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Interface ServletRequest

All Known Subinterfaces:

HttpServletRequest

All Known Implementing Classes:

ServletRequestWrapper

public interfaceServletRequest

Defines an object to provide client request information to a servlet. The servlet container creates aServletRequest object and passes it as an argument to the servlet'sservice method.

AServletRequest object provides data including parameter name and values, attributes, and an input stream. Interfaces that extendServletRequest can provide additional protocol-specific data (for example, HTTP data is provided byHttpServletRequest.

See Also:

HttpServletRequest

getAttribute

public java.lang.ObjectgetAttribute(java.lang.String name)

Returns the value of the named attribute as anObject, ornull 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 attributejavax.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 aRequestDispatcher call.

Attribute names should follow the same conventions as package names. This specification reserves names matchingjava.*,javax.*, andsun.*.

Parameters:

name - aString specifying the name of the attribute

Returns:

anObject containing the value of the attribute, ornull ifthe attribute does not exist

getAttributeNames

public java.util.EnumerationgetAttributeNames()

Returns anEnumeration containing the names of the attributes available to this request. This method returns an emptyEnumeration if the request has no attributes available to it.

Returns:

anEnumeration of strings containing the names of the request's attributes

getCharacterEncoding

public java.lang.StringgetCharacterEncoding()

Returns the name of the character encoding used in the body of this request. This method returnsnull if the request does not specify a character encoding

Returns:

aString containing the name of the chararacter encoding, ornullif the request does not specify a character encoding

setCharacterEncoding

public voidsetCharacterEncoding(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().

Parameters:

a -String containing the name of the chararacter encoding.

Throws:

java.io.UnsupportedEncodingException - if this is not a valid encoding

getContentLength

public intgetContentLength()

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

public java.lang.StringgetContentType()

Returns the MIME type of the body of the request, ornull if the type is not known. For HTTP servlets, same as the value of the CGI variable CONTENT_TYPE.

Returns:

aString containing the name of the MIME type of the request, or null if the type is not known

getInputStream

publicServletInputStreamgetInputStream()                                  throws java.io.IOException

Retrieves the body of the request as binary data using aServletInputStream. Either this method orgetReader() may be called to read the body, not both.

Returns:

aServletInputStream object containing the body of the request

Throws:

java.lang.IllegalStateException - if thegetReader() method has already been called for this request

java.io.IOException - if an input or output exception occurred

getParameter

public java.lang.StringgetParameter(java.lang.String name)

Returns the value of a request parameter as aString, ornull 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, usegetParameterValues(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 bygetParameterValues.

If the parameter data was sent in the request body, such as occurs with an HTTP POST request, then reading the body directly viagetInputStream() orgetReader() can interfere with the execution of this method.

Parameters:

name - aString specifying the name of the parameter

Returns:

aString representing the single value of the parameter

See Also:

getParameterValues(java.lang.String)

getParameterNames

public java.util.EnumerationgetParameterNames()

Returns anEnumeration ofString objects containing the names of the parameters contained in this request. If the request has no parameters, the method returns an emptyEnumeration.

Returns:

anEnumeration ofStringobjects, eachString containing the name of a request parameter; or an emptyEnumeration if therequest has no parameters

getParameterValues

public java.lang.String[]getParameterValues(java.lang.String name)

Returns an array ofString objects containing all of the values the given request parameter has, ornull if the parameter does not exist.

If the parameter has a single value, the array has a length of 1.

Parameters:

name - aString containing the name of the parameter whose value is requested

Returns:

an array ofString objects containing the parameter's values

See Also:

getParameter(java.lang.String)

getParameterMap

public java.util.MapgetParameterMap()

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

public java.lang.StringgetProtocol()

Returns the name and version of the protocol the request uses in the formprotocol/majorVersion.minorVersion, for example, HTTP/1.1. For HTTP servlets, the value returned is the same as the value of the CGI variableSERVER_PROTOCOL.

Returns:

aString containing the protocol name and version number

getScheme

public java.lang.StringgetScheme()

Returns the name of the scheme used to make this request, for example,http,https, orftp. Different schemes have different rules for constructing URLs, as noted in RFC 1738.

Returns:

aString containing the name of the scheme used to make this request

getServerName

public java.lang.StringgetServerName()

Returns the host name of the server that received the request. For HTTP servlets, same as the value of the CGI variableSERVER_NAME.

Returns:

aString containing the name of the server to which the request was sent

getServerPort

public intgetServerPort()

Returns the port number on which this request was received. For HTTP servlets, same as the value of the CGI variableSERVER_PORT.

Returns:

an integer specifying the port number

getReader

public java.io.BufferedReadergetReader()                                 throws java.io.IOException

Retrieves the body of the request as character data using aBufferedReader. The reader translates the character data according to the character encoding used on the body. Either this method orgetInputStream() may be called to read the body, not both.

Returns:

aBufferedReadercontaining the body of the request

Throws:

java.io.UnsupportedEncodingException - if the character set encoding used is not supported and the text cannot be decoded

java.lang.IllegalStateException - ifgetInputStream() method has been called on this request

java.io.IOException - if an input or output exception occurred

See Also:

getInputStream()

getRemoteAddr

public java.lang.StringgetRemoteAddr()

Returns the Internet Protocol (IP) address of the client that sent the request. For HTTP servlets, same as the value of the CGI variableREMOTE_ADDR.

Returns:

aString containing the IP address of the client that sent the request

getRemoteHost

public java.lang.StringgetRemoteHost()

Returns the fully qualified name of the client 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 variableREMOTE_HOST.

Returns:

aString containing the fully qualified name of the client

setAttribute

public voidsetAttribute(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 withRequestDispatcher.

Attribute names should follow the same conventions as package names. Names beginning withjava.*,javax.*, andcom.sun.*, are reserved for use by Sun Microsystems.
If the value passed in is null, the effect is the same as callingremoveAttribute(java.lang.String).

Parameters:

name - aString specifying the name of the attribute

o - theObject to be stored

removeAttribute

public voidremoveAttribute(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 withjava.*,javax.*, andcom.sun.*, are reserved for use by Sun Microsystems.

Parameters:

name - aString specifying the name of the attribute to remove

getLocale

public java.util.LocalegetLocale()

Returns the preferredLocale 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 preferredLocale for the client

getLocales

public java.util.EnumerationgetLocales()

Returns anEnumeration ofLocale 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 anEnumeration containing oneLocale, the default locale for the server.

Returns:

anEnumeration of preferredLocale objects for the client

isSecure

public booleanisSecure()

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

publicRequestDispatchergetRequestDispatcher(java.lang.String path)

Returns aRequestDispatcher 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 returnsnull if the servlet container cannot return aRequestDispatcher.

The difference between this method andServletContext.getRequestDispatcher(java.lang.String) is that this method can take a relative path.

Parameters:

path - aString specifying the pathname to the resource

Returns:

aRequestDispatcher object that acts as a wrapper for the resource at the specified path

See Also:

RequestDispatcher,ServletContext.getRequestDispatcher(java.lang.String)

getRealPath

public java.lang.StringgetRealPath(java.lang.String path)

Deprecated. As of Version 2.1 of the Java Servlet API, useServletContext.getRealPath(java.lang.String) instead.