javawebparts.servlet
Class TextRendererServlet

java.lang.Object
  |
  +--javax.servlet.GenericServlet
        |
        +--javax.servlet.http.HttpServlet
              |
              +--javawebparts.servlet.TextRendererServlet

All Implemented Interfaces:

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

public class TextRendererServlet

extends javax.servlet.http.HttpServlet

This servlet serves a dynamically-rendered image of a string of text with the specified font characteristics.

Example configuration in web.xml:

<servlet>
<servlet-name>TextRendererServlet</servlet-name>
<servlet-class>javawebparts.servlet. TextRendererServlet</servlet-class>
<init-param>
<param-name>fontName</param-name>
<param-value>arial</param-value>
</init-param>
<init-param>
<param-name>fontPoint</param-name>
<param-value>24</param-value>
</init-param>
<init-param>
<param-name>color</param-name>
<param-value>255,0,0 </param-value>
</init-param>
<init-param>
<param-name>backColor</param-name>
<param-value>255,255,0 </param-value>
</init-param>
<init-param>
<param-name>stylePlain</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>styleBold</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>styleItalic</param-name>
<param-value>true</param-value>
</init-param>
</servlet>

<servlet-mapping>
<servlet-name>TextRendererServlet</servlet-name>
<url-pattern>/textRenderer</url-pattern>
</servlet-mapping>

Init parameters explained:

• fontName - This can be any font installed on the server that the servlet runs on, and it is what font the text will be rendered with. For more information, see the Font class in the standard Java SDK, as this value is used in the call to the constructor of that class. Required: No. Default: Arial.
• fontPoint - This is what point size the text will be rendered in. For more information, see the Font class in the standard Java SDK, as this value is used in the call to the constructor of that class. Required: No. Default: 12.
• color - This is a comma-separated list of red, green, blue color component values (0-255 each) that will be mixed together and used as the color of the text. For example, 255,0,0 is pure red, 255,255,0 is yellow, 255,0,255 is purple, etc. Required: No. Default: 0,0,0 (black).
• backColor - Same as the color, except this is the background color of the rendered image. Required: No. Default: 255,255,255 (white).
• stylePlain - One of the three font style paramters. If set to true, the text will be rendered in it's plain style. Note that setting plain=true overrides any setting of styleBold and styleItalics. For more information, see the Font class in the standard Java SDK, as this value is used in the call to the constructor of that class. Required: No. Default: true.
• styleBold - One of the three font style parameters. If set to true, the text will be rendered in bold style. For more information, see the Font class in the standard Java SDK, as this value is used in the call to the constructor of that class. Required: No. Default: false.
• styleItalic - One of the three font style parameters. If set to true, the text will be rendered in italic style. For more information, see the Font class in the standard Java SDK, as this value is used in the call to the constructor of that class. Required: No. Default: false.

All of the above parameters can be passed in as request parameters to the servlet as well, and the request parameters will override the servlet init paramter values. Also note that all of the above init parameters are optional. However, the font, fontPoint, color and backColor parameters ARE IN FACT REQUIRED FOR THE SERVLET TO FUNCTION! They MUST be supplied either as init values or as request parameters. You can mix and match as appropriate, i.e., if you want to only render in Arial, then set the fontName init parameter and do not pass a fontName request parameter in. IF a particular parameter is found as neither an init parameter or a request parameter, the above specified default values are used. If the text parameter is not found in request, a blank image will be returned, but no error will occur.

The most common usage of this servlet is usually to use it as the src of an <img> tag with some or all of the required parameters attached as a query string. For example:

<img src="/TextRenderer?fontPoint=32&text=testing123">

The method that actually renders the text, appropriately named renderText(), is public and stand-alone and available to any outside code, so if you want to use the functionality of the servlet from your own code without actually using it as a servlet, simply instantiate it as any other class and call this method. It accepts a Map which contains the following elements:

• Integer colR
• Integer colG
• Integer colB
• Integer backR
• Integer backG
• Integer backB
• Integer fontPoint
• String fontName
• String stylePlain
• String styleBold
• String styleItalic
• String text

They should all be familiar. colR, colG and colB are the RGB components of the foreground color, and backR, backG and backB are the RGB components of the background color. It returns an OutputStream (ByteArrayOutputStream specifically) whichis the rendered image. You can do whatever you want to with it at that point.

Author:

Frank W. Zammetti.

See Also:

Serialized Form

Field Summary

private java.lang.Integer	initBackB backB.
private java.lang.Integer	initBackG backG.
private java.lang.Integer	initBackR backR.
private java.lang.Integer	initColB colB.
private java.lang.Integer	initColG colG.
private java.lang.Integer	initColR colR.
private java.lang.String	initFontName font.
private java.lang.Integer	initFontPoint fontPoint.
private java.lang.String	initStyleBold styleBold.
private java.lang.String	initStyleItalic styleItalic.
private java.lang.String	initStylePlain stylePlain.
private static org.apache.commons.logging.Log	log Log instance.

Fields inherited from class javax.servlet.http.HttpServlet

Fields inherited from class javax.servlet.GenericServlet

Constructor Summary

TextRendererServlet()

Method Summary

void	doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) doGet.
void	doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) doPost.
void	init(javax.servlet.ServletConfig config) init.
static java.io.OutputStream	renderText(java.util.Map m) This method is the method which actually renders a given text string using the given font characteristics and returns the image as an OutputStream (ByteArrayOutputStream specifically).

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

log

private static org.apache.commons.logging.Log log

Log instance.

initFontName

private java.lang.String initFontName

font.

initFontPoint

private java.lang.Integer initFontPoint

fontPoint.

initStylePlain

private java.lang.String initStylePlain

stylePlain.

initStyleBold

private java.lang.String initStyleBold

styleBold.

initStyleItalic

private java.lang.String initStyleItalic

styleItalic.

initColR

private java.lang.Integer initColR

colR.

initColG

private java.lang.Integer initColG

colG.

initColB

private java.lang.Integer initColB

colB.

initBackR

private java.lang.Integer initBackR

backR.

initBackG

private java.lang.Integer initBackG

backG.

initBackB

private java.lang.Integer initBackB

backB.

Constructor Detail

TextRendererServlet

public TextRendererServlet()

Method Detail

init

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

init.

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class javax.servlet.GenericServlet

Parameters:

config - ServletConfig.

Throws:

javax.servlet.ServletException - ServletException.

doGet

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

doGet. Calls doPost() to do real work.

Overrides:

doGet in class javax.servlet.http.HttpServlet

Parameters:

request - HTTPServletRequest.

response - HTTPServletResponse.

Throws:

javax.servlet.ServletException - ServletException.

java.io.IOException - IOExcpetion.

doPost

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

doPost.

Overrides:

doPost in class javax.servlet.http.HttpServlet

Parameters:

request - HTTPServletRequest

response - HTTPServletResponse

Throws:

javax.servlet.ServletException - ServletException

java.io.IOException - IOExcpetion

renderText

public static java.io.OutputStream renderText(java.util.Map m)
                                       throws java.io.IOException

This method is the method which actually renders a given text string using the given font characteristics and returns the image as an OutputStream (ByteArrayOutputStream specifically).

Parameters:

m - A Map containing all the required elements. See the javadocs for this class for details.

Returns:

An OutputStream (ByteArrayOutputStream specifically) that is the final rendered image.

Throws:

java.io.IOException - IOException