org.simpleframework.http
Class ResponseWrapper

java.lang.Object
  org.simpleframework.http.ResponseWrapper

All Implemented Interfaces:

Response, ResponseHeader, StatusLine

public class ResponseWrapper
extends Object
implements Response

The ResponseWrapper object is used so that the original Response object can be wrapped in a filtering proxy object. This allows a container to interact with an implementation of this with overridden methods providing specific functionality. the Response object in a concurrent environment.

    public void handle(Request req, Response resp) {
       handler.handle(req, new ZipResponse(resp));
    }

 

The above is an example of how the ResponseWrapper can be used to provide extra functionality to a Response in a transparent manner. Such an implementation could apply a Content-Encoding header and compress the response for performance over a slow network. Filtering can be applied with the use of layered Container objects.

Author:

Niall Gallagher

See Also:

Container

Field Summary

protected Response

response This is the response instance that is being wrapped.

Constructor Summary

ResponseWrapper(Response response)
Constructor for ResponseWrapper object.

Method Summary

void	addDate(String name, long date) This is used as a convenience method for adding a header that needs to be parsed into a HTTPdate string.
void	addInteger(String name, int value) This can be used to add a HTTP message header to this object.
void	addValue(String name, String value) This can be used to add a HTTP message header to this object.
void	close() This is used to close the connection and commit the request.
void	commit() This is used to write the headers that where given to the Response.
WritableByteChannel	getByteChannel() Used to write a message body with the Response.
WritableByteChannel	getByteChannel(int size) Used to write a message body with the Response.
int	getCode() This represents the status code of the HTTP response.
long	getContentLength() This is a convenience method that can be used to determine the length of the message body.
ContentType	getContentType() This is a convenience method that can be used to determine the content type of the message body.
Cookie	getCookie(String name) This returns the Cookie object stored under the specified name.
List<Cookie>	getCookies() This returns all Cookie objects stored under the specified name.
long	getDate(String name) This can be used to get the value of the first message header that has the specified name.
String	getDescription() This can be used to retrieve the text of a HTTP status line.
CharSequence	getHeader() This method returns a CharSequence holding the header created for the request.
int	getInteger(String name) This can be used to get the value of the first message header that has the specified name.
int	getMajor() This can be used to get the major number from a HTTP version.
int	getMinor() This can be used to get the minor number from a HTTP version.
List<String>	getNames() This is used to acquire the names of the of the headers that have been set in the response.
OutputStream	getOutputStream() Used to write a message body with the Response.
OutputStream	getOutputStream(int size) Used to write a message body with the Response.
PrintStream	getPrintStream() This method is provided for convenience so that the HTTP content can be written using the print methods provided by the PrintStream.
PrintStream	getPrintStream(int size) This method is provided for convenience so that the HTTP content can be written using the print methods provided by the PrintStream.
long	getResponseTime() This represents the time at which the response has fully written.
Status	getStatus() This is used to acquire the status from the response.
String	getTransferEncoding() This is a convenience method that can be used to determine the content type of the message body.
String	getValue(String name) This can be used to get the value of the first message header that has the specified name.
String	getValue(String name, int index) This can be used to get the value of the first message header that has the specified name.
List<String>	getValues(String name) This can be used to get the values of HTTP message headers that have the specified name.
boolean	isCommitted() This can be used to determine whether the Response has been committed.
boolean	isKeepAlive() This is used to determine if the HTTP response message is a keep alive message or if the underlying socket was closed.
void	reset() This can be used to determine whether the Response has been committed.
void	setCode(int code) This method allows the status for the response to be changed.
void	setContentLength(long length) This should be used when the size of the message body is known.
void	setContentType(String type) This is used to set the content type for the response.
Cookie	setCookie(Cookie cookie) The setCookie method is used to set a cookie value with the cookie name.
Cookie	setCookie(String name, String value) The setCookie method is used to set a cookie value with the cookie name.
void	setDate(String name, long date) This is used as a convenience method for adding a header that needs to be parsed into a HTTP date string.
void	setDescription(String text) This is used to set the text of the HTTP status line.
void	setInteger(String name, int value) This can be used to set a HTTP message header to this object.
void	setLong(String name, long value) This can be used to set a HTTP message header to this object.
void	setMajor(int major) This can be used to set the major number from a HTTP version.
void	setMinor(int minor) This can be used to get the minor number from a HTTP version.
void	setStatus(Status status) This is used to set the status code and description for this response.
void	setValue(String name, String value) This can be used to set a HTTP message header to this object.
String	toString() This method returns a string representing the header that was generated for this header.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

response

protected Response response

This is the response instance that is being wrapped.

Constructor Detail

ResponseWrapper

public ResponseWrapper(Response response)

Constructor for ResponseWrapper object. This allows the original Response object to be wrapped so that adjustments to the behavior of a request object handed to the container can be provided by a subclass implementation.

Parameters:

response - the response object that is being wrapped

Method Detail

getCode

public int getCode()

This represents the status code of the HTTP response. The response code represents the type of message that is being sent to the client. For a description of the codes see RFC 2616 section 10, Status Code Definitions.

Specified by:

getCode in interface StatusLine

Returns:

the status code that this HTTP response has

setCode

public void setCode(int code)

This method allows the status for the response to be changed. This MUST be reflected the the response content given to the client. For a description of the codes see RFC 2616 section 10, Status Code Definitions.

Specified by:

setCode in interface StatusLine

Parameters:

code - the new status code for the HTTP response

getDescription

public String getDescription()

This can be used to retrieve the text of a HTTP status line. This is the text description for the status code. This should match the status code specified by the RFC.

Specified by:

getDescription in interface StatusLine

Returns:

the message description of the response

setDescription

public void setDescription(String text)

This is used to set the text of the HTTP status line. This should match the status code specified by the RFC.

Specified by:

setDescription in interface StatusLine

Parameters:

text - the descriptive text message of the status

getStatus

public Status getStatus()

This is used to acquire the status from the response. The Status object returns represents the code that has been set on the response, it does not necessarily represent the description in the response.

Specified by:

getStatus in interface StatusLine

Returns:

this is the response for this status line

setStatus

public void setStatus(Status status)

This is used to set the status code and description for this response. Setting the code and description in this manner provides a much more convenient way to set the response status line details.

Specified by:

setStatus in interface StatusLine

Parameters:

status - this is the status to set on the response

getMajor

public int getMajor()

This can be used to get the major number from a HTTP version. The major version corresponds to the major type that is the 1 of a HTTP/1.0 version string.

Specified by:

getMajor in interface StatusLine

Returns:

the major version number for the request message

setMajor

public void setMajor(int major)

This can be used to set the major number from a HTTP version. The major version corresponds to the major type that is the 1 of a HTTP/1.0 version string.

Specified by:

setMajor in interface StatusLine

Parameters:

major - the major version number for the request message

getMinor

public int getMinor()

This can be used to get the minor number from a HTTP version. The minor version corresponds to the major type that is the 0 of a HTTP/1.0 version string. This is used to determine if the request message has keep alive semantics.

Specified by:

getMinor in interface StatusLine

Returns:

the minor version number for the request message

setMinor

public void setMinor(int minor)

This can be used to get the minor number from a HTTP version. The minor version corresponds to the major type that is the 0 of a HTTP/1.0 version string. This is used to determine if the request message has keep alive semantics.

Specified by:

setMinor in interface StatusLine

Parameters:

minor - the minor version number for the request message

getResponseTime

public long getResponseTime()

This represents the time at which the response has fully written. Because the response is delivered asynchronously to the client this response time does not represent the time to last byte. It simply represents the time at which the response has been fully generated and written to the output buffer or queue. This returns zero if the response has not finished.

Specified by:

getResponseTime in interface Response

Returns:

this is the time taken to complete the response

getNames

public List<String> getNames()

This is used to acquire the names of the of the headers that have been set in the response. This can be used to acquire all header values by name that have been set within the response. If no headers have been set this will return an empty list.

Specified by:

getNames in interface ResponseHeader

Returns:

a list of strings representing the set header names

addValue

public void addValue(String name,
                     String value)

This can be used to add a HTTP message header to this object. The name and value of the HTTP message header will be used to create a HTTP message header object which can be retrieved using the getValue in combination with the get methods.

Specified by:

addValue in interface ResponseHeader

Parameters:

name - the name of the HTTP message header to be added

value - the value the HTTP message header will have

addInteger

public void addInteger(String name,
                       int value)

This can be used to add a HTTP message header to this object. The name and value of the HTTP message header will be used to create a HTTP message header object which can be retrieved using the getInteger in combination with the get methods.

Specified by:

addInteger in interface ResponseHeader

Parameters:

name - the name of the HTTP message header to be added

value - the value the HTTP message header will have

addDate

public void addDate(String name,
                    long date)

This is used as a convenience method for adding a header that needs to be parsed into a HTTPdate string. This will convert the date given into a date string defined in RFC 2616 sec 3.3.1.

Specified by:

addDate in interface ResponseHeader

Parameters:

name - the name of the HTTP message header to be added

date - the value constructed as an RFC 1123 date string

setValue

public void setValue(String name,
                     String value)

This can be used to set a HTTP message header to this object. The name and value of the HTTP message header will be used to create a HTTP message header object which can be retrieved using the getValue in combination with the get methods. This will perform a remove using the issued header name before the header value is set.

Specified by:

setValue in interface ResponseHeader

Parameters:

name - the name of the HTTP message header to be added

value - the value the HTTP message header will have

setInteger

public void setInteger(String name,
                       int value)

This can be used to set a HTTP message header to this object. The name and value of the HTTP message header will be used to create a HTTP message header object which can be retrieved using the getValue in combination with the get methods. This will perform a remove using the issued header name before the header value is set.

Specified by:

setInteger in interface ResponseHeader

Parameters:

name - the name of the HTTP message header to be added

value - the value the HTTP message header will have

setLong

public void setLong(String name,
                    long value)

This can be used to set a HTTP message header to this object. The name and value of the HTTP message header will be used to create a HTTP message header object which can be retrieved using the getValue in combination with the get methods. This will perform a remove using the issued header name before the header value is set.

Specified by:

setLong in interface ResponseHeader

Parameters:

name - the name of the HTTP message header to be added

value - the value the HTTP message header will have

setDate

public void setDate(String name,
                    long date)

This is used as a convenience method for adding a header that needs to be parsed into a HTTP date string. This will convert the date given into a date string defined in RFC 2616 sec 3.3.1. This will perform a remove using the issued header name before the header value is set.

Specified by:

setDate in interface ResponseHeader

Parameters:

name - the name of the HTTP message header to be added

date - the value constructed as an RFC 1123 date string

getValue

public String getValue(String name)

This can be used to get the value of the first message header that has the specified name. This will return the full string representing the named header value. If the named header does not exist then this will return a null value.

Specified by:

getValue in interface ResponseHeader

Parameters:

name - the HTTP message header to get the value from

Returns:

this returns the value that the HTTP message header

getValue

public String getValue(String name,
                       int index)

This can be used to get the value of the first message header that has the specified name. This will return the full string representing the named header value. If the named header does not exist then this will return a null value.

Specified by:

getValue in interface ResponseHeader

Parameters:

name - the HTTP message header to get the value from

index - used if there are multiple headers present

Returns:

this returns the value that the HTTP message header

getInteger

public int getInteger(String name)

This can be used to get the value of the first message header that has the specified name. This will return the integer representing the named header value. If the named header does not exist then this will return a value of minus one, -1.

Specified by:

getInteger in interface ResponseHeader

Parameters:

name - the HTTP message header to get the value from

Returns:

this returns the value that the HTTP message header

getDate

public long getDate(String name)

This can be used to get the value of the first message header that has the specified name. This will return the long value representing the named header value. If the named header does not exist then this will return a value of minus one, -1.

Specified by:

getDate in interface ResponseHeader

Parameters:

name - the HTTP message header to get the value from

Returns:

this returns the value that the HTTP message header

getValues

public List<String> getValues(String name)

This can be used to get the values of HTTP message headers that have the specified name. This is a convenience method that will present that values as tokens extracted from the header. This has obvious performance benefits as it avoids having to deal with substring and trim calls.

The tokens returned by this method are ordered according to there HTTP quality values, or "q" values, see RFC 2616 section 3.9. This also strips out the quality parameter from tokens returned. So "image/html; q=0.9" results in "image/html". If there are no "q" values present then order is by appearance.

The result from this is either the trimmed header value, that is, the header value with no leading or trailing whitespace or an array of trimmed tokens ordered with the most preferred in the lower indexes, so index 0 is has highest preference.

Specified by:

getValues in interface ResponseHeader

Parameters:

name - the name of the headers that are to be retrieved

Returns:

ordered list of tokens extracted from the header(s)

setCookie

public Cookie setCookie(Cookie cookie)

The setCookie method is used to set a cookie value with the cookie name. This will add a cookie to the response stored under the name of the cookie, when this is committed it will be added as a Set-Cookie header to the resulting response.

Specified by:

setCookie in interface ResponseHeader

Parameters:

cookie - this is the cookie to be added to the response

Returns:

returns the cookie that has been set in the response

setCookie

public Cookie setCookie(String name,
                        String value)

The setCookie method is used to set a cookie value with the cookie name. This will add a cookie to the response stored under the name of the cookie, when this is committed it will be added as a Set-Cookie header to the resulting response. This is a convenience method that avoids cookie creation.

Specified by:

setCookie in interface ResponseHeader

Parameters:

name - this is the cookie to be added to the response

value - this is the cookie value that is to be used

Returns:

returns the cookie that has been set in the response

getCookie

public Cookie getCookie(String name)

This returns the Cookie object stored under the specified name. This is used to retrieve cookies that have been set with the setCookie methods. If the cookie does not exist under the specified name this will return null.

Specified by:

getCookie in interface ResponseHeader

Parameters:

name - this is the name of the cookie to be retrieved

Returns:

returns the cookie object send with the request

getCookies

public List<Cookie> getCookies()

This returns all Cookie objects stored under the specified name. This is used to retrieve cookies that have been set with the setCookie methods. If there are no cookies then this will return an empty list.

Specified by:

getCookies in interface ResponseHeader

Returns:

returns all the cookie objects for this response

getContentType

public ContentType getContentType()

This is a convenience method that can be used to determine the content type of the message body. This will determine whether there is a Content-Type header, if there is then this will parse that header and represent it as a typed object which will expose the various parts of the HTTP header.

Specified by:

getContentType in interface ResponseHeader

Returns:

this returns the content type value if it exists

getTransferEncoding

public String getTransferEncoding()

This is a convenience method that can be used to determine the content type of the message body. This will determine whether there is a Transfer-Encoding header, if there is then this will parse that header and return the first token in the comma separated list of values, which is the primary value.

Specified by:

getTransferEncoding in interface ResponseHeader

Returns:

this returns the transfer encoding value if it exists

getContentLength

public long getContentLength()

This is a convenience method that can be used to determine the length of the message body. This will determine if there is a Content-Length header, if it does then the length can be determined, if not then this returns -1.

Specified by:

getContentLength in interface ResponseHeader

Returns:

content length, or -1 if it cannot be determined

setContentLength

public void setContentLength(long length)

This should be used when the size of the message body is known. For performance reasons this should be used so the length of the output is known. This ensures that Persistent HTTP (PHTTP) connections can be maintained for both HTTP/1.0 and HTTP/1.1 clients. If the length of the output is not known HTTP/1.0 clients will require a connection close, which reduces performance (see RFC 2616).

This removes any previous Content-Length headers from the message header. This will then set the appropriate Content-Length header with the correct length. If a the Connection header is set with the close token then the semantics of the connection are such that the server will close it once the OutputStream.close is used.

Specified by:

setContentLength in interface Response

Parameters:

length - this is the length of the HTTP message body

setContentType

public void setContentType(String type)

This is used to set the content type for the response. Typically a response will contain a message body of some sort. This is used to conveniently set the type for that response. Setting the content type can also be done explicitly if desired.

Specified by:

setContentType in interface Response

Parameters:

type - this is the type that is to be set in the response

getHeader

public CharSequence getHeader()

This method returns a CharSequence holding the header created for the request. A character sequence is returned as it can provide a much more efficient means of representing the header data by just wrapping the the data generated.

Specified by:

getHeader in interface ResponseHeader

Returns:

this returns the characters generated for the header

getOutputStream

public OutputStream getOutputStream()
                             throws IOException

Used to write a message body with the Response. The semantics of this OutputStream will be determined by the HTTP version of the client, and whether or not the content length has been set, through the setContentLength method. If the length of the output is not known then the output is chunked for HTTP/1.1 clients and closed for HTTP/1.0 clients. The OutputStream issued must be thread safe so that it can be used in a concurrent environment.

Specified by:

getOutputStream in interface Response

Returns:

an output stream used to write the response body

Throws:

IOException - this is thrown if there was an I/O error

getOutputStream

public OutputStream getOutputStream(int size)
                             throws IOException

Used to write a message body with the Response. The semantics of this OutputStream will be determined by the HTTP version of the client, and whether or not the content length has been set, through the setContentLength method. If the length of the output is not known then the output is chunked for HTTP/1.1 clients and closed for HTTP/1.0 clients. The OutputStream issued must be thread safe so that it can be used in a concurrent environment.

This will ensure that there is buffering done so that the output can be reset using the reset method. This will enable the specified number of bytes to be written without committing the response. This specified size is the minimum size that the response buffer must be.

Specified by:

getOutputStream in interface Response

Parameters:

size - the minimum size that the response buffer must be

Returns:

an output stream used to write the response body

Throws:

IOException - this is thrown if there was an I/O error

getPrintStream

public PrintStream getPrintStream()
                           throws IOException

This method is provided for convenience so that the HTTP content can be written using the print methods provided by the PrintStream. This will basically wrap the getOutputStream with a buffer size of zero.

The retrieved PrintStream uses the charset used to describe the content, with the Content-Type header. This will check the charset parameter of the contents MIME type. So if the Content-Type was text/plain; charset=UTF-8 the resulting PrintStream would encode the written data using the UTF-8 encoding scheme. Care must be taken to ensure that bytes written to the stream are correctly encoded.

Implementations of the Response must guarantee that this can be invoked repeatedly without effecting any issued OutputStream or PrintStream object.

Specified by:

getPrintStream in interface Response

Returns:

a print stream used for writing the response body

Throws:

IOException - this is thrown if there was an I/O error

getPrintStream

public PrintStream getPrintStream(int size)
                           throws IOException

This method is provided for convenience so that the HTTP content can be written using the print methods provided by the PrintStream. This will basically wrap the getOutputStream with a specified buffer size.

The retrieved PrintStream uses the charset used to describe the content, with the Content-Type header. This will check the charset parameter of the contents MIME type. So if the Content-Type was text/plain; charset=UTF-8 the resulting PrintStream would encode the written data using the UTF-8 encoding scheme. Care must be taken to ensure that bytes written to the stream are correctly encoded.

Implementations of the Response must guarantee that this can be invoked repeatedly without effecting any issued OutputStream or PrintStream object.

Specified by:

getPrintStream in interface Response

Parameters:

size - the minimum size that the response buffer must be

Returns:

a print stream used for writing the response body

Throws:

IOException - this is thrown if there was an I/O error

getByteChannel

public WritableByteChannel getByteChannel()
                                   throws IOException

Used to write a message body with the Response. The semantics of this WritableByteChannel are determined by the HTTP version of the client, and whether or not the content length has been set, through the setContentLength method. If the length of the output is not known then the output is chunked for HTTP/1.1 clients and closed for HTTP/1.0 clients.

Specified by:

getByteChannel in interface Response

Returns:

a writable byte channel used to write the message body

Throws:

IOException

getByteChannel

public WritableByteChannel getByteChannel(int size)
                                   throws IOException

Used to write a message body with the Response. The semantics of this WritableByteChannel are determined by the HTTP version of the client, and whether or not the content length has been set, through the setContentLength method. If the length of the output is not known then the output is chunked for HTTP/1.1 clients and closed for HTTP/1.0 clients.

This will ensure that there is buffering done so that the output can be reset using the reset method. This will enable the specified number of bytes to be written without committing the response. This specified size is the minimum size that the response buffer must be.

Specified by:

getByteChannel in interface Response

Parameters:

size - the minimum size that the response buffer must be

Returns:

a writable byte channel used to write the message body

Throws:

IOException

isKeepAlive

public boolean isKeepAlive()

This is used to determine if the HTTP response message is a keep alive message or if the underlying socket was closed. Even if the client requests a connection keep alive and supports persistent connections, the response can still be closed by the server. This can be explicitly indicated by the presence of the Connection HTTP header, it can also be implicitly indicated by using version HTTP/1.0.

Specified by:

isKeepAlive in interface Response

Returns:

this returns true if the connection was closed

isCommitted

public boolean isCommitted()

This can be used to determine whether the Response has been committed. This is true if the Response was committed, either due to an explicit invocation of the commit method or due to the writing of content. If the Response has committed the reset method will not work in resetting content already written.

Specified by:

isCommitted in interface Response

Returns:

true if the response has been fully committed

commit

public void commit()
            throws IOException

This is used to write the headers that where given to the Response. Any further attempts to give headers to the Response will be futile as only the headers that were given at the time of the first commit will be used in the message header.

This also performs some final checks on the headers submitted. This is done to determine the optimal performance of the output. If no specific Connection header has been specified this will set the connection so that HTTP/1.0 closes by default.

Specified by:

commit in interface Response

Throws:

IOException - thrown if there was a problem writing

reset

public void reset()
           throws IOException

This can be used to determine whether the Response has been committed. This is true if the Response was committed, either due to an explicit invocation of the commit method or due to the writing of content. If the Response has committed the reset method will not work in resetting content already written.

Specified by:

reset in interface Response

Throws:

IOException - thrown if there is a problem resetting

close

public void close()
           throws IOException

This is used to close the connection and commit the request. This provides the same semantics as closing the output stream and ensures that the HTTP response is committed. This will throw an exception if the response can not be committed.

Specified by:

close in interface Response

Throws:

IOException - thrown if there is a problem writing

toString

public String toString()

This method returns a string representing the header that was generated for this header. For performance reasons it is better to acquire the character sequence representing the header as it does not require the allocation on new memory.

Specified by:

toString in interface ResponseHeader

Overrides:

toString in class Object

Returns:

this returns a string representation of this response