JDK8/Java8源码在线阅读
/*
* Copyright (c) 1996, 2013, 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 java.net;
import java.io.InputStream;
import java.io.IOException;
import java.security.Permission;
import java.util.Date;
/**
* A URLConnection with support for HTTP-specific features. See
* <A HREF="http://www.w3.org/pub/WWW/Protocols/"> the spec </A> for
* details.
* <p>
*
* Each HttpURLConnection instance is used to make a single request
* but the underlying network connection to the HTTP server may be
* transparently shared by other instances. Calling the close() methods
* on the InputStream or OutputStream of an HttpURLConnection
* after a request may free network resources associated with this
* instance but has no effect on any shared persistent connection.
* Calling the disconnect() method may close the underlying socket
* if a persistent connection is otherwise idle at that time.
*
* <P>The HTTP protocol handler has a few settings that can be accessed through
* System Properties. This covers
* <a href="doc-files/net-properties.html#Proxies">Proxy settings</a> as well as
* <a href="doc-files/net-properties.html#MiscHTTP"> various other settings</a>.
* </P>
* <p>
* <b>Security permissions</b>
* <p>
* If a security manager is installed, and if a method is called which results in an
* attempt to open a connection, the caller must possess either:-
* <ul><li>a "connect" {@link SocketPermission} to the host/port combination of the
* destination URL or</li>
* <li>a {@link URLPermission} that permits this request.</li>
* </ul><p>
* If automatic redirection is enabled, and this request is redirected to another
* destination, then the caller must also have permission to connect to the
* redirected host/URL.
*
* @see java.net.HttpURLConnection#disconnect()
* @since JDK1.1
*/
abstract public class HttpURLConnection extends URLConnection {
/* instance variables */
/**
* The HTTP method (GET,POST,PUT,etc.).
*/
protected String method = "GET";
/**
* The chunk-length when using chunked encoding streaming mode for output.
* A value of {@code -1} means chunked encoding is disabled for output.
* @since 1.5
*/
protected int chunkLength = -1;
/**
* The fixed content-length when using fixed-length streaming mode.
* A value of {@code -1} means fixed-length streaming mode is disabled
* for output.
*
* <P> <B>NOTE:</B> {@link #fixedContentLengthLong} is recommended instead
* of this field, as it allows larger content lengths to be set.
*
* @since 1.5
*/
protected int fixedContentLength = -1;
/**
* The fixed content-length when using fixed-length streaming mode.
* A value of {@code -1} means fixed-length streaming mode is disabled
* for output.
*
* @since 1.7
*/
protected long fixedContentLengthLong = -1;
/**
* Returns the key for the {@code n}<sup>th</sup> header field.
* Some implementations may treat the {@code 0}<sup>th</sup>
* header field as special, i.e. as the status line returned by the HTTP
* server. In this case, {@link #getHeaderField(int) getHeaderField(0)} returns the status
* line, but {@code getHeaderFieldKey(0)} returns null.
*
* @param n an index, where {@code n >=0}.
* @return the key for the {@code n}<sup>th</sup> header field,
* or {@code null} if the key does not exist.
*/
public String getHeaderFieldKey (int n) {
return null;
}
/**
* This method is used to enable streaming of a HTTP request body
* without internal buffering, when the content length is known in
* advance.
* <p>
* An exception will be thrown if the application
* attempts to write more data than the indicated
* content-length, or if the application closes the OutputStream
* before writing the indicated amount.
* <p>
* When output streaming is enabled, authentication
* and redirection cannot be handled automatically.
* A HttpRetryException will be thrown when reading
* the response if authentication or redirection are required.
* This exception can be queried for the details of the error.
* <p>
* This method must be called before the URLConnection is connected.
* <p>
* <B>NOTE:</B> {@link #setFixedLengthStreamingMode(long)} is recommended
* instead of this method as it allows larger content lengths to be set.
*
* @param contentLength The number of bytes which will be written
* to the OutputStream.
*
* @throws IllegalStateException if URLConnection is already connected
* or if a different streaming mode is already enabled.
*
* @throws IllegalArgumentException if a content length less than
* zero is specified.
*
* @see #setChunkedStreamingMode(int)
* @since 1.5
*/
public void setFixedLengthStreamingMode (int contentLength) {
if (connected) {
throw new IllegalStateException ("Already connected");
}
if (chunkLength != -1) {
throw new IllegalStateException ("Chunked encoding streaming mode set");
}
if (contentLength < 0) {
throw new IllegalArgumentException ("invalid content length");
}
fixedContentLength = contentLength;
}
/**
* This method is used to enable streaming of a HTTP request body
* without internal buffering, when the content length is known in
* advance.
*
* <P> An exception will be thrown if the application attempts to write
* more data than the indicated content-length, or if the application
* closes the OutputStream before writing the indicated amount.
*
* <P> When output streaming is enabled, authentication and redirection
* cannot be handled automatically. A {@linkplain HttpRetryException} will
* be thrown when reading the response if authentication or redirection
* are required. This exception can be queried for the details of the
* error.
*
* <P> This method must be called before the URLConnection is connected.
*
* <P> The content length set by invoking this method takes precedence
* over any value set by {@link #setFixedLengthStreamingMode(int)}.
*
* @param contentLength
* The number of bytes which will be written to the OutputStream.
*
* @throws IllegalStateException
* if URLConnection is already connected or if a different
* streaming mode is already enabled.
*
* @throws IllegalArgumentException
* if a content length less than zero is specified.
*
* @since 1.7
*/
public void setFixedLengthStreamingMode(long contentLength) {
if (connected) {
throw new IllegalStateException("Already connected");
}
if (chunkLength != -1) {
throw new IllegalStateException(
"Chunked encoding streaming mode set");
}
if (contentLength < 0) {
throw new IllegalArgumentException("invalid content length");
}
fixedContentLengthLong = contentLength;
}
/* Default chunk size (including chunk header) if not specified;
* we want to keep this in sync with the one defined in
* sun.net.www.http.ChunkedOutputStream
*/
private static final int DEFAULT_CHUNK_SIZE = 4096;
/**
* This method is used to enable streaming of a HTTP request body
* without internal buffering, when the content length is <b>not</b>
* known in advance. In this mode, chunked transfer encoding
* is used to send the request body. Note, not all HTTP servers
* support this mode.
* <p>
* When output streaming is enabled, authentication
* and redirection cannot be handled automatically.
* A HttpRetryException will be thrown when reading
* the response if authentication or redirection are required.
* This exception can be queried for the details of the error.
* <p>
* This method must be called before the URLConnection is connected.
*
* @param chunklen The number of bytes to write in each chunk.
* If chunklen is less than or equal to zero, a default
* value will be used.
*
* @throws IllegalStateException if URLConnection is already connected
* or if a different streaming mode is already enabled.
*
* @see #setFixedLengthStreamingMode(int)
* @since 1.5
*/
public void setChunkedStreamingMode (int chunklen) {
if (connected) {
throw new IllegalStateException ("Can't set streaming mode: already connected");
}
if (fixedContentLength != -1 || fixedContentLengthLong != -1) {
throw new IllegalStateException ("Fixed length streaming mode set");
}
chunkLength = chunklen <=0? DEFAULT_CHUNK_SIZE : chunklen;
}
/**
* Returns the value for the {@code n}<sup>th</sup> header field.
* Some implementations may treat the {@code 0}<sup>th</sup>
* header field as special, i.e. as the status line returned by the HTTP
* server.
* <p>
* This method can be used in conjunction with the
* {@link #getHeaderFieldKey getHeaderFieldKey} method to iterate through all
* the headers in the message.
*
* @param n an index, where {@code n>=0}.
* @return the value of the {@code n}<sup>th</sup> header field,
* or {@code null} if the value does not exist.
* @see java.net.HttpURLConnection#getHeaderFieldKey(int)
*/
public String getHeaderField(int n) {
return null;
}
/**
* An {@code int} representing the three digit HTTP Status-Code.
* <ul>
* <li> 1xx: Informational
* <li> 2xx: Success
* <li> 3xx: Redirection
* <li> 4xx: Client Error
* <li> 5xx: Server Error
* </ul>
*/
protected int responseCode = -1;
/**
* The HTTP response message.
*/
protected String responseMessage = null;
/* static variables */
/* do we automatically follow redirects? The default is true. */
private static boolean followRedirects = true;
/**
* If {@code true}, the protocol will automatically follow redirects.
* If {@code false}, the protocol will not automatically follow
* redirects.
* <p>
* This field is set by the {@code setInstanceFollowRedirects}
* method. Its value is returned by the {@code getInstanceFollowRedirects}
* method.
* <p>
* Its default value is based on the value of the static followRedirects
* at HttpURLConnection construction time.
*
* @see java.net.HttpURLConnection#setInstanceFollowRedirects(boolean)
* @see java.net.HttpURLConnection#getInstanceFollowRedirects()
* @see java.net.HttpURLConnection#setFollowRedirects(boolean)
*/
protected boolean instanceFollowRedirects = followRedirects;
/* valid HTTP methods */
private static final String[] methods = {
"GET", "POST", "HEAD", "OPTIONS", "PUT", "DELETE", "TRACE"
};
/**
* Constructor for the HttpURLConnection.
* @param u the URL
*/
protected HttpURLConnection (URL u) {
super(u);
}
/**
* Sets whether HTTP redirects (requests with response code 3xx) should
* be automatically followed by this class. True by default. Applets
* cannot change this variable.
* <p>
* If there is a security manager, this method first calls
* the security manager's {@code checkSetFactory} method
* to ensure the operation is allowed.
* This could result in a SecurityException.
*
* @param set a {@code boolean} indicating whether or not
* to follow HTTP redirects.
* @exception SecurityException if a security manager exists and its
* {@code checkSetFactory} method doesn't
* allow the operation.
* @see SecurityManager#checkSetFactory
* @see #getFollowRedirects()
*/
public static void setFollowRedirects(boolean set) {
SecurityManager sec = System.getSecurityManager();
if (sec != null) {
// seems to be the best check here...
sec.checkSetFactory();
}
followRedirects = set;
}
/**
* Returns a {@code boolean} indicating
* whether or not HTTP redirects (3xx) should
* be automatically followed.
*
* @return {@code true} if HTTP redirects should
* be automatically followed, {@code false} if not.
* @see #setFollowRedirects(boolean)
*/
public static boolean getFollowRedirects() {
return followRedirects;
}
/**
* Sets whether HTTP redirects (requests with response code 3xx) should
* be automatically followed by this {@code HttpURLConnection}
* instance.
* <p>
* The default value comes from followRedirects, which defaults to
* true.
*
* @param followRedirects a {@code boolean} indicating
* whether or not to follow HTTP redirects.
*
* @see java.net.HttpURLConnection#instanceFollowRedirects
* @see #getInstanceFollowRedirects
* @since 1.3
*/
public void setInstanceFollowRedirects(boolean followRedirects) {
instanceFollowRedirects = followRedirects;
}
/**
* Returns the value of this {@code HttpURLConnection}'s
* {@code instanceFollowRedirects} field.
*
* @return the value of this {@code HttpURLConnection}'s
* {@code instanceFollowRedirects} field.
* @see java.net.HttpURLConnection#instanceFollowRedirects
* @see #setInstanceFollowRedirects(boolean)
* @since 1.3
*/
public boolean getInstanceFollowRedirects() {
return instanceFollowRedirects;
}
/**
* Set the method for the URL request, one of:
* <UL>
* <LI>GET
* <LI>POST
* <LI>HEAD
* <LI>OPTIONS
* <LI>PUT
* <LI>DELETE
* <LI>TRACE
* </UL> are legal, subject to protocol restrictions. The default
* method is GET.
*
* @param method the HTTP method
* @exception ProtocolException if the method cannot be reset or if
* the requested method isn't valid for HTTP.
* @exception SecurityException if a security manager is set and the
* method is "TRACE", but the "allowHttpTrace"
* NetPermission is not granted.
* @see #getRequestMethod()
*/
public void setRequestMethod(String method) throws ProtocolException {
if (connected) {
throw new ProtocolException("Can't reset method: already connected");
}
// This restriction will prevent people from using this class to
// experiment w/ new HTTP methods using java. But it should
// be placed for security - the request String could be
// arbitrarily long.
for (int i = 0; i < methods.length; i++) {
if (methods[i].equals(method)) {
if (method.equals("TRACE")) {
SecurityManager s = System.getSecurityManager();
if (s != null) {
s.checkPermission(new NetPermission("allowHttpTrace"));
}
}
this.method = method;
return;
}
}
throw new ProtocolException("Invalid HTTP method: " + method);
}
/**
* Get the request method.
* @return the HTTP request method
* @see #setRequestMethod(java.lang.String)
*/
public String getRequestMethod() {
return method;
}
/**
* Gets the status code from an HTTP response message.
* For example, in the case of the following status lines:
* <PRE>
* HTTP/1.0 200 OK
* HTTP/1.0 401 Unauthorized
* </PRE>
* It will return 200 and 401 respectively.
* Returns -1 if no code can be discerned
* from the response (i.e., the response is not valid HTTP).
* @throws IOException if an error occurred connecting to the server.
* @return the HTTP Status-Code, or -1
*/
public int getResponseCode() throws IOException {
/*
* We're got the response code already
*/
if (responseCode != -1) {
return responseCode;
}
/*
* Ensure that we have connected to the server. Record
* exception as we need to re-throw it if there isn't
* a status line.
*/
Exception exc = null;
try {
getInputStream();
} catch (Exception e) {
exc = e;
}
/*
* If we can't a status-line then re-throw any exception
* that getInputStream threw.
*/
String statusLine = getHeaderField(0);
if (statusLine == null) {
if (exc != null) {
if (exc instanceof RuntimeException)
throw (RuntimeException)exc;
else
throw (IOException)exc;
}
return -1;
}
/*
* Examine the status-line - should be formatted as per
* section 6.1 of RFC 2616 :-
*
* Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase
*
* If status line can't be parsed return -1.
*/
if (statusLine.startsWith("HTTP/1.")) {
int codePos = statusLine.indexOf(' ');
if (codePos > 0) {
int phrasePos = statusLine.indexOf(' ', codePos+1);
if (phrasePos > 0 && phrasePos < statusLine.length()) {
responseMessage = statusLine.substring(phrasePos+1);
}
// deviation from RFC 2616 - don't reject status line
// if SP Reason-Phrase is not included.
if (phrasePos < 0)
phrasePos = statusLine.length();
try {
responseCode = Integer.parseInt
(statusLine.substring(codePos+1, phrasePos));
return responseCode;
} catch (NumberFormatException e) { }
}
}
return -1;
}
/**
* Gets the HTTP response message, if any, returned along with the
* response code from a server. From responses like:
* <PRE>
* HTTP/1.0 200 OK
* HTTP/1.0 404 Not Found
* </PRE>
* Extracts the Strings "OK" and "Not Found" respectively.
* Returns null if none could be discerned from the responses
* (the result was not valid HTTP).
* @throws IOException if an error occurred connecting to the server.
* @return the HTTP response message, or {@code null}
*/
public String getResponseMessage() throws IOException {
getResponseCode();
return responseMessage;
}
@SuppressWarnings("deprecation")
public long getHeaderFieldDate(String name, long Default) {
String dateString = getHeaderField(name);
try {
if (dateString.indexOf("GMT") == -1) {
dateString = dateString+" GMT";
}
return Date.parse(dateString);
} catch (Exception e) {
}
return Default;
}
/**
* Indicates that other requests to the server
* are unlikely in the near future. Calling disconnect()
* should not imply that this HttpURLConnection
* instance can be reused for other requests.
*/
public abstract void disconnect();
/**
* Indicates if the connection is going through a proxy.
* @return a boolean indicating if the connection is
* using a proxy.
*/
public abstract boolean usingProxy();
/**
* Returns a {@link SocketPermission} object representing the
* permission necessary to connect to the destination host and port.
*
* @exception IOException if an error occurs while computing
* the permission.
*
* @return a {@code SocketPermission} object representing the
* permission necessary to connect to the destination
* host and port.
*/
public Permission getPermission() throws IOException {
int port = url.getPort();
port = port < 0 ? 80 : port;
String host = url.getHost() + ":" + port;
Permission permission = new SocketPermission(host, "connect");
return permission;
}
/**
* Returns the error stream if the connection failed
* but the server sent useful data nonetheless. The
* typical example is when an HTTP server responds
* with a 404, which will cause a FileNotFoundException
* to be thrown in connect, but the server sent an HTML
* help page with suggestions as to what to do.
*
* <p>This method will not cause a connection to be initiated. If
* the connection was not connected, or if the server did not have
* an error while connecting or if the server had an error but
* no error data was sent, this method will return null. This is
* the default.
*
* @return an error stream if any, null if there have been no
* errors, the connection is not connected or the server sent no
* useful data.
*/
public InputStream getErrorStream() {
return null;
}
/**
* The response codes for HTTP, as of version 1.1.
*/
// REMIND: do we want all these??
// Others not here that we do want??
/* 2XX: generally "OK" */
/**
* HTTP Status-Code 200: OK.
*/
public static final int HTTP_OK = 200;
/**
* HTTP Status-Code 201: Created.
*/
public static final int HTTP_CREATED = 201;
/**
* HTTP Status-Code 202: Accepted.
*/
public static final int HTTP_ACCEPTED = 202;
/**
* HTTP Status-Code 203: Non-Authoritative Information.
*/
public static final int HTTP_NOT_AUTHORITATIVE = 203;
/**
* HTTP Status-Code 204: No Content.
*/
public static final int HTTP_NO_CONTENT = 204;
/**
* HTTP Status-Code 205: Reset Content.
*/
public static final int HTTP_RESET = 205;
/**
* HTTP Status-Code 206: Partial Content.
*/
public static final int HTTP_PARTIAL = 206;
/* 3XX: relocation/redirect */
/**
* HTTP Status-Code 300: Multiple Choices.
*/
public static final int HTTP_MULT_CHOICE = 300;
/**
* HTTP Status-Code 301: Moved Permanently.
*/
public static final int HTTP_MOVED_PERM = 301;
/**
* HTTP Status-Code 302: Temporary Redirect.
*/
public static final int HTTP_MOVED_TEMP = 302;
/**
* HTTP Status-Code 303: See Other.
*/
public static final int HTTP_SEE_OTHER = 303;
/**
* HTTP Status-Code 304: Not Modified.
*/
public static final int HTTP_NOT_MODIFIED = 304;
/**
* HTTP Status-Code 305: Use Proxy.
*/
public static final int HTTP_USE_PROXY = 305;
/* 4XX: client error */
/**
* HTTP Status-Code 400: Bad Request.
*/
public static final int HTTP_BAD_REQUEST = 400;
/**代码未完, 请加载全部代码(NowJava.com).**/
关注时代Java
关注时代Java