Jetty Utilities 6.1.26 · org.mortbay.servlet.ConcatServlet

Concatenation Servlet This servlet may be used to concatenate multiple resources into a single response. It is intended to be used to load multiple javascript or css files, but may be used for any content of the same mime type that can be meaningfully concatenated.

The servlet uses RequestDispatcher#include(javax.servlet.ServletRequest, javax.servlet.ServletResponse) to combine the requested content, so dynamically generated content may be combined (Eg engine.js for DWR).

The servlet uses parameter names of the query string as resource names relative to the context root. So these script tags:

 <script type="text/javascript" src="../js/behaviour.js"></script>
 <script type="text/javascript" src="../js/ajax.js&/chat/chat.js"></script>
 <script type="text/javascript" src="../chat/chat.js"></script>

can be replaced with the single tag (with the ConcatServlet mapped to /concat):

 <script type="text/javascript" src="../concat?/js/behaviour.js&/js/ajax.js&/chat/chat.js"></script>

The ServletContext#getMimeType(String) method is used to determine the mime type of each resource. If the types of all resources do not match, then a 415 UNSUPPORTED_MEDIA_TYPE error is returned.

If the init parameter "development" is set to "true" then the servlet will run in development mode and the content will be concatenated on every request. Otherwise the init time of the servlet is used as the lastModifiedTime of the combined content and If-Modified-Since requests are handled with 206 NOT Modified responses if appropriate. This means that when not in development mode, the servlet must be restarted before changed content will be served.

Modifier and Type	Field and Description
pack-priv ServletContext	_context
pack-priv boolean	_development
pack-priv long	_lastModified

Constructor Summary

Access	Constructor and Description
public	ConcatServlet()

Method Summary

Modifier and Type	Method and Description
protected void	doGet(HttpServletRequest an `HttpServletRequest` object that contains the request the client has made of the servlet req, HttpServletResponse an `HttpServletResponse` object that contains the response the servlet sends to the client resp) Overrides javax.servlet.http.HttpServlet.doGet. Called by the server (via the `service` method) to allow a servlet to handle a GET request.
protected long	getLastModified(HttpServletRequest the `HttpServletRequest` object that is sent to the servlet req) Overrides javax.servlet.http.HttpServlet.getLastModified. Returns the time the `HttpServletRequest` object was last modified, in milliseconds since midnight January 1, 1970 GMT.
public void	init() Overrides javax.servlet.GenericServlet.init. A convenience method which can be overridden so that there's no need to call `super.init(config)`.

Inherited from javax.servlet.http.HttpServlet:: doDelete doHead doOptions doPost doPut doTrace service service

Field Detail

_context	back to summary
pack-priv ServletContext _context

_development	back to summary
pack-priv boolean _development

_lastModified	back to summary
pack-priv long _lastModified

Constructor Detail

ConcatServlet	back to summary
public ConcatServlet()

Method Detail

doGet back to summary

doGet	back to summary
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException Overrides javax.servlet.http.HttpServlet.doGet. Doc from javax.servlet.http.HttpServlet.doGet. Called by the server (via the `service` method) to allow a servlet to handle a GET request. Overriding this method to support a GET request also automatically supports an HTTP HEAD request. A HEAD request is a GET request that returns no body in the response, only the request header fields. When overriding this method, read the request data, write the response headers, get the response's writer or output stream object, and finally, write the response data. It's best to include content type and encoding. When using a `PrintWriter` object to return the response, set the content type before accessing the `PrintWriter` object. The servlet container must write the headers before committing the response, because in HTTP the headers must be sent before the response body. Where possible, set the Content-Length header (with the `javax.servlet.ServletResponse#setContentLength` method), to allow the servlet container to use a persistent connection to return its response to the client, improving performance. The content length is automatically set if the entire response fits inside the response buffer. When using HTTP 1.1 chunked encoding (which means that the response has a Transfer-Encoding header), do not set the Content-Length header. The GET method should be safe, that is, without any side effects for which users are held responsible. For example, most form queries have no side effects. If a client request is intended to change stored data, the request should use some other HTTP method. The GET method should also be idempotent, meaning that it can be safely repeated. Sometimes making a method safe also makes it idempotent. For example, repeating queries is both safe and idempotent, but buying a product online or modifying data is neither safe nor idempotent. If the request is incorrectly formatted, `doGet` returns an HTTP "Bad Request" message. Parameters req:HttpServletRequest an `HttpServletRequest` object that contains the request the client has made of the servlet resp:HttpServletResponse an `HttpServletResponse` object that contains the response the servlet sends to the client Exceptions ServletException: if the request for the GET could not be handled IOException: if an input or output error is detected when the servlet handles the GET request

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException

Overrides javax.servlet.http.HttpServlet.doGet.

Doc from javax.servlet.http.HttpServlet.doGet.

Called by the server (via the service method) to allow a servlet to handle a GET request.

Overriding this method to support a GET request also automatically supports an HTTP HEAD request. A HEAD request is a GET request that returns no body in the response, only the request header fields.

When overriding this method, read the request data, write the response headers, get the response's writer or output stream object, and finally, write the response data. It's best to include content type and encoding. When using a PrintWriter object to return the response, set the content type before accessing the PrintWriter object.

The servlet container must write the headers before committing the response, because in HTTP the headers must be sent before the response body.

Where possible, set the Content-Length header (with the javax.servlet.ServletResponse#setContentLength method), to allow the servlet container to use a persistent connection to return its response to the client, improving performance. The content length is automatically set if the entire response fits inside the response buffer.

When using HTTP 1.1 chunked encoding (which means that the response has a Transfer-Encoding header), do not set the Content-Length header.

The GET method should be safe, that is, without any side effects for which users are held responsible. For example, most form queries have no side effects. If a client request is intended to change stored data, the request should use some other HTTP method.

The GET method should also be idempotent, meaning that it can be safely repeated. Sometimes making a method safe also makes it idempotent. For example, repeating queries is both safe and idempotent, but buying a product online or modifying data is neither safe nor idempotent.

If the request is incorrectly formatted, doGet returns an HTTP "Bad Request" message.

Parameters

req:HttpServletRequest: an HttpServletRequest object that contains the request the client has made of the servlet
resp:HttpServletResponse: an HttpServletResponse object that contains the response the servlet sends to the client

Exceptions

ServletException:: if the request for the GET could not be handled
IOException:: if an input or output error is detected when the servlet handles the GET request

getLastModified back to summary

getLastModified	back to summary
protected long getLastModified(HttpServletRequest req) Overrides javax.servlet.http.HttpServlet.getLastModified. Doc from javax.servlet.http.HttpServlet.getLastModified. Returns the time the `HttpServletRequest` object was last modified, in milliseconds since midnight January 1, 1970 GMT. If the time is unknown, this method returns a negative number (the default). Servlets that support HTTP GET requests and can quickly determine their last modification time should override this method. This makes browser and proxy caches work more effectively, reducing the load on server and network resources. Parameters req:HttpServletRequest the `HttpServletRequest` object that is sent to the servlet Returns:long a `long` integer specifying the time the `HttpServletRequest` object was last modified, in milliseconds since midnight, January 1, 1970 GMT, or -1 if the time is not known

protected long getLastModified(HttpServletRequest req)

Overrides javax.servlet.http.HttpServlet.getLastModified.

Doc from javax.servlet.http.HttpServlet.getLastModified.

Returns the time the HttpServletRequest object was last modified, in milliseconds since midnight January 1, 1970 GMT. If the time is unknown, this method returns a negative number (the default).

Servlets that support HTTP GET requests and can quickly determine their last modification time should override this method. This makes browser and proxy caches work more effectively, reducing the load on server and network resources.

Parameters

req:HttpServletRequest: the HttpServletRequest object that is sent to the servlet

Returns:long

a long integer specifying the time the HttpServletRequest object was last modified, in milliseconds since midnight, January 1, 1970 GMT, or -1 if the time is not known

init back to summary

init	back to summary
public void init() throws ServletException Overrides javax.servlet.GenericServlet.init. Doc from javax.servlet.GenericServlet.init. A convenience method which can be overridden so that there's no need to call `super.init(config)`. Instead of overriding `init(ServletConfig)`, simply override this method and it will be called by `GenericServlet.init(ServletConfig config)`. The `ServletConfig` object can still be retrieved via `getServletConfig`. Exceptions ServletException: if an exception occurs that interrupts the servlet's normal operation

public void init() throws ServletException

Overrides javax.servlet.GenericServlet.init.

Doc from javax.servlet.GenericServlet.init.

A convenience method which can be overridden so that there's no need to call super.init(config).

Instead of overriding init(ServletConfig), simply override this method and it will be called by GenericServlet.init(ServletConfig config). The ServletConfig object can still be retrieved via getServletConfig.