a Properties, which will be used to initialize the Velocity runtime.

Currently, this method gets the initialization parameter VelocityServlet.INIT_PROPS_KEY, which should be a file containing the configuration information.

To configure your Servlet Spec 2.2 compliant servlet runner to pass this to you, put the following in your WEB-INF/web.xml file

    <servlet>
      <servlet-name> YourServlet </servlet-name>
      <servlet-class> your.package.YourServlet </servlet-class>
      <init-param>
         <param-name> org.apache.velocity.properties </param-name>
         <param-value> velocity.properties </param-value>
      </init-param>
    </servlet>
   

Alternately, if you wish to configure an entire context in this fashion, you may use the following:

    <context-param>
       <param-name> org.apache.velocity.properties </param-name>
       <param-value> velocity.properties </param-value>
       <description> Path to Velocity configuration </description>
    </context-param>
   

Derived classes may do the same, or take advantage of this code to do the loading for them via :

      Properties p = super.loadConfiguration( config );
   

and then add or modify the configuration values from the file.

Parameters:

config - ServletConfig passed to the servlets init() function Can be used to access the real path via ServletContext (hint)

Returns:

java.util.Properties loaded with configuration values to be used to initialize the Velocity runtime.

Throws:

FileNotFoundException - if a specified file is not found.

IOException - I/O problem accessing the specified file, if specified.

doGet

public void doGet(HttpServletRequest request,
                  HttpServletResponse response)
           throws ServletException,
                  IOException

Deprecated.

Handles HTTP GET requests by calling doRequest(HttpServletRequest, HttpServletResponse).

Overrides:

doGet in class HttpServlet

Parameters:

request -

response -

Throws:

ServletException

IOException

doPost

public void doPost(HttpServletRequest request,
                   HttpServletResponse response)
            throws ServletException,
                   IOException

Deprecated.

Handles HTTP POST requests by calling doRequest(HttpServletRequest, HttpServletResponse).

Overrides:

doPost in class HttpServlet

Parameters:

request -

response -

Throws:

ServletException

IOException

doRequest

protected void doRequest(HttpServletRequest request,
                         HttpServletResponse response)
                  throws ServletException,
                         IOException

Deprecated.

Handles all requests (by default).

Parameters:

request - HttpServletRequest object containing client request

response - HttpServletResponse object for the response

Throws:

ServletException

IOException

requestCleanup

protected void requestCleanup(HttpServletRequest request,
                              HttpServletResponse response,
                              Context context)

Deprecated.

A cleanup routine which is called at the end of the doRequest(HttpServletRequest, HttpServletResponse) processing sequence, allowing a derived class to do resource cleanup or other end of process cycle tasks.

Parameters:

request - servlet request from client

response - servlet reponse

context - context created by the createContext() method

mergeTemplate

protected void mergeTemplate(Template template,
                             Context context,
                             HttpServletResponse response)
                      throws ResourceNotFoundException,
                             ParseErrorException,
                             MethodInvocationException,
                             IOException,
                             UnsupportedEncodingException,
                             Exception

Deprecated.

merges the template with the context. Only override this if you really, really really need to. (And don't call us with questions if it breaks :)

Parameters:

template - template object returned by the handleRequest() method

context - context created by the createContext() method

response - servlet reponse (use this to get the output stream or Writer

Throws:

ResourceNotFoundException

ParseErrorException

MethodInvocationException

IOException

UnsupportedEncodingException

Exception

setContentType

protected void setContentType(HttpServletRequest request,
                              HttpServletResponse response)

Deprecated.

Sets the content type of the response, defaulting to defaultContentType if not overriden. Delegates to chooseCharacterEncoding(HttpServletRequest) to select the appropriate character encoding.

Parameters:

request - The servlet request from the client.

response - The servlet reponse to the client.

chooseCharacterEncoding

protected String chooseCharacterEncoding(HttpServletRequest request)

Deprecated.

Chooses the output character encoding to be used as the value for the "charset=" portion of the HTTP Content-Type header (and thus returned by response.getCharacterEncoding()). Called by setContentType(HttpServletRequest, HttpServletResponse) if an encoding isn't already specified by Content-Type. By default, chooses the value of RuntimeSingleton's output.encoding property.

Parameters:

request - The servlet request from the client.

Returns:

The chosen character encoding.

createContext

protected Context createContext(HttpServletRequest request,
                                HttpServletResponse response)

Deprecated.

Returns a context suitable to pass to the handleRequest() method

Default implementation will create a VelocityContext object, put the HttpServletRequest and HttpServletResponse into the context accessable via the keys VelocityServlet.REQUEST and VelocityServlet.RESPONSE, respectively.

Parameters:

request - servlet request from client

response - servlet reponse to client

Returns:

context

getTemplate

public Template getTemplate(String name)
                     throws ResourceNotFoundException,
                            ParseErrorException,
                            Exception

Deprecated.

Retrieves the requested template.

Parameters:

name - The file name of the template to retrieve relative to the template root.

Returns:

The requested template.

Throws:

ResourceNotFoundException - if template not found from any available source.

ParseErrorException - if template cannot be parsed due to syntax (or other) error.

Exception - if an error occurs in template initialization

getTemplate

public Template getTemplate(String name,
                            String encoding)
                     throws ResourceNotFoundException,
                            ParseErrorException,
                            Exception

Deprecated.

Retrieves the requested template with the specified character encoding.

Parameters:

name - The file name of the template to retrieve relative to the template root.

encoding - the character encoding of the template

Returns:

The requested template.

Throws:

ResourceNotFoundException - if template not found from any available source.

ParseErrorException - if template cannot be parsed due to syntax (or other) error.

Exception - if an error occurs in template initialization

Since:

Velocity v1.1

handleRequest

protected Template handleRequest(HttpServletRequest request,
                                 HttpServletResponse response,
                                 Context ctx)
                          throws Exception

Deprecated.

Implement this method to add your application data to the context, calling the getTemplate() method to produce your return value.

In the event of a problem, you may handle the request directly and return null or throw a more meaningful exception for the error handler to catch.

Parameters:

request - servlet request from client

response - servlet reponse

ctx - The context to add your data to.

Returns:

The template to merge with your context or null, indicating that you handled the processing.

Throws:

Exception

Since:

Velocity v1.1

handleRequest

protected Template handleRequest(Context ctx)
                          throws Exception

Deprecated. Use handleRequest( HttpServletRequest request, HttpServletResponse response, Context ctx )

Implement this method to add your application data to the context, calling the getTemplate() method to produce your return value.

In the event of a problem, you may simple return null or throw a more meaningful exception.

Parameters:

ctx - The context to add your data to.

Returns:

The template to merge with your context.

Throws:

Exception

error

protected void error(HttpServletRequest request,
                     HttpServletResponse response,
                     Exception cause)
              throws ServletException,
                     IOException

Deprecated.

Invoked when there is an error thrown in any part of doRequest() processing.

Default will send a simple HTML response indicating there was a problem.

Parameters:

request - original HttpServletRequest from servlet container.

response - HttpServletResponse object from servlet container.

cause - Exception that was thrown by some other part of process.

Throws:

ServletException

IOException