uk.co.weft.htform
Class Servlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          uk.co.weft.maybeupload.MaybeUploadServlet
              uk.co.weft.htform.Servlet

All Implemented Interfaces:

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

Direct Known Subclasses:

DataTable, Graphic, ICalServlet, Stylist, Thumbnail, WithExceptionHandlerServlet

public abstract class Servlet

extends MaybeUploadServlet

implements ResourceConsumer

This is a basic servlet which produces nothing; to produce anything, specialise generateContent(). A Servlet may have a database connection -- it has all the glue. but it does not whinge if it hasn't got one. Specialised sub-classes do that whinging.

A note on the security model: this class does not currently support database level security, as connections are cached in a pool for re-use and may be re-used in other sessions with other browsers. Prepared queries are also attached to sessions in the public pool. If security is a consideration use AuthenticatedForm.

This class (and consequently all servlets which are subclasses of this class) know about the following configuration parameters:

content_type

String: the mime type of the output of this servlet. Optional. Defaults to 'text/html'.

cookie_domain

String: the domain for cookies created by this servlet. Usually the hostname of the server. Must be prefixed by a dot. Optional. No default.

cookie_path

String: the path for cookies created by this servlet. Usually the name of the webapp of which this servlet forms a part. Optional. Defaults to "/" (anywhere on this server)

cookie_ttl

Integer: the time to live for cookies created by this servlet, in seconds. Optional, defaults to one day.

cookies

String: a space separated list of initial cookies to set up, if any. Note that you can only specify the cookie names, the values must come from the context (although as the config forms part of the context you could specify them separately in the config). Optional. No default.

countrycode

String: the countrycode to use to calculate the locale. Optional. Defaults to UK.

driver_name

String: the class name of the JDBC database driver to use. Required if a database is used. No default.

db_password

String: the password to be used to communicate with the database. Optional, but see AuthenticatedForm. May be passed in the context.

db_username

String: the username to be used to communicate with the database. Optional, but see AuthenticatedForm. May be passed in the context.

db_url

String: the JDBC URL to use to communicate with the database. Required if a database is used. No default.

debug

Boolean. If 'true', turn on context dumps when exceptions are reported, and insert other debugging information as comments. WARNING! This is extremely insecure! You absolutely should not use this option on a production system!

first_time_redirect

String: the relative URL of a servlet to redirect to if this is the first time this webapp has been used. Optional. Defaults to servlet/firsttime.

identity

String: the identity string to be returned by this servlet in the getServletInfo() call. Optional. Defaults to Created using Jacquard

language

String: the language to use to calculate the locale. Optional. Defaults to "EN" (English).

parse_path_info

String: space separated list of tokens which may safely be parsed out of the URL path-part. If set to (e.g.) foo and the servlet has an appropriate servlet mapping, http://host/webapp/servlet/foo_bar.html is handled in exactly the same way as http://host/webapp/servlet?foo=bar. Optional. No default (i.e. the path info will not be parsed).

resource_bundle_name

String: the base name of the resource bundle which will be used for internationalisation of messages, etc. Optional. Defaults to jacquard. The appropriate resouce bundle must of course be on the classpath.

timezone

String: the timezone to use to parse and display dates and times. Optional. Defaults to "BST".

Note that as of revision 1.24 (Jacquard 1.4.6), Servlet (and all classes inheriting from it) will support Secure Sockets Layer (HTTPS) connections, but only if you are using Java 1.4 or have JSSE loaded. If you don't, the SSL code will report this in the log on startup, but will not interfere with standard HTTP operation.

Version:

$Revision: 1.51.4.5 $ This revision: $Author: simon $

Author:

Simon Brooke

See Also:

AuthenticatedForm, Serialized Form

Field Summary

protected java.util.GregorianCalendar	calendar handy to have a calendar around to help with manipulating dates
protected javax.servlet.ServletConfig	conf My configuration object, passed to me when I was created
protected java.lang.String	contentType the MIME type of my content
static java.lang.String	CONTENTTYPECONFIGTOKEN a configuration token on which I will seek my content type specifier in my configuraton
protected java.lang.String	cookieDomain the domain for my cookies
protected java.lang.String	cookiePath the path for my cookies
static java.lang.String	COOKIESCONFIGTOKEN a configuration token on which I will seek the names of any initial cookies to set in my configuraton
protected int	cookieTTL the default time-to-live of cookies
protected java.lang.String	dbPassword and password to connect me to the database, if any
protected java.lang.String	dbUrl where to find the database: there is no safe default.
protected java.lang.String	dbUsername the username...
protected boolean	debug print additional diagnostics on error
static java.lang.String	DEBUGCONFIGTOKEN a configuration token on which I will check whether to run in debugging mode
protected java.lang.String	driverName the classname of my database driver, if any
protected boolean	embedded whether I am embedded in an existing (e.g.
protected java.util.Locale	here where we are operating - defaults to UK english
protected java.lang.String	identity my identity
static java.lang.String	localeMagicToken Deprecated. use LOCALEMAGICTOKEN
static java.lang.String	LOCALEMAGICTOKEN the magic token on which to store the request locale in the context, once we have computed it.
static java.lang.String	outputStreamMagicToken Deprecated. use OUTPUTSTREAMMAGICTOKEN
static java.lang.String	OUTPUTSTREAMMAGICTOKEN The magic token on which I store my output stream in the context
protected Context	parsePathInfo a hashtable of keys I'm prepared to parse out of the path info string
static java.lang.String	PATHINFOMAGICTOKEN the magic token on which I will store the path info in the context
protected boolean	ready Flag to say whether second-stage initialisation is complete.
static java.lang.String	redirectMagicToken Deprecated. use REDIRECTMAGICTOKEN
static java.lang.String	REDIRECTMAGICTOKEN The magic token on which to store where to redirect to after a service.
static java.lang.String	requestMagicToken Deprecated. use REQUESTMAGICTOKEN
static java.lang.String	REQUESTMAGICTOKEN the token on which I store my request in the context
protected java.lang.String	resourceBundleName the name of the resource bundle I will search for resources.
static java.lang.String	responseMagicToken Deprecated. use RESPONSEMAGICTOKEN
static java.lang.String	RESPONSEMAGICTOKEN the token on which I store my response in the context
static java.lang.String	servletMagicToken Deprecated. use SERVLETMAGICTOKEN
static java.lang.String	SERVLETMAGICTOKEN the token on which I store my servlet in the context
static java.lang.String	sessionMagicToken Deprecated. use SESSIONMAGICTOKEN
static java.lang.String	SESSIONMAGICTOKEN the token on which I store my session in the context
static java.lang.String	USEHTTPSCONFIGTOKEN a token in which I shall look in my config for whether or not to handle HTTPS in the Servlet.
protected java.util.TimeZone	zone the timezone in which we are operating -defaults to BST

Fields inherited from class uk.co.weft.maybeupload.MaybeUploadServlet

allowOverwrite, maxUpload, saveUploadedFilesToDisk, silentlyRename, uploadDir, uploadDirPath, uploadDirURL

Fields inherited from interface uk.co.weft.htform.ResourceConsumer

RESOURCEBUNDLEMAGICTOKEN

Constructor Summary

Servlet()

Method Summary

protected void	addCookie(java.lang.String name) To use cookies, add named cookies using this method; do this once, at initialisation time, not each service.
protected void	addCookie(java.lang.String name, int ttl) add a new cookie with this expiration period in seconds
protected Context	coerceCookiesToContext(javax.servlet.http.HttpServletRequest req) Coerce cookies from a servlet request to a context, so we can handle them generically
protected Context	coerceToContext(javax.servlet.http.HttpSession other) Coerce this HTTPSession to a Context, so we can handle it generically
protected Context	coerceToContext(javax.servlet.ServletConfig other) Coerce this ServletConfig to a Context, so that we can handle it generically
protected Context	coerceToContext(javax.servlet.ServletContext other) This is where terminology really gets confusing, and vague names like 'context' don't really help: ServletContext is a Servlet 2.2 spec term which refers to what JServ called a servlet zone, which contains a configuration namespace, whereas our Context is just a namespace.
protected Context	coerceToContext(javax.servlet.ServletRequest other) Coerce this servlet request to a Context, so we can handle it generically; if I accept values passed in the pathInfo, parse for them as well (first)
protected java.net.URL	coerceToUrl(java.lang.String spec) coerce this string to a valid URL.
protected Context	createContext(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Create a context object.
protected void	doGet(MaybeUploadRequestWrapper req, javax.servlet.http.HttpServletResponse res) Really perform service of an HTTP GET request, by printing myself on the response stream
protected void	doPost(MaybeUploadRequestWrapper req, javax.servlet.http.HttpServletResponse res) Really perform service of an HTTP POST request, by printing myself on the response stream
protected Context	fixupMagicValues(Context context, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Fix up the magic values stored on the context by this class.
protected abstract void	generateContent(Context context) Specialise! Do not use! Output the whole document including headers
java.util.Calendar	getCalendar() Return my calendar, surprisingly enough; this contains my localisation stuff.
protected java.lang.String	getContentType(Context context) Return my content type in this context.
boolean	getDebug()
java.util.Locale	getLocale(Context context) get the client-side locale if it can be deduced from the context, else server side.
javax.servlet.ServletOutputStream	getOutputStream(Context context) a convenience method for getting hold of the ServletOutputStream I should have put into the context -- asuming this context is mine, of course
java.lang.Object	getResource(java.lang.String key, Context context) Deprecated. i18n code is still experimental and the only call I commit to supporting in the longer term is grs(String,Context)
java.lang.String	getResourceString(java.lang.String key, Context context) Deprecated. i18n code is still experimental and the only call I commit to supporting in the longer term is grs(String,Context)
java.lang.String	getServletInfo() tell the world about me.
java.lang.String	grs(java.lang.String key) Deprecated. use grs(String,Context)
java.lang.String	grs(java.lang.String key, Context context) shorthand for getResourceString; identical to it.
protected void	handleAction(Context context) Intended to handle actions implied by the context before the page is served; for example, different submit buttons with different actions.
protected void	handleCookies(Context context) Sort out the business of sending and receiving cookies
boolean	handleRedirect(Context context) Set up redirect headers if context contains a valid URL as the value of redirectMagicToken; return true in this case.
void	init(Context config) Basic initialisation, taking my configuration from this Context
void	init(javax.servlet.ServletConfig config) Initialisation: Set up my variables from my configuration.
protected void	makeReady(Context context) Second-stage initialisation hook.
protected void	outputRedirectBlock(Context context) Possibly output a stub HTML page with a 'refresh' meta.
void	setCookieValues(Context context) To use cookies, add named cookies using addCookie(); do this once, at initialisation time, not each service.
protected void	storeOnSession(Context context, java.lang.String key, java.lang.String value) Deprecated. still experimental; may not be supported in future
protected void	whinge(javax.servlet.ServletOutputStream out, java.lang.Exception e) Deprecated. you really, really ought to be passing a context
protected void	whinge(javax.servlet.ServletOutputStream out, java.lang.Exception e, Context context) Last line-of-defence error reporter.

Methods inherited from class uk.co.weft.maybeupload.MaybeUploadServlet

doDelete, doHead, doOptions, doPut, doTrace, getUploadDir, getUploadURL, service

Methods inherited from class javax.servlet.http.HttpServlet

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

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletName, init, log, log

Methods inherited from class java.lang.Object

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

Field Detail

CONTENTTYPECONFIGTOKEN

public static final java.lang.String CONTENTTYPECONFIGTOKEN

a configuration token on which I will seek my content type specifier in my configuraton

See Also:

Constant Field Values

COOKIESCONFIGTOKEN

public static final java.lang.String COOKIESCONFIGTOKEN

a configuration token on which I will seek the names of any initial cookies to set in my configuraton

See Also:

Constant Field Values

DEBUGCONFIGTOKEN

public static final java.lang.String DEBUGCONFIGTOKEN

a configuration token on which I will check whether to run in debugging mode

Since:

Jacquard 1.10.12

See Also:

Constant Field Values

LOCALEMAGICTOKEN

public static final java.lang.String LOCALEMAGICTOKEN

the magic token on which to store the request locale in the context, once we have computed it. The value I put there will be a java.util.Locale and you can rely on this unless you break it

See Also:

Constant Field Values

OUTPUTSTREAMMAGICTOKEN

public static final java.lang.String OUTPUTSTREAMMAGICTOKEN

The magic token on which I store my output stream in the context

See Also:

Constant Field Values

PATHINFOMAGICTOKEN

public static final java.lang.String PATHINFOMAGICTOKEN

the magic token on which I will store the path info in the context

See Also:

Constant Field Values

REDIRECTMAGICTOKEN

public static final java.lang.String REDIRECTMAGICTOKEN

The magic token on which to store where to redirect to after a service. If you set this to a URL in (for example) the store( Context) method of a TableWrapperForm, after storing it will cause the browser to redirect to that URL

See Also:

Constant Field Values

REQUESTMAGICTOKEN

public static final java.lang.String REQUESTMAGICTOKEN

the token on which I store my request in the context

See Also:

Constant Field Values

RESPONSEMAGICTOKEN

public static final java.lang.String RESPONSEMAGICTOKEN

the token on which I store my response in the context

See Also:

Constant Field Values

SERVLETMAGICTOKEN

public static final java.lang.String SERVLETMAGICTOKEN

the token on which I store my servlet in the context

See Also:

Constant Field Values

SESSIONMAGICTOKEN

public static final java.lang.String SESSIONMAGICTOKEN

the token on which I store my session in the context

See Also:

Constant Field Values

USEHTTPSCONFIGTOKEN

public static final java.lang.String USEHTTPSCONFIGTOKEN

a token in which I shall look in my config for whether or not to handle HTTPS in the Servlet. You almost certainly don't want to do this, it is better handled by Apache.

Since:

Jacquard 1.10.19; prior to that HTTPS code was included anyway.

See Also:

Constant Field Values

requestMagicToken

public static final java.lang.String requestMagicToken

Deprecated. use REQUESTMAGICTOKEN

the token on which I store my request in the context

See Also:

Constant Field Values

responseMagicToken

public static final java.lang.String responseMagicToken

Deprecated. use RESPONSEMAGICTOKEN

the token on which I store my response in the context

See Also:

Constant Field Values

servletMagicToken

public static final java.lang.String servletMagicToken

Deprecated. use SERVLETMAGICTOKEN

the token on which I store my servlet (myself) in the context

See Also:

Constant Field Values

sessionMagicToken

public static final java.lang.String sessionMagicToken

Deprecated. use SESSIONMAGICTOKEN

the token on which I store my session in the context

See Also:

Constant Field Values

outputStreamMagicToken

public static final java.lang.String outputStreamMagicToken

Deprecated. use OUTPUTSTREAMMAGICTOKEN

The magic token on which I store my output stream in the context

See Also:

Constant Field Values

redirectMagicToken

public static final java.lang.String redirectMagicToken

Deprecated. use REDIRECTMAGICTOKEN

The magic token on which to store where to redirect to after a service. If you set this to a URL in (for example) the store( Context) method of a TableWrapperForm, after storing it will cause the browser to redirect to that URL.

See Also:

Constant Field Values

localeMagicToken

public static final java.lang.String localeMagicToken

Deprecated. use LOCALEMAGICTOKEN

the magic token on which to store the request locale in the context, once we have computed it. The value I put there will be a java.util.Locale and you can rely on this unless you break it.

See Also:

Constant Field Values

parsePathInfo

protected Context parsePathInfo

a hashtable of keys I'm prepared to parse out of the path info string

calendar

protected java.util.GregorianCalendar calendar

handy to have a calendar around to help with manipulating dates

here

protected java.util.Locale here

where we are operating - defaults to UK english

conf

protected javax.servlet.ServletConfig conf

My configuration object, passed to me when I was created

contentType

protected java.lang.String contentType

the MIME type of my content

cookieDomain

protected java.lang.String cookieDomain

the domain for my cookies

cookiePath

protected java.lang.String cookiePath

the path for my cookies

dbPassword

protected java.lang.String dbPassword

and password to connect me to the database, if any

dbUrl

protected java.lang.String dbUrl

where to find the database: there is no safe default.

dbUsername

protected java.lang.String dbUsername

the username...

driverName

protected java.lang.String driverName

the classname of my database driver, if any

identity

protected java.lang.String identity

my identity

resourceBundleName

protected java.lang.String resourceBundleName

the name of the resource bundle I will search for resources. By default, 'jacquard'

zone

protected java.util.TimeZone zone

the timezone in which we are operating -defaults to BST

debug

protected boolean debug

print additional diagnostics on error

embedded

protected boolean embedded

whether I am embedded in an existing (e.g. JHTML) page

ready

protected boolean ready

Flag to say whether second-stage initialisation is complete. Problem is many servlets have initialisation things they can only do when they have a connection, and at init() time they don't have. This is a hook to allow them to do that. You really, really do not want to mess with this.

cookieTTL

protected int cookieTTL

the default time-to-live of cookies

Constructor Detail

Servlet

public Servlet()

Method Detail

getCalendar

public java.util.Calendar getCalendar()

Return my calendar, surprisingly enough; this contains my localisation stuff.

Returns:

my calendar.

setCookieValues

public void setCookieValues(Context context)

To use cookies, add named cookies using addCookie(); do this once, at initialisation time, not each service. To set cookies values at service time, specialise this method -- the default one does nothing. Simply use context.setValue( name_of_cookie).

Parameters:

context - the context in which the cookie values will be set.

getDebug

public boolean getDebug()

Returns:

the current value of my debug field

getLocale

public java.util.Locale getLocale(Context context)

get the client-side locale if it can be deduced from the context, else server side.

getOutputStream

public javax.servlet.ServletOutputStream getOutputStream(Context context)

a convenience method for getting hold of the ServletOutputStream I should have put into the context -- asuming this context is mine, of course

Parameters:

context - the context to look in for the stream

Returns:

the output stream if there is one in the context and it is a ServletOutputStream, else null

getResource

public java.lang.Object getResource(java.lang.String key,
                                    Context context)

Deprecated. i18n code is still experimental and the only call I commit to supporting in the longer term is grs(String,Context)

return the value of the resource with the given key as whatever sort of object it happens to be. In the end if the resource cannot be found throw an exception.

Specified by:

getResource in interface ResourceConsumer

Parameters:

key - the key to search for

context - teh context in which to make request; may contain locale information

Returns:

a locale-sepecific value for key, if found, else the key itself.

getResourceString

public java.lang.String getResourceString(java.lang.String key,
                                          Context context)

Deprecated. i18n code is still experimental and the only call I commit to supporting in the longer term is grs(String,Context)

return as a string the value of the resource with the given key. If in the end the resource cannot be found just return the key.

Specified by:

getResourceString in interface ResourceConsumer

Parameters:

key - the key to search for

context - the context in which to make this call (may contain locale information)

Returns:

a locale-sepecific value for key, if found, else the key itself.

getServletInfo

public java.lang.String getServletInfo()

tell the world about me.

Specified by:

getServletInfo in interface javax.servlet.Servlet

Returns:

my identity string.

grs

public java.lang.String grs(java.lang.String key,
                            Context context)

shorthand for getResourceString; identical to it.

Specified by:

grs in interface ResourceConsumer

See Also:

#getResourceString(String)

grs

public java.lang.String grs(java.lang.String key)

Deprecated. use grs(String,Context)

In Jacquard 1.8 I had a one arg grs(); this is here for backwards compatibility only. I still haven't fully sussed the best way to do i18n, and this way only does server-side i18n which definitely isn't good enough. But since I published the API I'd better support it.

Specified by:

grs in interface ResourceConsumer

handleRedirect

public boolean handleRedirect(Context context)
                       throws java.net.MalformedURLException,
                              java.io.IOException

Set up redirect headers if context contains a valid URL as the value of redirectMagicToken; return true in this case. If no value or value not a valid URL return false.

Parameters:

context - the context for this service

Returns:

a flag indicating whether a redirect has been handled

Throws:

java.io.IOException - may be passed through from outputRedirectBlock

java.net.MalformedURLException - if value of redirectMagicToken in context is not a valid (relative) URL

init

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

Initialisation: Set up my variables from my configuration. If a database connection is specified in my config, attempt to set it up. The database connection may fail. If it does, it fails silently; a Servlet is not by default guaranteed to have a connection. Subclasses which do require a connection should call super.init(), and then call try getConnection(): if getConnection() throws an Exception, then the subclass should throw an UnavailableException

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class MaybeUploadServlet

Parameters:

config - my Servlet configuration.

Throws:

javax.servlet.ServletException - doesn't; thing which specialise me may

init

public void init(Context config)
          throws InitialisationException

Basic initialisation, taking my configuration from this Context

Throws:

InitialisationException

getContentType

protected java.lang.String getContentType(Context context)

Return my content type in this context. The default method simply returns the value of the contentType iv; specialise if you need to compute the content type.

Returns:

my content type in this context.

addCookie

protected void addCookie(java.lang.String name)

To use cookies, add named cookies using this method; do this once, at initialisation time, not each service. To set cookies values at service time, specialise setCookieValues() q.v. creates a new cookie object and adds it to my cookies Vector. Do not use the cookie mechanisms in htform unless to pass values to non-htform dynamic content. Simply put persistent values on the Context instead.

Parameters:

name - the name of the cookie to set - also, the name which contexts will be searched on to provide the cookie value.

addCookie

protected void addCookie(java.lang.String name,
                         int ttl)

add a new cookie with this expiration period in seconds

Parameters:

name - the name of the cookie to set - also, the name which contexts will be searched on to provide the cookie value.

ttl - time to live for this cookie in seconds.

coerceCookiesToContext

protected Context coerceCookiesToContext(javax.servlet.http.HttpServletRequest req)

Coerce cookies from a servlet request to a context, so we can handle them generically

Parameters:

req - the ServletRequest to coerce.

Returns:

the context.

coerceToContext

protected Context coerceToContext(javax.servlet.ServletContext other)

This is where terminology really gets confusing, and vague names like 'context' don't really help: ServletContext is a Servlet 2.2 spec term which refers to what JServ called a servlet zone, which contains a configuration namespace, whereas our Context is just a namespace. Note that the code of this method is identical to the ServletConfig variant... I do wish Sun had required these things to implement (

Parameters:

other - the ServletContext to coerce.

Returns:

the context.

See Also:

Map

coerceToContext

protected Context coerceToContext(javax.servlet.ServletConfig other)

Coerce this ServletConfig to a Context, so that we can handle it generically

Parameters:

other - the ServletConfig to coerce.

Returns:

the context.

coerceToContext

protected Context coerceToContext(javax.servlet.http.HttpSession other)
                           throws javax.servlet.ServletException

Coerce this HTTPSession to a Context, so we can handle it generically

Parameters:

other - the HttpSession to coerce.

Returns:

a context

Throws:

javax.servlet.ServletException

coerceToContext

protected Context coerceToContext(javax.servlet.ServletRequest other)
                           throws javax.servlet.ServletException

Coerce this servlet request to a Context, so we can handle it generically; if I accept values passed in the pathInfo, parse for them as well (first)

Parameters:

other - the ServletRequest to coerce.

Returns:

the context.

Throws:

javax.servlet.ServletException

createContext

protected Context createContext(javax.servlet.http.HttpServletRequest request,
                                javax.servlet.http.HttpServletResponse response)
                         throws DataStoreException,
                                javax.servlet.ServletException

Create a context object. Done in a separate method so that subclasses can do their own special thing in populating the context; however, rather than specialising this it may be better (and simpler) to specialise fixupMagicValues q.v.

Note that it is this class which establishes the precedence (masking) of values as they appear in the context, namely:

• Values in the request (POST or GET values) are prefered to all others
• Values passed as cookies are next preferred
• Values set in the session are next and can be masked by request or cookie values
• Configuration values are least preferred and may be masked by anything else. Note that if you have a clash between a widget name and a configuration value you want to use, you are in trouble...

Parameters:

request - the request object for this service

response - the response object for this service

Returns:

a context constructed around this request and response

Throws:

No - , I know this doesn't actually throw an exception. But things which specialise me may want to.

DataStoreException

javax.servlet.ServletException

See Also:

fixupMagicValues(uk.co.weft.dbutil.Context, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

fixupMagicValues

protected Context fixupMagicValues(Context context,
                                   javax.servlet.http.HttpServletRequest request,
                                   javax.servlet.http.HttpServletResponse response)

Fix up the magic values stored on the context by this class. Specialisations are strongly urged to start with a call to super.fixupMagicValues() - do this unless you're really sure you know what you are doing, otherwise horrible things will happen. You have been warned.

Parameters:

context - the context in which the values are to be fixed

request - the request for this service

response - the response to this request

Returns:

the same context.

generateContent

protected abstract void generateContent(Context context)
                                 throws java.lang.Exception

Specialise! Do not use! Output the whole document including headers

Parameters:

context - the context in which to generate this content.

Throws:

java.lang.Exception

coerceToUrl

protected java.net.URL coerceToUrl(java.lang.String spec)
                            throws java.net.MalformedURLException

coerce this string to a valid URL.

Parameters:

spec - a string representing a URL or a full or relative file path name; if relative, relative to the document root of my web-app.

Returns:

a URL representation of the spec

Throws:

java.net.MalformedURLException - if the string cannot be coerced to a valid URL

doGet

protected void doGet(MaybeUploadRequestWrapper req,
                     javax.servlet.http.HttpServletResponse res)
              throws javax.servlet.ServletException,
                     java.io.IOException

Really perform service of an HTTP GET request, by printing myself on the response stream

Overrides:

doGet in class MaybeUploadServlet

Parameters:

req - the request object for this service

res - the response object for this service

Throws:

javax.servlet.ServletException

java.io.IOException

doPost

protected void doPost(MaybeUploadRequestWrapper req,
                      javax.servlet.http.HttpServletResponse res)
               throws javax.servlet.ServletException,
                      java.io.IOException

Really perform service of an HTTP POST request, by printing myself on the response stream

Overrides:

doPost in class MaybeUploadServlet

Parameters:

req - a request wrapper which know how to handle upload

res - a standard servlet response

Throws:

javax.servlet.ServletException

java.io.IOException

handleAction

protected void handleAction(Context context)
                     throws java.lang.Exception

Intended to handle actions implied by the context before the page is served; for example, different submit buttons with different actions. Specialise, if you want to do any action handling. Default does nothing.

Parameters:

context - the context for this service.

Throws:

doesn - 't actually throw an exception but things which specialise it may want to

java.lang.Exception

See Also:

Form.handleAction(uk.co.weft.dbutil.Context)

handleCookies

protected void handleCookies(Context context)
                      throws javax.servlet.ServletException,
                             java.io.IOException

Sort out the business of sending and receiving cookies

Parameters:

context - the context for this service, from which cookie values will be read and into which cookie values will be set.

Throws:

javax.servlet.ServletException

java.io.IOException

makeReady

protected void makeReady(Context context)
                  throws DataStoreException,
                         javax.servlet.ServletException

Second-stage initialisation hook. Problem is many servlets have initialisation things they can only do when they have a connection, and at init() time they don't have. This is a hook to allow them to do that. Specialisations must set the flag, and are advised to do so with a super.makeReady() call.

Parameters:

context - my first context.

Throws:

Specialisations - may want to throw exceptions for various reasons, which is why the possibility of a ServletException or DataStoreException is provided for.

DataStoreException

javax.servlet.ServletException

outputRedirectBlock

protected void outputRedirectBlock(Context context)
                            throws java.io.IOException

Possibly output a stub HTML page with a 'refresh' meta. Should be redundent, because only output it a type 302 response has already been sent, so should never be seen... but does no harm

Parameters:

context - the context for this service

Throws:

java.io.IOException - if output barfs.

storeOnSession

protected void storeOnSession(Context context,
                              java.lang.String key,
                              java.lang.String value)
                       throws DataStoreException

Deprecated. still experimental; may not be supported in future

Sometimes the best way to pass a value around is to store it explicitly on the session. Using hidden widgets to pass values around is insecure because users can inspect page source, and is in any case not persistent. Values stored on the session can of course be retrieved by context.get(String) but will be masked there by values from cookies or the service.

Parameters:

context - the context in which this is being passed around

key - the key against which the value should be stored

value - the value to store

Throws:

DataStoreException - if no session can be found; may become more specialised exception in mature implementation

Since:

Jacquard 1.10.10

whinge

protected void whinge(javax.servlet.ServletOutputStream out,
                      java.lang.Exception e,
                      Context context)
               throws javax.servlet.ServletException

Last line-of-defence error reporter.

Parameters:

out - an output stream to print on

e - an exception to whinge about

context - the context in which the problem occurred.

Throws:

javax.servlet.ServletException

whinge

protected void whinge(javax.servlet.ServletOutputStream out,
                      java.lang.Exception e)
               throws javax.servlet.ServletException,
                      java.io.IOException

Deprecated. you really, really ought to be passing a context

Last line-of-defence error reporter.

Parameters:

out - an output stream to print on

e - an exception to whinge about

Throws:

javax.servlet.ServletException

java.io.IOException