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Class WebSite.Servlet.Response

java.lang.Object
   |
   +----WebSite.Servlet.Response

public final class Response

extends Object

The Response class implements the WebSite Servlet response information and methods. It is a purely static class and cannot be instantiated.

The standard line terminator for HTTP (and other Internet protocols) is CR-LF. The println methods here generate these line endings. This class implements most of the methods of the PrintStream class, but with proper line terminators and better error detection. The output is normally spooled. This is the preferred mode of operation, as described in the documentation for Client.unspool(), which may be called to defeat the spooling. Unspooling the output is useful when you need a "hot" connection to the browser for things like server-push. When running in spooled mode, output is normally eligible to be sent through WebSite's post-processing chain. This means that servlet output may contain things like server-side include tags. You must set the content-type to that which is handled by the post-processor you want to handle your output. For example, to have your servlet output run through the server-side include engine, set your content type to wwwserver/html-ssi. You may defeat this feature (and realize a small performance gain) by calling Response.usePostProc(false).

Response cookie support provides the functionality described in the Netscape Cookie Specification and the new RFC 2109 State Management cookies.

See Also:

Client, Cookie, Form, Request, Server, Session

addExtraHeader(String, String)

Adds an extra meta-information header to the response.

containsExtraHeader(String)

Returns true if the response contains the named extra header.

endErrorResponse()

Finish off an HTTP "500 Server Error" response that was started with startErrorResponse.

extraHeaderCount()

Returns the number of extra headers in the response.

extraHeaderNames()

Returns an Enumeration of the extra header names in the response.

getCookies()

Returns a Vector of Cookie objects representing the cookies that have been set in the response.

getExtraHeader(String)

Gets the value of the named response extra header, or null if it is not present.

noOp()

Sends a "no-op" (204) to the client.

print(boolean)

Prints a boolean.

print(char)

Prints a character.

print(char[])

Prints an array of characters.

print(double)

Prints a double.

print(float)

Prints a float.

print(int)

Prints an integer.

print(long)

Prints a long.

print(Object)

Prints an object.

print(String)

Prints a string

print(StringBuffer)

Prints a string buffer.

println()

Prints a line terminator

println(boolean)

Prints a boolean followed by a line terminator.

println(char)

Prints a character followed by a line terminator.

println(char[])

Prints an array of characters followed by a line terminator.

println(double)

Prints a double followed by a line terminator.

println(float)

Prints a float followed by a line terminator.

println(int)

Prints an integer followed by a line terminator.

println(long)

Prints a long followed by a line terminator.

println(Object)

Prints an object followed by a line terminator.

println(String)

Prints a string followed by a line terminator.

println(StringBuffer)

Prints a string buffer followed by a line terminator.

redirect(String)

Sends a redirection response (302) to the client, causing it to immediately fetch the target URL.

sendHeaders()

Immediately sends the HTTP headers to the client.

setContentType(String)

Sets the media content type for the response body.

setCookie(Cookie)

Sets a response cookie using a given Cookie object.

setCookie(String, String)

Sets a response cookie with default attributes and the given name and string value.

setStatus(String)

Sets the HTTP status code and reason phrase for the response.

startErrorResponse()

Start an HTTP "500 server error" response.

unspool()

Unspool (unbuffer) the output.

usePostProc(boolean)

Enable or disable server post-processing on servlet output.

write(byte[])

Writes an array of bytes

write(byte[], int, int)

Writes a sub-array of bytes

write(int)

Writes a byte of data

 public static native void usePostProc(boolean enabled) throws IOException

Enable or disable server post-processing on servlet output. Default is to pass the servlet output through any configured post-processor(s). If you disable it, you cannot use WebSite Pro features such as server-side includes and the automatic S-HTTP anchor fixup. If you are certain you will not need these services for your servlet output, you can disable post-processing to eliminate the extra CPU and disk utilization needed to set up for post-processing. Post-processing is disabled if you unspool the output.

Parameters:

enabled - true to enable post-processing, false to disable it.

Throws: IOException

Thrown if you attempt to change this setting after using any of the methods that send content to the client, or after unspooling the output.

See Also:

unspool

 public static native void unspool() throws IOException

Unspool (unbuffer) the output. This causes response data to go directly to the TCP socket in whatever sized bits you write. All HTTP headers are automatically transmitted on the first write to the output. Post processors are disabled. You must unbuffer the output before writing anything. You are responsible for setting a correct content length a priori, before writing anything. If you do not know how much data you will be sending, you must disable keep-alive.

This feature is mainly useful for server-push applications. Unbuffering will not improve performance in general. The small execution speed increase is easily offset by the inefficiencies in transmitting small bits of data over the net to the client. WebSite's memory-mapped buffering maximizes network packet size and transmits all response packets as closely spaced in time as possible. This reduces the probably that packets will take different routes through the net and thereby suffer reassembly delays.

Throws: IOException

Thrown if you attempt to change this setting after using any of the methods that send content to the client.

 public static void setCookie(String name,
                              String value) throws IOException

Sets a response cookie with default attributes and the given name and string value. For complete control over the cookie attributes, use the form of setCookie() that takes the Cookie object. The cookie will be compatible with both Netscape or RFC 2109 as it will consist only of the NAME=VALUE pair.

Parameters:

name - The name of the cookie

value - The value of the cookie

Throws: IOException

Thrown if you attempt to set a cookie after using any of the methods that send content to the client.

 public static void setCookie(Cookie ck) throws IOException

Sets a response cookie using a given Cookie object.

Parameters:

ck - The Cookie object

Throws: IOException

Thrown if you attempt to set a cookie after using any of the methods that send content to the client.

See Also:

Cookie

 public static native Vector getCookies()

Returns a Vector of Cookie objects representing the cookies that have been set in the response.

 public static boolean containsExtraHeader(String name)

Returns true if the response contains the named extra header.

Parameters:

name - The name (label) of the extra header

 public static String getExtraHeader(String name)

Gets the value of the named response extra header, or null if it is not present.

Parameters:

name - The name (label) of the extra header

 public static int extraHeaderCount()

Returns the number of extra headers in the response.

 public static Enumeration extraHeaderNames()

Returns an Enumeration of the extra header names in the response. The Enumeration returns String objects that contain the header name or label of a response extra header. Note that response extra headers may be present even if you do not set any yourself.

 public static native void setContentType(String ct) throws IOException

Sets the media content type for the response body. The default is text/html, used for HTML responses. Setting this to an empty string or null will supress the Content-Type header in the response. The call to this method must occur before any content is written/printed.

Parameters:

ct - the media content type, for example text/html

Throws: IOException

Thrown if you attempt to set the content type after using any of the methods that send content to the client.

 public static native void setStatus(String st) throws IOException

Sets the HTTP status code and reason phrase for the response. The default is "200 OK". Allows construction of any HTTP response. The call to this method must occur before any content is written/printed. Also note that some HTTP messages do not normally carry any content.

Parameters:

st - the HTTP status, for example 400 Bad Request

Throws: IOException

Thrown if you attempt to set the status after using any of the methods that send content to the client.

 public static native void redirect(String uri) throws IOException

Sends a redirection response (302) to the client, causing it to immediately fetch the target URL. The call to this method must occur before any content is written/printed. Any further calls to Response methods will fail after calling this.

This method is not supported for unspooled output. To send a redirection when unspooled, you must set the 302 status and other headers yourself, then send the headers and any content you may want to be displayed by brain-dead browsers that don't automatically redirect on a 302.

Parameters:

uri - the target URL for the client

Throws: IOException

Thrown if you attempt to redirect after using any of the methods that send content to the client, or if the output is unspooled.

 public static native void noOp() throws IOException

Sends a "no-op" (204) to the client. Normally a browser does nothing in response, however some Microsoft browsers incorrectly display an error alert in response. The call to this method must occur before any content is written/printed. Any further calls to Response methods will fail after calling this.

This method is not supported for unspooled output. To send a no-op when unspooled, you must set the 204 status and other headers yourself, then send the headers.

Throws: IOException

Thrown if you attempt to noOp after using any of the methods that send content to the client, or if the output is unspooled.

 public static native void addExtraHeader(String name,
                                          String value) throws IOException

Adds an extra meta-information header to the response. The call to this method must occur before any content is written/printed.

Example:

...addExtraHeader("X-Extra-Header", "meta info");

Parameters:

name - the extra header label (without the ':')

value - the extra header value

Throws: IOException

Thrown if you attempt to add an extra header after using any of the methods that send content to the client.

 public static void sendHeaders() throws IOException

Immediately sends the HTTP headers to the client. This method is usable only if the output has been unspooled. It has the same effect as writing content, therefore all Response methods that affect the headers will throw IOExceptions if called after sending the headers. The header data is immediately transmitted to the network.

You must perform all operations that affect the headers and the HTTP status before calling this method. This includes cookie and extra header operations, and setting the HTTP status.

NOTE: This method is called implicitly (on unspooled output) if any of the write/print methods are called without having first called sendHeaders().

Throws: IOException

Thrown if you attempt to send headers when the output is spooled, or after using any of the methods that send content to the client.

See Also:

unspool

 public static void startErrorResponse() throws IOException

Start an HTTP "500 server error" response. This method clears any data that may have been written to the output and replaces it with the start of an HTTP "500 Server Error" response.

Throws: IOException

Thrown if there is a problem writing to the client

See Also:

endErrorResponse

 public static void endErrorResponse() throws IOException

Finish off an HTTP "500 Server Error" response that was started with startErrorResponse.

Throws: IOException

Thrown if there is a problem writing to the client

See Also:

startErrorResponse

 public static void write(int b) throws IOException

Writes a byte of data

Parameters:

b - the byte to be written

Throws: IOException

Thrown if there is a problem writing to the client

 public static void write(byte b[]) throws IOException

Writes an array of bytes

Parameters:

b - the data to be written

Throws: IOException

Thrown if there is a problem writing to the client

 public static void write(byte b[],
                          int off,
                          int len) throws IOException

Writes a sub-array of bytes

Parameters:

b - the data to be written

off - the start offset in the data

len - the number of bytes to be written

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(String s) throws IOException

Prints a string

Parameters:

s - the string (writes "null" if null)

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(char s[]) throws IOException

Prints an array of characters.

Parameters:

s - the array of chars (writes 'n' 'u' 'l' 'l' '\0' if null)

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(StringBuffer sb) throws IOException

Prints a string buffer.

Parameters:

sb - the StringBuffer object (writes "null" if null)

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(char c) throws IOException

Prints a character.

Parameters:

c - the character to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(int i) throws IOException

Prints an integer.

Parameters:

i - the integer to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(long l) throws IOException

Prints a long.

Parameters:

l - the long to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(float f) throws IOException

Prints a float.

Parameters:

f - the float to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(double d) throws IOException

Prints a double.

Parameters:

d - the double to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(boolean b) throws IOException

Prints a boolean.

Parameters:

b - the boolean to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void print(Object o) throws IOException

Prints an object.

Parameters:

o - the object to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(String s) throws IOException

Prints a string followed by a line terminator.

Parameters:

s - the string to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(StringBuffer sb) throws IOException

Prints a string buffer followed by a line terminator.

Parameters:

sb - the string buffer

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println() throws IOException

Prints a line terminator

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(char s[]) throws IOException

Prints an array of characters followed by a line terminator.

Parameters:

s - the array of characters to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(char c) throws IOException

Prints a character followed by a line terminator.

Parameters:

c - the character to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(int i) throws IOException

Prints an integer followed by a line terminator.

Parameters:

i - the integer to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(long l) throws IOException

Prints a long followed by a line terminator.

Parameters:

l - the long to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(float f) throws IOException

Prints a float followed by a line terminator.

Parameters:

f - the float to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(double d) throws IOException

Prints a double followed by a line terminator.

Parameters:

d - the double to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(boolean b) throws IOException

Prints a boolean followed by a line terminator.

Parameters:

b - the boolean to be printed

Throws: IOException

Thrown if there is a problem writing to the client

 public static void println(Object obj) throws IOException

Prints an object followed by a line terminator.

Parameters:

obj - the object to be printed

Throws: IOException

Thrown if there is a problem writing to the client

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