ServletRequest Interface
Defines an object to provide
client request information to a servlet. The servlet container creates a ServletRequest object and passes it as an argument to the
servlet's service method.A
ServletRequest object provides data including parameter
name and values, attributes, and an input stream. Interfaces that extend ServletRequest can provide additional protocol-specific
data (for example, HTTP data is provided by HttpServletRequest.|
Method Summary
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java.lang.Object |
getAttribute
(java.lang.String name) Returns the value of the named attribute as an Object, or null if no attribute of the
given name exists. |
java.util.Enumeration |
getAttributeNames
() Returns an Enumeration containing the names of the attributes available to this
request. |
java.lang.String |
|
int |
getContentLength
() Returns the length, in bytes, of the request body and made available by the input stream, or -1 if the length is not known. |
java.lang.String |
getContentType
() Returns the MIME type of the body of the request, or null if the type is not known. |
java.lang.String |
getLocalAddr
() Returns the Internet Protocol (IP) address of the interface on which the request was received. |
java.util.Locale |
getLocale
() Returns the preferred Locale that the client will accept content in, based on the
Accept-Language header. |
java.util.Enumeration |
getLocales
() Returns an Enumeration of Locale objects indicating, in decreasing order starting with the
preferred locale, the locales that are acceptable to the client based on the
Accept-Language header. |
java.lang.String |
getLocalName
() Returns the host name of the Internet Protocol (IP) interface on which the request was received. |
int |
getLocalPort
() Returns the Internet Protocol (IP) port number of the interface on which the request was received. |
java.lang.String |
getParameter
(java.lang.String name) Returns the value of a request parameter as a String, or null if the parameter does
not exist. |
java.util.Map |
|
java.util.Enumeration |
getParameterNames
() Returns an Enumeration of String objects containing the names of the parameters contained in
this request. |
java.lang.String[] |
getParameterValues
(java.lang.String name) Returns an array of String objects containing all of the values the given request
parameter has, or null if the parameter does not exist. |
java.lang.String |
getProtocol
() Returns the name and version of the protocol the request uses in the formprotocol/majorVersion.minorVersion, for example, HTTP/1.1. |
java.io.BufferedReader |
|
java.lang.String |
getRealPath
(java.lang.String path) Deprecated. As of Version 2.1 of the Java Servlet API, use ServletContext.getRealPath(java.lang.String) instead. |
java.lang.String |
getRemoteAddr
() Returns the Internet Protocol (IP) address of the client or last proxy that sent the request. |
java.lang.String |
getRemoteHost
() Returns the fully qualified name of the client or the last proxy that sent the request. |
int |
getRemotePort
() Returns the Internet Protocol (IP) source port of the client or last proxy that sent the request. |
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getRequestDispatcher
(java.lang.String path) Returns a RequestDispatcher object that acts as a wrapper for
the resource located at the given path. |
|
java.lang.String |
getScheme
() Returns the name of the scheme used to make this request, for example, http, https, orftp. |
java.lang.String |
|
int |
|
boolean |
isSecure
() Returns a boolean indicating whether this request was made using a secure channel, such as HTTPS. |
void |
|
void |
|
void |
setCharacterEncoding
(java.lang.String env) Overrides the name of the character encoding used in the body of this request. |
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Method Detail
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getAttribute
java.lang.Object getAttribute(java.lang.String name)
Returns the value of the named attribute as an
Object, or null if no attribute of the given name exists.
Attributes
can be set two ways. The servlet container may set attributes to make available
custom information about a request. For example, for requests made using HTTPS,
the attribute
javax.servlet.request.X509Certificate can be used to retrieve information on the
certificate of the client. Attributes can also be set programatically usingsetAttribute(java.lang.String, java.lang.Object). This allows information to be embedded
into a request before a RequestDispatcher call.
Attribute
names should follow the same conventions as package names. This specification
reserves names matching
java.*, javax.*,
and sun.*.
Parameters:
name - a String specifying the name of
the attribute
Returns:
an
Object containing the value of the attribute, or null if the attribute does not
exist
getAttributeNames
java.util.Enumeration getAttributeNames()
Returns an
Enumeration containing the names of the attributes available to this
request. This method returns an empty Enumeration if the request has no attributes available to it.
Returns:
an
Enumeration of strings containing the names of the request's attributes
getCharacterEncoding
java.lang.String getCharacterEncoding()
Returns the name of the character encoding used
in the body of this request. This method returns
null if the request does not
specify a character encoding
Returns:
a
String containing the name of the character encoding, or null if the request does not
specify a character encoding
setCharacterEncoding
void setCharacterEncoding(java.lang.String env)
throws java.io.UnsupportedEncodingException
Overrides the name of the character encoding used
in the body of this request. This method must be called prior to reading
request parameters or reading input using getReader(). Otherwise, it has no
effect.
Parameters:
env - String containing the name of
the character encoding.
Throws:
java.io.UnsupportedEncodingException - if this ServletRequest is still in a state where a
character encoding may be set, but the specified encoding is invalid
getContentLength
int getContentLength()
Returns the length, in bytes, of the request body
and made available by the input stream, or -1 if the length is not known. For
HTTP servlets, same as the value of the CGI variable CONTENT_LENGTH.
Returns:
an integer containing the length of the request
body or -1 if the length is not known
getContentType
java.lang.String getContentType()
Returns the MIME type of the body of the request,
or
null if the type is not known. For HTTP servlets, same as the
value of the CGI variable CONTENT_TYPE.
Returns:
a
String containing the name of the MIME type of the request, or null
if the type is not known
getInputStream
ServletInputStream getInputStream()
throws java.io.IOException
Retrieves the body of the request as binary data
using a
ServletInputStream.
Either this method or getReader()may be called
to read the body, not both.
Returns:
a
ServletInputStream object containing the body of the
request
Throws:
java.lang.IllegalStateException - if the getReader() method has already been called for
this requestjava.io.IOException - if an input or output exception occurred
getParameter
java.lang.String getParameter(java.lang.String name)
Returns the value of a request parameter as a
String, or null if the parameter does not exist. Request parameters are extra
information sent with the request. For HTTP servlets, parameters are contained
in the query string or posted form data.
You
should only use this method when you are sure the parameter has only one value.
If the parameter might have more than one value, use
getParameterValues(java.lang.String).
If you
use this method with a multivalued parameter, the value returned is equal to
the first value in the array returned by
getParameterValues.
If the
parameter data was sent in the request body, such as occurs with an HTTP POST
request, then reading the body directly via
getInputStream() or getReader() can interfere with the execution of this
method.
Parameters:
name - a String specifying the name of
the parameter
Returns:
a
String representing the single value of the parameter
See Also:
getParameterNames
java.util.Enumeration getParameterNames()
Returns an
Enumeration of String objects containing the names of the parameters contained in
this request. If the request has no parameters, the method returns an empty Enumeration.
Returns:
an
Enumeration of String objects, each String containing the name of a request parameter; or an emptyEnumeration if the request has no parameters
getParameterValues
java.lang.String[] getParameterValues(java.lang.String name)
Returns an array of
String objects containing all of
the values the given request parameter has, or null if the parameter does not
exist.
If the
parameter has a single value, the array has a length of 1.
Parameters:
name - a String containing the name of
the parameter whose value is requested
Returns:
an array of
String objects containing the parameter's values
See Also:
getParameterMap
java.util.Map getParameterMap()
Returns a java.util.Map of the parameters of this
request. Request parameters are extra information sent with the request. For
HTTP servlets, parameters are contained in the query string or posted form
data.
Returns:
an immutable java.util.Map containing parameter
names as keys and parameter values as map values. The keys in the parameter map
are of type String. The values in the parameter map are of type String array.
getProtocol
java.lang.String getProtocol()
Returns the name and version of the protocol the
request uses in the form protocol/majorVersion.minorVersion,
for example, HTTP/1.1. For HTTP servlets, the value returned is the same as the
value of the CGI variable
SERVER_PROTOCOL.
Returns:
a
String containing the protocol name and version number
getScheme
java.lang.String getScheme()
Returns the name of the scheme used to make this
request, for example,
http, https, or ftp. Different schemes have
different rules for constructing URLs, as noted in RFC 1738.
Returns:
a
String containing the name of the scheme used to make this request
getServerName
java.lang.String getServerName()
Returns the host name of the server to which the
request was sent. It is the value of the part before ":" in the
Hostheader value, if any, or the resolved server
name, or the server IP address.
Returns:
a
String containing the name of the server
getServerPort
int getServerPort()
Returns the port number to which the request was
sent. It is the value of the part after ":" in the
Host header value, if any, or
the server port where the client connection was accepted on.
Returns:
an integer specifying the port number
getReader
java.io.BufferedReader getReader()
throws java.io.IOException
Retrieves the body of the request as character
data using a
BufferedReader. The reader translates
the character data according to the character encoding used on the body. Either
this method or getInputStream() may be called to read the body, not
both.
Returns:
a
BufferedReader containing the body of the request
Throws:
UnsupportedEncodingException - if the character set encoding used is not supported and the
text cannot be decodedjava.io.IOException - if an input or output exception occurred
See Also:
getRemoteAddr
java.lang.String getRemoteAddr()
Returns the Internet Protocol (IP) address of the
client or last proxy that sent the request. For HTTP servlets, same as the
value of the CGI variable
REMOTE_ADDR.
Returns:
a
String containing the IP address of the client that sent the request
getRemoteHost
java.lang.String getRemoteHost()
Returns the fully qualified name of the client or
the last proxy that sent the request. If the engine cannot or chooses not to
resolve the hostname (to improve performance), this method returns the
dotted-string form of the IP address. For HTTP servlets, same as the value of
the CGI variable
REMOTE_HOST.
Returns:
a
String containing the fully qualified name of the client
setAttribute
void setAttribute(java.lang.String name,
java.lang.Object o)
Stores an attribute in this request. Attributes
are reset between requests. This method is most often used in conjunction with
RequestDispatcher.
Attribute
names should follow the same conventions as package names. Names beginning with
If the object passed in is null, the effect is the same as calling
It is warned that when the request is dispatched from the servlet resides in a different web application by
java.*, javax.*, and com.sun.*, are reserved for use by Sun Microsystems. If the object passed in is null, the effect is the same as calling
removeAttribute(java.lang.String). It is warned that when the request is dispatched from the servlet resides in a different web application by
RequestDispatcher, the object set by this method may not be correctly retrieved in
the caller servlet.
Parameters:
name - a String specifying the name of
the attributeo - the Object to be stored
removeAttribute
void removeAttribute(java.lang.String name)
Removes an attribute from this request. This
method is not generally needed as attributes only persist as long as the
request is being handled.
Attribute
names should follow the same conventions as package names. Names beginning with
java.*, javax.*, and com.sun.*, are reserved for use by Sun Microsystems.
Parameters:
name - a String specifying the name of
the attribute to remove
getLocale
java.util.Locale getLocale()
Returns the preferred
Locale that the client will
accept content in, based on the Accept-Language header. If the client request
doesn't provide an Accept-Language header, this method returns the default
locale for the server.
Returns:
the preferred
Locale for the client
getLocales
java.util.Enumeration getLocales()
Returns an
Enumeration of Locale objects indicating, in decreasing order starting with the
preferred locale, the locales that are acceptable to the client based on the
Accept-Language header. If the client request doesn't provide an
Accept-Language header, this method returns an Enumeration containing one Locale, the default locale for
the server.
Returns:
an
Enumeration of preferred Locale objects for the client
isSecure
boolean isSecure()
Returns a boolean indicating whether this request
was made using a secure channel, such as HTTPS.
Returns:
a boolean indicating if the request was made
using a secure channel
getRequestDispatcher
RequestDispatcher getRequestDispatcher(java.lang.String path)
Returns a
RequestDispatcher object that acts as a wrapper for the
resource located at the given path. ARequestDispatcher object can be used to
forward a request to the resource or to include the resource in a response. The
resource can be dynamic or static.
The
pathname specified may be relative, although it cannot extend outside the
current servlet context. If the path begins with a "/" it is
interpreted as relative to the current context root. This method returns
null if the servlet container cannot return a RequestDispatcher.
The
difference between this method and
ServletContext.getRequestDispatcher(java.lang.String) is that this method can take a relative
path.
Parameters:
path - a String specifying the pathname
to the resource. If it is relative, it must be relative against the current
servlet.
Returns:
a
RequestDispatcher object that acts as a wrapper for the resource at the specified
path, or null if the servlet container cannot return a RequestDispatcher
See Also:
getRealPath
java.lang.String getRealPath(java.lang.String path)
Deprecated. As of Version 2.1 of the Java
Servlet API, use
ServletContext.getRealPath(java.lang.String)instead.
getRemotePort
int getRemotePort()
Returns the Internet Protocol (IP) source port of
the client or last proxy that sent the request.
Returns:
an integer specifying the port number
Since:
2.4
getLocalName
java.lang.String getLocalName()
Returns the host name of the Internet Protocol
(IP) interface on which the request was received.
Returns:
a
String containing the host name of the IP on which the request was
received.
Since:
2.4
getLocalAddr
java.lang.String getLocalAddr()
Returns the Internet Protocol (IP) address of the
interface on which the request was received.
Returns:
a
String containing the IP address on which the request was received.
Since:
2.4
getLocalPort
int getLocalPort()
Returns the Internet Protocol (IP) port number of
the interface on which the request was received.
Returns:
an integer specifying the port number
Since:
2.4
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