lazyj
Class ExtendedServlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          lazyj.ExtendedServlet

All Implemented Interfaces:

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

public abstract class ExtendedServlet
extends javax.servlet.http.HttpServlet
implements javax.servlet.SingleThreadModel

Probably the most important class in the world :)

This class is a wrapper over the original HttpServlet, adding caching and run time limit for the servlets. There are also other useful functions, like initMultipartRequest(String, int) for uploading files, getX (s/i/f/d) for parsing the parameters and getting the correct value, getCookie(String), setCookie(String, String), log(int, String)

Since:

2006-10-02

Author:

costing

See Also:

RequestWrapper, Serialized Form

Field Summary

protected boolean	bGet Servlets can treat GET and POST differently based on the method they override or by looking at this variable
protected boolean	bRedirect Remember whether or not there was a redirect executed by the servlet
DBSession	dbs Current session
static long	lServerStarted This is when the server was started
protected com.oreilly.servlet.MultipartRequest	mpRequest Object used for file uploading.
protected java.io.OutputStream	osOut OutputStream to the client
protected java.io.PrintWriter	pwOut PrintWriter to the client.
protected javax.servlet.http.HttpServletRequest	request The original request object
protected javax.servlet.http.HttpServletResponse	response The original response object
protected java.lang.String	sPage Current servlet that is executed
protected java.lang.String	sZone The zone of the currently executed servlet

Constructor Summary

ExtendedServlet()

Method Summary

void	doGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp) Original request from servlet engine comes through here.
protected void	doInit() This is a hook provided for the servlets as a generic way to initialize their local variables, do authentication and so on.
void	doPost(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp) Original request from servlet engine comes through here.
static java.lang.String	esc(java.lang.String s) Produce safe SQL strings.
static java.lang.String	escHtml(java.lang.String s) Produce save HTML strings.
abstract void	execGet() A servlet must implement at least this method.
void	execPost() By default POST request are executed with the same execGet() function.
protected int	getApp() Get the application number.
static long	getCacheAccesses() Statistics: get the total number of accesses to pages that could be cached
static long	getCacheHits() Statistics: get the number of cache hits
protected java.lang.String	getCacheKeyModifier() Override this method to return any value that would alter the cache.
protected long	getCacheTimeout() Method to specify the maximum life time of the cached contents.
java.lang.String	getCookie(java.lang.String sName) Get the value of a specific cookie
java.lang.String	getCurrentPage() Compose the full URL to the current page.
double	getd(java.lang.String sParam) Get the value of a parameter as a double value.
double	getd(java.lang.String sParam, double defaultVal) Get the value of a parameter as a double value.
protected java.lang.String	getDomain() Method to specify the domain for which the cookies will be set by default (session cookie included).
float	getf(java.lang.String sParam) Get the value of a parameter as a float value.
float	getf(java.lang.String sParam, float defaultVal) Get the value of a parameter as a float value.
static long	getFrameworkRequests() Framework statistics: get the total number of requests serviced by the framework.
java.lang.String	getHostAddr() Get the client host address (IP).
java.lang.String	getHostName() Get the nice host name for the client that made the current request.
int	geti(java.lang.String sParam) Get the value of a parameter as an integer value.
int	geti(java.lang.String sParam, int defaultVal) Get the value of a parameter as an integer value.
long	getl(java.lang.String sParam) Get the value of a parameter as a long value.
long	getl(java.lang.String sParam, long defaultVal) Get the value of a parameter as a long value.
protected int	getMaxRunTime() Method to specify the maximum run time for a page.
protected int	getOnlineUsers() Get the number of online users for the current application.
java.lang.String	gets(java.lang.String sParam) Get the value of a parameter as a string.
java.lang.String	gets(java.lang.String sParam, java.lang.String sDefault) Get the value of a parameter as a string.
static java.lang.String	getServerUptime() Statistics: get the server uptime
java.lang.String[]	getValues(java.lang.String sParam) Get all the values of a parameter.
protected boolean	initMultipartRequest(java.lang.String sTempDir, int iFileSizeLimit) This method should be called when the servlet expects a file upload from the client.
boolean	isLoggable(int iLevel) Find out whether or not the current page is able to log this level of debug.
boolean	isSessionIPProtected() Flag to set whether or not the session is valid only when used from the first IP that generated the session.
void	log(int level, java.lang.String sMessage) Log messages with a given level of the problem.
void	log(int level, java.lang.String sMessage, java.lang.Object o) Special logging for exceptions.
void	log(java.lang.String sMessage) Override the method provided by the Java Servlet Api to log messages as DEBUG
protected boolean	redirect(java.lang.String sURL) Wrapper method for the actual redirect, that keeps track if there was such an opperation.
void	setContentType(java.lang.String sContentType) If you set the content type to something else than "text/html; charset=UTF-8" and you use the caching mechanism you should use this method instead of directly calling response.setContentType
boolean	setCookie(java.lang.String sName, java.lang.String sValue) Send a session cookie to the browser.
boolean	setCookie(java.lang.String sName, java.lang.String sValue, int iAge) Send a cookie to the browser.
boolean	setCookie(java.lang.String sName, java.lang.String sValue, java.lang.String sDomain, int iAge) Send a cookie to the browser.
protected void	zoneInit() Override this function to initialize local servlet or zone variables (pMaster for example)

Methods inherited from class javax.servlet.http.HttpServlet

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

Methods inherited from class javax.servlet.GenericServlet

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

Methods inherited from class java.lang.Object

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

Field Detail

lServerStarted

public static final long lServerStarted

This is when the server was started

request

protected javax.servlet.http.HttpServletRequest request

The original request object

response

protected javax.servlet.http.HttpServletResponse response

The original response object

osOut

protected java.io.OutputStream osOut

OutputStream to the client

pwOut

protected java.io.PrintWriter pwOut

PrintWriter to the client. Same as osOut, but other interface

sPage

protected java.lang.String sPage

Current servlet that is executed

sZone

protected java.lang.String sZone

The zone of the currently executed servlet

mpRequest

protected com.oreilly.servlet.MultipartRequest mpRequest

Object used for file uploading. See initMultipartRequest(String, int).

bRedirect

protected boolean bRedirect

Remember whether or not there was a redirect executed by the servlet

bGet

protected boolean bGet

Servlets can treat GET and POST differently based on the method they override or by looking at this variable

dbs

public DBSession dbs

Current session

Constructor Detail

ExtendedServlet

public ExtendedServlet()

Method Detail

getCacheKeyModifier

protected java.lang.String getCacheKeyModifier()

Override this method to return any value that would alter the cache. Usually you will want to return here the username, if the user is logged. Or the value of some cookie, if it alters the contents of the caching ...

Returns:

some string that is appended to the caching key.

getCacheAccesses

public static final long getCacheAccesses()

Statistics: get the total number of accesses to pages that could be cached

Returns:

the total number of pages served through this framework

getCacheHits

public static final long getCacheHits()

Statistics: get the number of cache hits

Returns:

the number of pages served from a memory cache by this framework

getServerUptime

public static final java.lang.String getServerUptime()

Statistics: get the server uptime

Returns:

Server uptime, as formatted string

getFrameworkRequests

public static final long getFrameworkRequests()

Framework statistics: get the total number of requests serviced by the framework.

Returns:

total number of requests to servlets that extend the framework

getCacheTimeout

protected long getCacheTimeout()

Method to specify the maximum life time of the cached contents. You should override this method to return the number of seconds for which you know that the contents will not change and it's safe to serve the users the same contents.

This method returns 0 in the default implementation, meaning that the caching is by default disabled for all the servlets.

Returns:

number of seconds for which the contents is valid, default is 0 (cache disabled)

getDomain

protected java.lang.String getDomain()

Method to specify the domain for which the cookies will be set by default (session cookie included). You should override this method to return something like ".acasa.ro".

Returns:

the domain for which the cookies will be set by default

getMaxRunTime

protected int getMaxRunTime()

Method to specify the maximum run time for a page. After this much time (in seconds) the thread that runs the page is forcefully killed. Override this method if you want to allow a maximum execution time different than the default 60 seconds.

In special (read very very unlikely cases) you can return 0 to disable the threads monitoring. This means that this thread is allowed to run forever, and if it does something bad, nobody will catch it. So, you've been warned ...

Returns:

the maximum run time, in seconds, for the current page.

execGet

public abstract void execGet()

A servlet must implement at least this method.

execPost

public void execPost()

By default POST request are executed with the same execGet() function. If you want to execute a different code on POST than on GET you can override this function or you can check the bGet variable.

getApp

protected int getApp()

Get the application number. Each major application should have a different, unique, identifier. This is to distinguish between the sessions, which ones are for which application, when creating statistics. See getOnlineUsers() for example.

Returns:

application unique number

isSessionIPProtected

public boolean isSessionIPProtected()

Flag to set whether or not the session is valid only when used from the first IP that generated the session. In some cases (multiple load-balancing http proxies) this schema might not work.

Returns:

true by default, but can be overriden by actual implementations

setContentType

public void setContentType(java.lang.String sContentType)

If you set the content type to something else than "text/html; charset=UTF-8" and you use the caching mechanism you should use this method instead of directly calling response.setContentType

Parameters:

sContentType -

gets

public final java.lang.String gets(java.lang.String sParam)

Get the value of a parameter as a string.

Parameters:

sParam - the parameter name

Returns:

the string value of this parameter, never null ("" is returned in the worst case)

gets

public final java.lang.String gets(java.lang.String sParam,
                                   java.lang.String sDefault)

Get the value of a parameter as a string.

Parameters:

sParam - the parameter name

sDefault - default value to return in case the value is not defined or is the empty string

Returns:

the string value of this parameter

geti

public final int geti(java.lang.String sParam,
                      int defaultVal)

Get the value of a parameter as an integer value. If there is a parsing error then return the given default value.

Parameters:

sParam - the name of the parameter

defaultVal - default value to return in case of an error

Returns:

parsed value of the parameter, or the defaultValue if parameter is missing or is not an integer value representation

geti

public final int geti(java.lang.String sParam)

Get the value of a parameter as an integer value. If there is a parsing error then the value 0 will be returned.

Parameters:

sParam - name of the parameter

Returns:

parsed value of the request parameter, or 0 if there is any error in parsing, parameter not existing etc

getl

public final long getl(java.lang.String sParam,
                       long defaultVal)

Get the value of a parameter as a long value. If there is a parsing error then return the given default value.

Parameters:

sParam - the name of the parameter

defaultVal - default value to return in case of an error

Returns:

parsed value of the parameter, or the defaultValue if parameter is missing or is not a long value representation

getl

public final long getl(java.lang.String sParam)

Get the value of a parameter as a long value. If there is a parsing error then the value 0 will be returned.

Parameters:

sParam - name of the parameter

Returns:

parsed value of the request parameter, or 0 if there is any error in parsing, parameter not existing etc

getf

public final float getf(java.lang.String sParam,
                        float defaultVal)

Get the value of a parameter as a float value. If there is a parsing error then return the given default value.

Parameters:

sParam - the name of the parameter

defaultVal - default value to return in case of an error

Returns:

parsed value of the parameter, or the defaultValue if parameter is missing or is not a float value representation

getf

public final float getf(java.lang.String sParam)

Get the value of a parameter as a float value. If there is a parsing error then the value 0 will be returned.

Parameters:

sParam - name of the parameter

Returns:

parsed value of the request parameter, or 0 if there is any error in parsing, parameter not existing etc

getd

public final double getd(java.lang.String sParam,
                         double defaultVal)

Get the value of a parameter as a double value. If there is a parsing error then return the given default value.

Parameters:

sParam - the name of the parameter

defaultVal - default value to return in case of an error

Returns:

parsed value of the parameter, or the defaultValue if parameter is missing or is not a double value representation

getd

public final double getd(java.lang.String sParam)

Get the value of a parameter as a double value. If there is a parsing error then the value 0 will be returned.

Parameters:

sParam - name of the parameter

Returns:

parsed value of the request parameter, or 0 if there is any error in parsing, parameter not existing etc

getValues

public final java.lang.String[] getValues(java.lang.String sParam)

Get all the values of a parameter.

Parameters:

sParam -

Returns:

values array, possibly empty but never null

redirect

protected final boolean redirect(java.lang.String sURL)

Wrapper method for the actual redirect, that keeps track if there was such an opperation. This is done in order to disable the caching in this case.

Parameters:

sURL - the URL to send the browser to

Returns:

true if the operation was successfully, false if there was an error

esc

public static final java.lang.String esc(java.lang.String s)

Produce safe SQL strings. Wrapper for Format.escSQL(String) call.

Parameters:

s - the string to escape

Returns:

the SQL-safe representation

escHtml

public static final java.lang.String escHtml(java.lang.String s)

Produce save HTML strings. Wrapper for Format.escHtml(String) call.

Parameters:

s - the string to escape

Returns:

the HTML-safe representation

getCookie

public final java.lang.String getCookie(java.lang.String sName)

Get the value of a specific cookie

Parameters:

sName - the name of the cookie

Returns:

the value of the cookie, or "" if there was an error (cookie not existing ...)

setCookie

public boolean setCookie(java.lang.String sName,
                         java.lang.String sValue)

Send a session cookie to the browser. The cookie is made available to the domain returned by the getDomain() function

Parameters:

sName - name of the cookie

sValue - value

Returns:

true on success, false on error

setCookie

public boolean setCookie(java.lang.String sName,
                         java.lang.String sValue,
                         int iAge)

Send a cookie to the browser. The cookie is made available to the domain returned by the getDomain() function

Parameters:

sName - name of the cookie

sValue - value

iAge - lifetime of the cookie, in seconds, relative to "now". Negative=session cookie. Zero=delete this cookie.

Returns:

true on success, false on error

setCookie

public boolean setCookie(java.lang.String sName,
                         java.lang.String sValue,
                         java.lang.String sDomain,
                         int iAge)

Send a cookie to the browser.

Parameters:

sName - name of the cookie

sValue - value

sDomain - the domain for which this cookie is set

iAge - lifetime of the cookie, in seconds, relative to "now". Negative=session cookie. Zero=delete this cookie.

Returns:

true on success, false on error

doInit

protected void doInit()

This is a hook provided for the servlets as a generic way to initialize their local variables, do authentication and so on. Generally this is implemented in each zone's local master servlet and checks for user's session. You probably want to override this. Use this to initialize only the variables used in getCacheTimeout() and getCacheKeyModifier(). For IO-related variables (eg pMaster) use zoneInit().

zoneInit

protected void zoneInit()

Override this function to initialize local servlet or zone variables (pMaster for example)

doGet

public final void doGet(javax.servlet.http.HttpServletRequest req,
                        javax.servlet.http.HttpServletResponse resp)

Original request from servlet engine comes through here. It will be handled internally.

Overrides:

doGet in class javax.servlet.http.HttpServlet

Parameters:

req - servlet request

resp - servlet response

doPost

public final void doPost(javax.servlet.http.HttpServletRequest req,
                         javax.servlet.http.HttpServletResponse resp)

Original request from servlet engine comes through here. It will be handled internally.

Overrides:

doPost in class javax.servlet.http.HttpServlet

Parameters:

req - servlet request

resp - servlet response

initMultipartRequest

protected final boolean initMultipartRequest(java.lang.String sTempDir,
                                             int iFileSizeLimit)

This method should be called when the servlet expects a file upload from the client. It will initialize the mpRequest object. If the file is too big or there is another problem uploading the file then the method will return false, if everything is ok then it will return true.

Parameters:

sTempDir - temporary folder for the files that are uploaded

iFileSizeLimit - maximum size of a file

Returns:

true if the request is indeed a file upload, the file size is <= iFileSizeLimit and the weather outside is fine

getOnlineUsers

protected int getOnlineUsers()

Get the number of online users for the current application. See getApp() for this.

Returns:

the number of online users (active sessions)

getHostName

public final java.lang.String getHostName()

Get the nice host name for the client that made the current request. If possible this will return the reversed DNS name, or if this is not available the plain IP address.

Returns:

client's address

getHostAddr

public final java.lang.String getHostAddr()

Get the client host address (IP).

Returns:

the client's IP address

getCurrentPage

public final java.lang.String getCurrentPage()

Compose the full URL to the current page. Use this when you want for example to force the user to first authenticate, and when this operation succeeds to return it to the page it was initially trying to access.

Returns:

the URL of the current page

See Also:

DBSession.setLastPage(String)

log

public void log(java.lang.String sMessage)

Override the method provided by the Java Servlet Api to log messages as DEBUG

Overrides:

log in class javax.servlet.GenericServlet

See Also:

GenericServlet.log(java.lang.String), log(int, String)

log

public void log(int level,
                java.lang.String sMessage)

Log messages with a given level of the problem. See Log for possible logging levels.

Parameters:

level - problem level

sMessage - error message

log

public void log(int level,
                java.lang.String sMessage,
                java.lang.Object o)

Special logging for exceptions. It can be used to log any other objects too, but if the passed object is not a Throwable instance it will simply call toString() for it and that's it.

Parameters:

level - problem level

sMessage - error message

o - object to be logged, special case when the object is a Throwable instance

isLoggable

public boolean isLoggable(int iLevel)

Find out whether or not the current page is able to log this level of debug. You should check for this function's result prior to actually logging something big or something that would require some processing power.

Parameters:

iLevel - desired logging level

Returns:

true if a message at this level would be logged, false if not