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ISBN: 0735711119

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HttpServletRequest and HttpServletResponse

Communication with client connections happens through the HttpServletRequest and HttpServletResponse object. These are abstractions of the literal request stream received from and sent to the client. Each of these objects adds higher-level, HTTP-specific methods to ease working with requests and responses.

Table 12.3 is a list of the methods within the HttpServletRequest object. A great majority of the methods are bean property accessors, which means that you can reference them with Jython's automatic bean properties. This may not be as great of an advantage here as it is for GUI programming because there is no opportunity to leverage this facility in method keyword arguments. Table 12.3 shows the methods and bean property names from the HttpServletRequest object.

Table 12.3 HttpServletRequest Methods and Properties

Method and Property	Description
Method:`getAuthType()`Property name: `AuthType`	Returns a string (`PyString`) describing the name of the authentication type. The value is `None` if the user is notauthenticated.
Method:`getContextPath()`Property name: `contextPath`	Returns a string (`PyString)` describing the path information that identifies the context requested.
Method: `getCookies()`Property name: `cookies()`	Returns all cookies sent with the client's request as an array of `javax.servlet.http.Cookie` objects.
Method: `getDateHeader(name)`	Retrieves the value of the specified header as a long type.
Method: `getHeader(name)`	Returns the value of the specified header as string (`PyString`).
Method:`getHeaderNames()`Property name: `headerNames`	Returns all the header names contained within the request as an Enumeration.
Method: `getHeaders(name)`	Returns all the values of the specified header name as an Enumeration.
Method: `getIntHeader(name)`	Retrieves the specified header value as a Java `int`, which Jython converts to a `PyInteger`.
Method: `getMethod()` Property name: `method`	Returns the type of request made a string.
Method: `getPathInfo()`Property name: `pathInfo`	All extra path information sent by the client.
Method: `getPathTranslated()`Property name: `pathTranslated`	Returns the real path derived from extra path information in the client's request.
Method: `getQueryString()` Property name: `queryString`	Returns the query string from the client's request (the string after the path).
Method: `getRemoteUser()` Property name: `remoteUser`	Returns the login name of the client. None if the client is not authenticated.
Method: `getRequestedSessionId()` Property name: `requestedSessionId`	Returns the clients session ID.
Method: `getRequestURI()` Property name: `requestURI`	Returns that segment of the between the protocol name and the query string.
Method: `getServletPath()` Property name: `servletPath`	Returns the portion of the URL that designates the current Servlet.
Method: `getSession()` Property name: `session`	Returns the current session, or creates on if needed. A session is an instance of `javax.servlet.http.HttpSession`.
Method: `getSession(create)`	Returns the current session if one exists. If not, a new session is created if the create value is true.
Method: `getUserPrincipal()` Property name: `userPrincipal`	Returns a `java.security.Principal` `o`bject with the current authentication information `userPrincipal`
Method: `isRequestedSessionIdFromCookie()`	Returns `1` or `0` depending on whether the current session ID was from a cookie.
Method: `isRequestedSessionIdFromURL()`	Returns `1` or `0` depending on whether the current session ID was from the requested URL string.
Method: `isRequestedSessionIdValid()`	Returns `1` or `0` depending on whether the requested session ID is still valid.
Method: `isUserInRole(role)`	Returns `1` or `0` indicating whether the user is listed in the specified role.

The HttpServletResponse object is used to send the mime-encoded stream back to the client. HttpServletResponse defines additional HTTP-specific methods that do not exist in a generic ServletResponse object. The methods within the HttpServletResponse object appear in Table 12.4. Whereas Jython adds numerous automatic bean properties to the HttpServletRequest object, the HttpServletResponse object only has one: status.

Table 12.4 HttpServletResponse Methods and Properties

Method and Property	Description
`addCookie(cookie)`	Add a cookie to the response.
`addDateHeader(headerName, date)`	Adds a header name with a date (long) value.
`addHeader(headerName, value)`	Adds a header name and value.
`addIntHeader(headerName, value)`	Adds a header name with an integer value.
`containsHeader(headerName)`	Returns a `1` or `0` depending whether the specified header.
`encodeRedirectUrl(url)`	Encodes a URL for the `sendRedirect` method. For version 2.1 and greater, use `encodeRedirectURL` instead.
`encodeRedirectURL(url)`	Encodes a URL for the `sendRedirect` method.
`encodeURL(url)`	Encodes a URL by including the session ID in it.
`sendError(sc)`	Sends an error using the status code.
`sendError(sc, msg)`	Sends an error using the specified status code and message.
`sendRedirect(location)`	Sends a temporary redirect to the specified location.
`setDateHeader(headerName, date)`	Sets a header name to the specified date (long) value.
`setHeader(headerName, value)`	Sets a header name to the specified value.
`setIntHeader(headerName, value)`	Sets a header name to the specified integer value.
`setStatus(statusCode) status`	Sets the response status code.

The HttpServletResponse class also contains fields that correspond to the standard HTTP response codes. You can use these with sendError(int) and setStatus(int). Table 12.5 lists the number and error code for these status codes.

Table 12.5 HttpServletResponse Status CodesError

Code	Status
`100`	`SC_CONTINUE`
`101`	`SC_SWITCHING_PROTOCOLS`
`200`	`SC_OK`
`201`	`SC_CONTINUE`
`202`	`SC_ACCEPTED`
`203`	`SC_NON_AUTHORITATIVE_INFORMATION`
`204`	`SC_NO_CONTENT`
`205`	`SC_RESET_CONTENT`
`206`	`SC_PARTIAL_CONTENT`
`300`	`SC_MULTIPLE_CHOICES`
`301`	`SC_MOVED_PERMANENTLY`
`302`	`SC_MOVED_TEMPORARILY`
`303`	`SC_SEE_OTHER`
`304`	`SC_NOT_MODIFIED`
`305`	`SC_USE_PROXY`
`400`	`SC_BAD_REQUEST`
`401`	`SC_UNAUTHORIZED`
`402`	`SC_PAYMENT_REQUIRED`
`403`	`SC_FORBIDDEN`
`404`	`SC_NOT_FOUND`
`405`	`SC_METHOD_NOT_ALLOWED`
`406`	`SC_NOT_ACCEPTABLE`
`407`	`SC_PROXY_AUTHENTICATION_REQUIRED`
`408`	`SC_REQUEST_TIMEOUT`
`409`	`SC_CONFLICT`
`410`	`SC_GONE`
`411`	`SC_LENGTH_REQUIRED`
`412`	`SC_PRECONDITION_FAILED`
`413`	`SC_REQUEST_ENTITY_TOO_LARGE`
`414`	`SC_REQUEST_URI_TOO_LONG`
`415`	`SC_UNSUPPORTED_MEDIA_TYPE`
`500`	`SC_INTERNAL_SERVER_ERROR`
`501`	`SC_NOT_IMPLEMENTED`
`502`	`SC_BAD_GATEWAY`
`503`	`SC_SERVICE_UNAVAILABLE`
`504`	`SC_GATEWAY_TIMEOUT`
`505`	`SC_HTTP_VERSION_NOT_SUPPORTED`

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