com.vmax.servlet.core
Class CachedGraphicsServlet

java.lang.Object
  |
  +--javax.servlet.GenericServlet
        |
        +--javax.servlet.http.HttpServlet
              |
              +--com.vmax.servlet.core.CachedServlet
                    |
                    +--com.vmax.servlet.core.CachedGraphicsServlet

All Implemented Interfaces:

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

Direct Known Subclasses:

FramerServlet, T2IServlet

public abstract class CachedGraphicsServlet

extends com.vmax.servlet.core.CachedServlet

This class provides basic functinality for Graphics servlets suite. To implement your own graphics servlet you only need to override 3 abstract methods

Author:

virtual_max (aka virtual_max@geocities.com)

See Also:

Serialized Form

Field Summary

static int	ALIGN_BOTTOM bottom alignment
static int	ALIGN_CENTER center horizontal alignment
static int	ALIGN_LEFT Left alignment
static int	ALIGN_MIDDLE Middle verrtial allignment
static int	ALIGN_RIGHT right alinment
static int	ALIGN_TOP TOP alignment
static long	DAY
static long	HOUR
static long	MONTH
static java.lang.String	TTL
static long	WEEK
static long	YEAR

Constructor Summary

CachedGraphicsServlet()

Method Summary

protected java.lang.String	countHash(BasicHttpRequest req, java.lang.String[] parameterNames)
void	destroy()
void	drawLines(java.awt.Graphics2D graphics, java.util.List lines, java.awt.Rectangle text_rect, java.awt.FontMetrics fm, int align) Method to draw text lines
abstract java.lang.String[]	getActualParameterNames() This method supposed to return array of parameters names which are actual parameters for your servlet, this is necessary because request may contain other parameters which are not in use.
int	getAlignParameter(BasicHttpRequest req, java.lang.String name, int deft) Usefull function to obtain alignment parameters.
java.lang.String	getBasePath()
java.awt.Color	getColorParam(BasicHttpRequest req, java.lang.String name, int deft) Usefull function to obtain parameter value from request as hex value of color in aarrggbb format and construct Color object.
abstract java.lang.String	getContentType(javax.servlet.http.HttpServletRequest req) This method is used to get content type for setting response content type.
protected long	getExpiration(javax.servlet.http.HttpServletRequest req)
java.io.File	getFontsDir() method to get fonts directory defined with servlet init parameter fonts_dir
int	getHexParam(BasicHttpRequest req, java.lang.String name, int deft) Usefull function to obtain String parameter value from request interpreting it as hexadecimal string or use default.
java.awt.image.BufferedImage	getImageParam(BasicHttpRequest req, java.lang.String name) Usful method to get parameter value as image name and looad image from backgrounds directory.
java.awt.FontMetrics	getMetrics(java.awt.Font font) Function to obtain font metrics for futher dimensions calculations
int	getParam(BasicHttpRequest req, java.lang.String name, int deft) Usefull function to obtain int parameter value interpreting it as decimal integer string from request or use default.
java.lang.String	getParam(BasicHttpRequest req, java.lang.String name, java.lang.String deft) Usefull function to obtain String parameter value from request or use default.
java.awt.Dimension	getRequiredRect(java.util.List lines, java.awt.FontMetrics fm, int minWidth, int minHeight) Method to obtain dimensions required to fit List of lines
static java.io.File	getWorkingDir(javax.servlet.ServletContext context, java.lang.String paramName, java.lang.String deft, boolean create)
java.io.File	getWorkingDir(java.lang.String paramName, java.lang.String deft, boolean create)
void	init(javax.servlet.ServletConfig servletConfig)
java.awt.Font	loadFontFromPath(java.lang.String fontpath, int fontSize) Function to get Font.
java.lang.String	seekParam(BasicHttpRequest req, java.lang.String name)
abstract void	serve(BasicHttpRequest req, java.io.ByteArrayOutputStream baos) Basic painting method to implement pinting logic.
protected void	service(BasicHttpRequest req, javax.servlet.http.HttpServletResponse res, long expiration)
void	service(javax.servlet.ServletRequest req, javax.servlet.ServletResponse res)
void	setRenderingHints(java.awt.Graphics2D g) Set optimal rendering parameters for generating graphics
protected void	setResponseHeaders(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res) If you need to add specific headers to response, than override this method
java.util.ArrayList	splitText(java.lang.String text, java.awt.FontMetrics fm, int w) Function to split text in multiline in desired width using given fontMetrics.
static void	tileBackground(java.awt.image.BufferedImage im, java.awt.Graphics2D graphics, java.awt.image.BufferedImage bgim, int align) Method to tile background image over given graphics object

Methods inherited from class javax.servlet.http.HttpServlet

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

Methods inherited from class javax.servlet.GenericServlet

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

ALIGN_TOP

public static final int ALIGN_TOP

TOP alignment

See Also:

Constant Field Values

ALIGN_MIDDLE

public static final int ALIGN_MIDDLE

Middle verrtial allignment

See Also:

Constant Field Values

ALIGN_BOTTOM

public static final int ALIGN_BOTTOM

bottom alignment

See Also:

Constant Field Values

ALIGN_LEFT

public static final int ALIGN_LEFT

Left alignment

See Also:

Constant Field Values

ALIGN_CENTER

public static final int ALIGN_CENTER

center horizontal alignment

See Also:

Constant Field Values

ALIGN_RIGHT

public static final int ALIGN_RIGHT

right alinment

See Also:

Constant Field Values

TTL

public static final java.lang.String TTL

See Also:

Constant Field Values

YEAR

public static final long YEAR

See Also:

Constant Field Values

MONTH

public static final long MONTH

See Also:

Constant Field Values

WEEK

public static final long WEEK

See Also:

Constant Field Values

DAY

public static final long DAY

See Also:

Constant Field Values

HOUR

public static final long HOUR

See Also:

Constant Field Values

Constructor Detail

CachedGraphicsServlet

public CachedGraphicsServlet()

Method Detail

getActualParameterNames

public abstract java.lang.String[] getActualParameterNames()

This method supposed to return array of parameters names which are actual parameters for your servlet, this is necessary because request may contain other parameters which are not in use. This parameters values will be used for generating cache entry key.

Overrides:

getActualParameterNames in class com.vmax.servlet.core.CachedServlet

Returns:

array of strings containing parameter names.

getContentType

public abstract java.lang.String getContentType(javax.servlet.http.HttpServletRequest req)

This method is used to get content type for setting response content type.

Overrides:

getContentType in class com.vmax.servlet.core.CachedServlet

Parameters:

req - - original http request

Returns:

content type to set in response

serve

public abstract void serve(BasicHttpRequest req,
                           java.io.ByteArrayOutputStream baos)
                    throws java.lang.Exception

Basic painting method to implement pinting logic.

Overrides:

serve in class com.vmax.servlet.core.CachedServlet

Parameters:

req - - request wrapper

baos - - output stream to write image data

Throws:

java.lang.Exception

init

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

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class com.vmax.servlet.core.CachedServlet

javax.servlet.ServletException

setRenderingHints

public void setRenderingHints(java.awt.Graphics2D g)

Set optimal rendering parameters for generating graphics

Parameters:

g -

loadFontFromPath

public java.awt.Font loadFontFromPath(java.lang.String fontpath,
                                      int fontSize)
                               throws java.io.IOException,
                                      java.awt.FontFormatException

Function to get Font. Path may be absolute or relative to project base directory

Parameters:

fontpath - - name of font file or path to font file, relative to fonts_dir

fontSize - - font sixe in pixels

Returns:

- Font object.

Throws:

java.io.IOException

java.awt.FontFormatException

getMetrics

public java.awt.FontMetrics getMetrics(java.awt.Font font)

Function to obtain font metrics for futher dimensions calculations

getColorParam

public java.awt.Color getColorParam(BasicHttpRequest req,
                                    java.lang.String name,
                                    int deft)

Usefull function to obtain parameter value from request as hex value of color in aarrggbb format and construct Color object. This function seek for parameter in the following order:
first - parameter passed in traditional way (GET or POST)
second - parameter passed via path info as <servletName>/param1/value1/param2/value2
third - check for properties file optionaly specified with wtk_defaults parameter for default of this value forth - attempt to get default value from serlet init parameters
last - use default value passed to function

Parameters:

req - - request

name - - parameter name

deft - - default value

Returns:

- Color object

getParam

public java.lang.String getParam(BasicHttpRequest req,
                                 java.lang.String name,
                                 java.lang.String deft)

Usefull function to obtain String parameter value from request or use default. This function seek for parameter in the following order:
first - parameter passed in traditional way (GET or POST)
second - parameter passed via path info as <servletName>/param1/value1/param2/value2
third - check for properties file optionaly specified with wtk_defaults parameter for default of this value forth - attempt to get default value from serlet init parameters
last - use default value passed to function

Parameters:

req - - request

name - - parameter name

deft - - default value

Returns:

- parameter value

getParam

public int getParam(BasicHttpRequest req,
                    java.lang.String name,
                    int deft)

Usefull function to obtain int parameter value interpreting it as decimal integer string from request or use default. This function seek for parameter in the following order:
first - parameter passed in traditional way (GET or POST)
second - parameter passed via path info as <servletName>/param1/value1/param2/value2
third - check for properties file optionaly specified with wtk_defaults parameter for default of this value forth - attempt to get default value from serlet init parameters
last - use default value passed to function

Parameters:

req - - request

name - - parameter name

deft - - default value

Returns:

- integer parameter value

getHexParam

public int getHexParam(BasicHttpRequest req,
                       java.lang.String name,
                       int deft)

Usefull function to obtain String parameter value from request interpreting it as hexadecimal string or use default. This function seek for parameter in the following order:
first - parameter passed in traditional way (GET or POST)
second - parameter passed via path info as <servletName>/param1/value1/param2/value2
third - check for properties file optionaly specified with wtk_defaults parameter for default of this value forth - attempt to get default value from serlet init parameters
last - use default value passed to function

Parameters:

req - - request

name - - parameter name

deft - - default value

Returns:

- hex parameter value

getAlignParameter

public int getAlignParameter(BasicHttpRequest req,
                             java.lang.String name,
                             int deft)

Usefull function to obtain alignment parameters. It check string parameter value for keywords
top,middle,bottom,left,right and center. This function seek for parameter in the following order:
first - parameter passed in traditional way (GET or POST)
second - parameter passed via path info as <servletName>/param1/value1/param2/value2
third - check for properties file optionaly specified with wtk_defaults parameter for default of this value forth - attempt to get default value from serlet init parameters
last - use default value passed to function

Parameters:

req - - request

name - - parameter name

deft - - default value

Returns:

- alligment integer value, combination (by OR) if alingment constants defined in this class

splitText

public java.util.ArrayList splitText(java.lang.String text,
                                     java.awt.FontMetrics fm,
                                     int w)

Function to split text in multiline in desired width using given fontMetrics. This function also trims spaces and force split when \n character is found. When width == 0 then split only on new line chars.

Parameters:

text -

fm -

w -

Returns:

- arrayList of text rows

getRequiredRect

public java.awt.Dimension getRequiredRect(java.util.List lines,
                                          java.awt.FontMetrics fm,
                                          int minWidth,
                                          int minHeight)

Method to obtain dimensions required to fit List of lines

Parameters:

lines - - ordered List of text lines

fm - - font metrics to use for text dimensions calculations

minWidth - - minimum Width to return

minHeight - - minimumHeight to return

Returns:

Dimension enough to fit text rows but not less then spicified minimums.

drawLines

public void drawLines(java.awt.Graphics2D graphics,
                      java.util.List lines,
                      java.awt.Rectangle text_rect,
                      java.awt.FontMetrics fm,
                      int align)

Method to draw text lines

Parameters:

graphics - - graphics object to draw on.

lines - - ordered List of lines

text_rect - - rectangle to define offsets and dimensions of text alignment bounds.

fm - - font metrics object for size calculations

align - - alignment parameter

getImageParam

public java.awt.image.BufferedImage getImageParam(BasicHttpRequest req,
                                                  java.lang.String name)

Usful method to get parameter value as image name and looad image from backgrounds directory.

Parameters:

req - - http request

name - - image file name

Returns:

- Buffered image or null

tileBackground

public static void tileBackground(java.awt.image.BufferedImage im,
                                  java.awt.Graphics2D graphics,
                                  java.awt.image.BufferedImage bgim,
                                  int align)

Method to tile background image over given graphics object

Parameters:

im - - image to paint over, passed only to obtain it's dimensions

graphics - - graphics object to draw on

bgim - - background image to tile

align - - background alignment.

getFontsDir

public java.io.File getFontsDir()

method to get fonts directory defined with servlet init parameter fonts_dir

Returns:

directory

setResponseHeaders

protected void setResponseHeaders(javax.servlet.http.HttpServletRequest req,
                                  javax.servlet.http.HttpServletResponse res)

If you need to add specific headers to response, than override this method

Parameters:

req -

res -

countHash

protected java.lang.String countHash(BasicHttpRequest req,
                                     java.lang.String[] parameterNames)
                              throws java.io.UnsupportedEncodingException

java.io.UnsupportedEncodingException

getWorkingDir

public java.io.File getWorkingDir(java.lang.String paramName,
                                  java.lang.String deft,
                                  boolean create)

getWorkingDir

public static java.io.File getWorkingDir(javax.servlet.ServletContext context,
                                         java.lang.String paramName,
                                         java.lang.String deft,
                                         boolean create)

service

protected void service(BasicHttpRequest req,
                       javax.servlet.http.HttpServletResponse res,
                       long expiration)
                throws javax.servlet.ServletException,
                       java.io.IOException

javax.servlet.ServletException

java.io.IOException

service

public void service(javax.servlet.ServletRequest req,
                    javax.servlet.ServletResponse res)
             throws javax.servlet.ServletException,
                    java.io.IOException

Specified by:

service in interface javax.servlet.Servlet

Overrides:

service in class javax.servlet.http.HttpServlet

javax.servlet.ServletException

java.io.IOException

getExpiration

protected long getExpiration(javax.servlet.http.HttpServletRequest req)

getBasePath

public java.lang.String getBasePath()

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Servlet

Overrides:

destroy in class javax.servlet.GenericServlet

seekParam

public java.lang.String seekParam(BasicHttpRequest req,
                                  java.lang.String name)