javax.servlet

## Interface ServletRequest

All Known Subinterfaces:
  HttpServletRequest

All Known Implementing Classes:
  HttpServletRequestWrapper, ServletRequestWrapper

    public interface ServletRequest

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`.

Author:
  Various
See Also:
  `HttpServletRequest`

### Method Summary

Methods
`AsyncContext` `getAsyncContext()`
`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<java.lang.String>` `getAttributeNames()` Returns an `Enumeration` containing the names of the attributes available to this request.
`java.lang.String` `getCharacterEncoding()` Returns the name of the character encoding used in the body of this request.
`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.
`DispatcherType` `getDispatcherType()`
`ServletInputStream` `getInputStream()` Retrieves the body of the request as binary data using a `ServletInputStream`.
`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<java.util.Locale>` `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.lang.String,java.lang.String[]>` `getParameterMap()` Returns a java.util.Map of the parameters of this request.
`java.util.Enumeration<java.lang.String>` `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 form protocol/majorVersion.minorVersion, for example, HTTP/1.1.
`java.io.BufferedReader` `getReader()` Retrieves the body of the request as character data using a `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.
`RequestDispatcher` `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`, or `ftp`.
`java.lang.String` `getServerName()` Returns the host name of the server to which the request was sent.
`int` `getServerPort()` Returns the port number to which the request was sent.
`ServletContext` `getServletContext()`
`boolean` `isAsyncStarted()`
`boolean` `isAsyncSupported()`
`boolean` `isSecure()` Returns a boolean indicating whether this request was made using a secure channel, such as HTTPS.
`void` `removeAttribute(java.lang.String name)` Removes an attribute from this request.
`void` `setAttribute(java.lang.String name, java.lang.Object o)` Stores an attribute in this request.
`void` `setCharacterEncoding(java.lang.String env)` Overrides the name of the character encoding used in the body of this request.
`AsyncContext` `startAsync()`
`AsyncContext` `startAsync(ServletRequest servletRequest, ServletResponse servletResponse)`

### Method Detail

#### 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 using `setAttribute(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<java.lang.String> 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().

Parameters:
  `env` - a `String` containing the name of the character encoding.
Throws:
  `java.io.UnsupportedEncodingException` - if this is not a valid encoding

#### 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 request
  `java.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:
  `getParameterValues(java.lang.String)`

#### getParameterNames

    java.util.Enumeration<java.lang.String> 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 empty `Enumeration` 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:
  `getParameter(java.lang.String)`

#### getParameterMap

    java.util.Map<java.lang.String,java.lang.String[]> 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 `Host` header 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:
  `java.io.UnsupportedEncodingException` - if the character set encoding used is not supported and the text cannot be decoded
  `java.lang.IllegalStateException` - if `getInputStream()` method has been called on this request
  `java.io.IOException` - if an input or output exception occurred
See Also:
  `getInputStream()`

#### 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 `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 attribute
  `o` - 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<java.util.Locale> 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. A `RequestDispatcher` 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:
  `RequestDispatcher`, `ServletContext.getRequestDispatcher(java.lang.String)`

#### 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

#### getServletContext

    ServletContext getServletContext()

Returns:
  TODO
Since:
  Servlet 3.0 TODO SERVLET3 - Add comments

#### startAsync

    AsyncContext startAsync()

Returns:
  TODO
Throws:
  `java.lang.IllegalStateException` - If async is not supported for this request
Since:
  Servlet 3.0 TODO SERVLET3 - Add comments

#### startAsync

    AsyncContext startAsync(ServletRequest servletRequest,
                          ServletResponse servletResponse)

Parameters:
  `servletRequest` -
  `servletResponse` -
Returns:
  TODO
Throws:
  `java.lang.IllegalStateException`
Since:
  Servlet 3.0 TODO SERVLET3 - Add comments

#### isAsyncStarted

    boolean isAsyncStarted()

Returns:
  TODO
Since:
  Servlet 3.0 TODO SERVLET3 - Add comments

#### isAsyncSupported

    boolean isAsyncSupported()

Returns:
  TODO
Since:
  Servlet 3.0 TODO SERVLET3 - Add comments

#### getAsyncContext

    AsyncContext getAsyncContext()

Returns:
  TODO
Throws:
  `java.lang.IllegalStateException`
Since:
  Servlet 3.0 TODO SERVLET3 - Add comments

#### getDispatcherType

    DispatcherType getDispatcherType()

Returns:
  TODO
Since:
  Servlet 3.0 TODO SERVLET3 - Add comments