2020-11-13 11:31:25 +00:00

302 lines
13 KiB
Java

/*
* Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.net.httpserver;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.URI;
import java.util.Map;
/**
* This class encapsulates a HTTP request received and a
* response to be generated in one exchange. It provides methods
* for examining the request from the client, and for building and
* sending the response.
*
* <p> The typical life-cycle of a {@code HttpExchange} is shown in the sequence
* below:
* <ol>
* <li>{@link #getRequestMethod()} to determine the command.
* <li>{@link #getRequestHeaders()} to examine the request headers (if
* needed).
* <li>{@link #getRequestBody()} returns an {@link InputStream} for
* reading the request body. After reading the request body, the stream
* should be closed.
* <li>{@link #getResponseHeaders()} to set any response headers, except
* content-length.
* <li>{@link #sendResponseHeaders(int,long)} to send the response headers.
* Must be called before next step.
* <li>{@link #getResponseBody()} to get a {@link OutputStream} to
* send the response body. When the response body has been written, the
* stream must be closed to terminate the exchange.
* </ol>
*
* <b>Terminating exchanges</b>
* <br>Exchanges are terminated when both the request {@code InputStream} and
* response {@code OutputStream} are closed. Closing the {@code OutputStream},
* implicitly closes the {@code InputStream} (if it is not already closed).
* However, it is recommended to consume all the data from the {@code InputStream}
* before closing it. The convenience method {@link #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.
*
* @since 1.6
*/
public abstract class HttpExchange implements AutoCloseable {
/**
* Constructor for subclasses to call.
*/
protected HttpExchange() {
}
/**
* Returns an immutable {@link Map} containing the HTTP headers that were
* included with this request. The keys in this {@code Map} will be the header
* names, while the values will be a {@link java.util.List} of
* {@linkplain java.lang.String Strings} containing each value that was
* included (either for a header that was listed several times, or one that
* accepts a comma-delimited list of values on a single line). In either of
* these cases, the values for the header name will be presented in the
* order that they were included in the request.
*
* <p> The keys in {@code Map} are case-insensitive.
*
* @return a read-only {@code Map} which can be used to access request headers
*/
public abstract Headers getRequestHeaders();
/**
* Returns a mutable {@link Map} into which the HTTP response headers can be
* stored and which will be transmitted as part of this response. The keys in
* the {@code Map} will be the header names, while the values must be a
* {@link java.util.List} of {@linkplain java.lang.String Strings} containing
* each value that should be included multiple times (in the order that they
* should be included).
*
* <p> The keys in {@code Map} are case-insensitive.
*
* @return a writable {@code Map} which can be used to set response headers.
*/
public abstract Headers getResponseHeaders();
/**
* Get the request {@link URI}.
*
* @return the request {@code URI}
*/
public abstract URI getRequestURI();
/**
* Get the request method.
*
* @return the request method
*/
public abstract String getRequestMethod();
/**
* Get the {@link HttpContext} for this exchange.
*
* @return the {@code HttpContext}
*/
public abstract HttpContext getHttpContext();
/**
* Ends this exchange by doing the following in sequence:
* <ol>
* <li> close the request {@link InputStream}, if not already closed.
* <li> close the response {@link OutputStream}, if not already closed.
* </ol>
*/
public abstract void close();
/**
* Returns a stream from which the request body can be read.
* Multiple calls to this method will return the same stream.
* It is recommended that applications should consume (read) all of the data
* from this stream before closing it. If a stream is closed before all data
* has been read, then the {@link InputStream#close()} call will read
* and discard remaining data (up to an implementation specific number of
* bytes).
*
* @return the stream from which the request body can be read
*/
public abstract InputStream getRequestBody();
/**
* Returns a stream to which the response body must be
* written. {@link #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.
*
* <p> Closing this stream implicitly closes the {@link InputStream}
* returned from {@link #getRequestBody()} (if it is not already closed).
*
* <p> If the call to {@link #sendResponseHeaders(int, long)} 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 the write method of {@link OutputStream} will throw an {@code IOException}.
* If too few bytes are written then the stream
* {@link OutputStream#close()} will throw an {@code IOException}.
* In both cases, the exchange is aborted and the underlying TCP connection
* closed.
*
* @return the stream to which the response body is written
*/
public abstract OutputStream getResponseBody();
/**
* 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. The response body length is also specified as follows. If the
* response length parameter is greater than {@code zero}, this specifies an
* exact number of bytes to send and the application must send that exact
* amount of data. If the response length parameter is {@code 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
* {@link OutputStream}.
* If response length has the value {@code -1} then no response body is
* being sent.
*
* <p> 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.
*
* <p> This method must be called prior to calling {@link #getResponseBody()}.
*
* @implNote This implementation allows the caller to instruct the
* server to force a connection close after the exchange terminates, by
* supplying a {@code Connection: close} header to the {@linkplain
* #getResponseHeaders() response headers} before {@code sendResponseHeaders}
* is called.
*
* @param rCode the response code to send
* @param responseLength if {@literal > 0}, specifies a fixed response body
* length and that exact number of bytes must be written
* to the stream acquired from {@link #getResponseCode()}
* If {@literal == 0}, then chunked encoding is used,
* and an arbitrary number of bytes may be written.
* If {@literal <= -1}, then no response body length is
* specified and no response body may be written.
* @throws IOException if the response headers have already been sent or an I/O error occurs
* @see HttpExchange#getResponseBody()
*/
public abstract void sendResponseHeaders(int rCode, long responseLength) throws IOException;
/**
* Returns the address of the remote entity invoking this request.
*
* @return the {@link InetSocketAddress} of the caller
*/
public abstract InetSocketAddress getRemoteAddress();
/**
* Returns the response code, if it has already been set.
*
* @return the response code, if available. {@code -1} if not available yet.
*/
public abstract int getResponseCode();
/**
* Returns the local address on which the request was received.
*
* @return the {@link InetSocketAddress} of the local interface
*/
public abstract InetSocketAddress getLocalAddress();
/**
* Returns the protocol string from the request in the form
* <i>protocol/majorVersion.minorVersion</i>. For example,
* "{@code HTTP/1.1}".
*
* @return the protocol string from the request
*/
public abstract String getProtocol();
/**
* {@link Filter} modules may store arbitrary objects with {@code HttpExchange}
* instances as an out-of-band communication mechanism. Other filters
* or the exchange handler may then access these objects.
*
* <p> Each {@code Filter} class will document the attributes which they make
* available.
*
* @param name the name of the attribute to retrieve
* @return the attribute object, or {@code null} if it does not exist
* @throws NullPointerException if name is {@code null}
*/
public abstract Object getAttribute(String name);
/**
* {@link Filter} modules may store arbitrary objects with {@code HttpExchange}
* instances as an out-of-band communication mechanism. Other filters
* or the exchange handler may then access these objects.
*
* <p> Each {@code Filter} class will document the attributes which they make
* available.
*
* @param name the name to associate with the attribute value
* @param value the object to store as the attribute value. {@code null}
* value is permitted.
* @throws NullPointerException if name is {@code null}
*/
public abstract void setAttribute(String name, Object value);
/**
* Used by {@linkplain com.sun.net.httpserver.Filter Filters} to wrap either
* (or both) of this exchange's {@link InputStream} and
* {@link OutputStream}, with the given filtered streams so that
* subsequent calls to {@link #getRequestBody()} will return the given
* {@code InputStream}, and calls to {@link #getResponseBody()} will return
* the given {@code OutputStream}. The streams provided to this call must wrap
* the original streams, and may be (but are not required to be) sub-classes
* of {@link java.io.FilterInputStream} and {@link java.io.FilterOutputStream}.
*
* @param i the filtered input stream to set as this object's
* {@code Inputstream}, or {@code null} if no change
* @param o the filtered output stream to set as this object's
* {@code Outputstream}, or {@code null} if no change
*/
public abstract void setStreams(InputStream i, OutputStream o);
/**
* If an authenticator is set on the {@link HttpContext} that owns this exchange,
* then this method will return the {@link HttpPrincipal} that represents
* the authenticated user for this {@code HttpExchange}.
*
* @return the {@code HttpPrincipal}, or {@code null} if no authenticator is set
*/
public abstract HttpPrincipal getPrincipal();
}