@Exported public abstract class HttpExchange extends Object
The typical life-cycle of a HttpExchange is shown in the sequence below.
getRequestMethod() to determine the command
 getRequestHeaders() to examine the request headers (if needed)
 getRequestBody() returns a InputStream for reading the request body.
     After reading the request body, the stream is close.
 getResponseHeaders() to set any response headers, except content-length
 sendResponseHeaders(int,long) to send the response headers. Must be called before
 next step.
 getResponseBody() to get a OutputStream to send the response body.
      When the response body has been written, the stream must be closed to terminate the exchange.
 close() does all of these tasks.
 Closing an exchange without consuming all of the request body is not an error
 but may make the underlying TCP connection unusable for following exchanges.
 The effect of failing to terminate an exchange is undefined, but will typically
 result in resources failing to be freed/reused.| Modifier | Constructor and Description | 
|---|---|
| protected  | HttpExchange() | 
| Modifier and Type | Method and Description | 
|---|---|
| abstract void | close()Ends this exchange by doing the following in sequence: | 
| abstract Object | getAttribute(String name)Filter modules may store arbitrary objects with HttpExchange
 instances as an out-of-band communication mechanism. | 
| abstract HttpContext | getHttpContext()Get the HttpContext for this exchange | 
| abstract InetSocketAddress | getLocalAddress()Returns the local address on which the request was received | 
| abstract HttpPrincipal | getPrincipal()If an authenticator is set on the HttpContext that owns this exchange,
 then this method will return the  HttpPrincipalthat represents
 the authenticated user for this HttpExchange. | 
| abstract String | getProtocol()Returns the protocol string from the request in the form
 protocol/majorVersion.minorVersion. | 
| abstract InetSocketAddress | getRemoteAddress()Returns the address of the remote entity invoking this request | 
| abstract InputStream | getRequestBody()returns a stream from which the request body can be read. | 
| abstract Headers | getRequestHeaders()Returns an immutable Map containing the HTTP headers that were
 included with this request. | 
| abstract String | getRequestMethod()Get the request method | 
| abstract URI | getRequestURI()Get the request URI | 
| abstract OutputStream | getResponseBody()returns a stream to which the response body must be
 written. | 
| abstract int | getResponseCode()Returns the response code, if it has already been set | 
| abstract Headers | getResponseHeaders()Returns a mutable Map into which the HTTP response headers can be stored
 and which will be transmitted as part of this response. | 
| abstract void | sendResponseHeaders(int rCode,
                   long responseLength)Starts sending the response back to the client using the current set of response headers
 and the numeric response code as specified in this method. | 
| abstract void | setAttribute(String name,
            Object value)Filter modules may store arbitrary objects with HttpExchange
 instances as an out-of-band communication mechanism. | 
| abstract void | setStreams(InputStream i,
          OutputStream o)Used by Filters to wrap either (or both) of this exchange's InputStream
 and OutputStream, with the given filtered streams so
 that subsequent calls to  getRequestBody()will
 return the givenInputStream, and calls togetResponseBody()will return the givenOutputStream. | 
public abstract Headers getRequestHeaders()
The keys in Map are case-insensitive.
public abstract Headers getResponseHeaders()
The keys in Map are case-insensitive.
public abstract URI getRequestURI()
public abstract String getRequestMethod()
public abstract HttpContext getHttpContext()
public abstract void close()
public abstract InputStream getRequestBody()
public abstract OutputStream getResponseBody()
sendResponseHeaders(int,long)) must be called prior to calling
 this method. Multiple calls to this method (for the same exchange)
 will return the same stream. In order to correctly terminate
 each exchange, the output stream must be closed, even if no
 response body is being sent.
 
 Closing this stream implicitly
 closes the InputStream returned from getRequestBody()
 (if it is not already closed).
 
If the call to sendResponseHeaders() specified a fixed response body length, then the exact number of bytes specified in that call must be written to this stream. If too many bytes are written, then write() will throw an IOException. If too few bytes are written then the stream close() will throw an IOException. In both cases, the exchange is aborted and the underlying TCP connection closed.
public abstract void sendResponseHeaders(int rCode,
                                         long responseLength)
                                  throws IOException
zero, then chunked transfer encoding is
 used and an arbitrary amount of data may be sent. The application terminates the
 response body by closing the OutputStream. If response length has the value -1
 then no response body is being sent.
 If the content-length response header has not already been set then this is set to the appropriate value depending on the response length parameter.
 This method must be called prior to calling getResponseBody().
rCode - the response code to sendresponseLength - if > 0, specifies a fixed response body length
        and that exact number of bytes must be written
        to the stream acquired from getResponseBody(), or else
        if equal to 0, then chunked encoding is used,
        and an arbitrary number of bytes may be written.
        if <= -1, then no response body length is specified and
        no response body may be written.IOExceptiongetResponseBody()public abstract InetSocketAddress getRemoteAddress()
public abstract int getResponseCode()
-1 if not available yet.public abstract InetSocketAddress getLocalAddress()
public abstract String getProtocol()
public abstract Object getAttribute(String name)
Each Filter class will document the attributes which they make available.
name - the name of the attribute to retrieveNullPointerException - if name is nullpublic abstract void setAttribute(String name, Object value)
Each Filter class will document the attributes which they make available.
name - the name to associate with the attribute valuevalue - the object to store as the attribute value. null
 value is permitted.NullPointerException - if name is nullpublic abstract void setStreams(InputStream i, OutputStream o)
getRequestBody() will
 return the given InputStream, and calls to
 getResponseBody() will return the given
 OutputStream. The streams provided to this
 call must wrap the original streams, and may be (but are not
 required to be) sub-classes of FilterInputStream
 and FilterOutputStream.i - the filtered input stream to set as this object's inputstream,
          or null if no change.o - the filtered output stream to set as this object's outputstream,
          or null if no change.public abstract HttpPrincipal getPrincipal()
HttpPrincipal that represents
 the authenticated user for this HttpExchange.null if no authenticator is set.
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