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de.laures.cewolf
Class CewolfRenderer  

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          de.laures.cewolf.CewolfRenderer

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig, WebConstants

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public class CewolfRenderer

extends javax.servlet.http.HttpServlet

implements WebConstants

The rendering servlet of Cewolf. It is resposible for writing an entire chart img into the response stream of the client. Everything needed for this is prepared already by the ChartImgTag resp. LegendTag. The ID of a chart image is passed to this servlet as a request parameter. After that the image object is retrieved from the server side session based image cache. This servlet must be configured in web.xml of the web application in order to use Cewolf services. The servlet's URL relative to the web apps root is used as the renderer attribute of the ChartImgTag resp. LegendTag in the JSP page.

Since:

0.1

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Field Summary
private  Configuration	config
private  boolean	debugged
static java.lang.String	INIT_CONFIG
private  int	requestCount
private static java.lang.String	STATE

 

Fields inherited from class javax.servlet.http.HttpServlet

 

Fields inherited from interface de.laures.cewolf.WebConstants

AMPERSAND, HEIGHT_PARAM, IMG_PARAM, MIME_PNG, MIME_SVG, SESSIONID_KEY, WIDTH_PARAM

 

Constructor Summary

CewolfRenderer()

 

Method Summary
private  void	addHeaders(javax.servlet.http.HttpServletResponse response)           Method addHeaders.
protected  void	doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)           Called by the server (via the service method) to allow a servlet to handle a GET request.
void	init(javax.servlet.ServletConfig servletCfg)           Called by the servlet container to indicate to a servlet that the servlet is being placed into service.
private  void	logAndRenderException(java.lang.Throwable ex, javax.servlet.http.HttpServletResponse response, int width, int height)
private  void	logRequest(javax.servlet.http.HttpServletRequest request)
void	printParameters(javax.servlet.http.HttpServletRequest request)           Processes HTTP GET request.
private  void	renderImageExpiry(javax.servlet.http.HttpServletResponse response, int width, int height)           Method renderImageExpiry.
private  void	requestState(javax.servlet.http.HttpServletResponse response)           Method requestState.

 

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPost, 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

INIT_CONFIG

public static final java.lang.String INIT_CONFIG

See Also:

Constant Field Values

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STATE

private static final java.lang.String STATE

See Also:

Constant Field Values

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debugged

private boolean debugged

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requestCount

private int requestCount

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config

private Configuration config

Constructor Detail

CewolfRenderer

public CewolfRenderer()

Method Detail

init

public void init(javax.servlet.ServletConfig servletCfg)
          throws javax.servlet.ServletException

Description copied from class: javax.servlet.GenericServlet

Called by the servlet container to indicate to a servlet that the servlet is being placed into service. See Servlet.init(javax.servlet.ServletConfig)>Servlet.init(javax.servlet.ServletConfig) 55 .

This implementation stores the javax.servlet.ServletConfig object it receives from the servlet container for later use. When overriding this form of the method, call super.init(config).

Specified by:

init in interface javax.servlet.Servlet

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printParameters

public void printParameters(javax.servlet.http.HttpServletRequest request)

Processes HTTP GET request. Renders the chart or the lengend into the client's response stream.

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doGet

protected void doGet(javax.servlet.http.HttpServletRequest request,
                     javax.servlet.http.HttpServletResponse response)
              throws javax.servlet.ServletException,
                     java.io.IOException

Description copied from class: javax.servlet.http.HttpServlet

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 ServletResponse.setContentLength(int)>ServletResponse.setContentLength(int) 55 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.

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addHeaders

private void addHeaders(javax.servlet.http.HttpServletResponse response)

Method addHeaders.

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requestState

private void requestState(javax.servlet.http.HttpServletResponse response)
                   throws java.io.IOException

Method requestState.

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logAndRenderException

private void logAndRenderException(java.lang.Throwable ex,
                                   javax.servlet.http.HttpServletResponse response,
                                   int width,
                                   int height)
                            throws java.io.IOException

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renderImageExpiry

private void renderImageExpiry(javax.servlet.http.HttpServletResponse response,
                               int width,
                               int height)
                        throws java.io.IOException

Method renderImageExpiry.

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logRequest

private void logRequest(javax.servlet.http.HttpServletRequest request)
                 throws java.io.IOException

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> de >> laures >> [ cewolf overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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