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1875 lines (1712 loc) · 68.2 KB
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/*
* Copyright (c) 1995, 2025, 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.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Hashtable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.Date;
import java.util.Iterator;
import java.util.Objects;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import java.util.StringTokenizer;
import java.util.Collections;
import java.util.Locale;
import java.util.Map;
import java.util.List;
import java.security.Permission;
import sun.security.util.SecurityConstants;
import sun.net.www.MessageHeader;
/**
* The abstract class {@code URLConnection} is the superclass
* of all classes that represent a communications link between the
* application and a URL. Instances of this class can be used both to
* read from and to write to the resource referenced by the URL.
*
* <p>
* In general, creating a connection to a URL is a multistep process:
* <ol>
* <li>The connection object is created by invoking the
* {@link URL#openConnection() openConnection} method on a URL.
* <li>The setup parameters and general request properties are manipulated.
* <li>The actual connection to the remote object is made, using the
* {@link #connect() connect} method.
* <li>The remote object becomes available. The header fields and the contents
* of the remote object can be accessed.
* </ol>
* <p>
* The setup parameters are modified using the following methods:
* <ul>
* <li>{@code setAllowUserInteraction}
* <li>{@code setDoInput}
* <li>{@code setDoOutput}
* <li>{@code setIfModifiedSince}
* <li>{@code setUseCaches}
* </ul>
* <p>
* and the general request properties are modified using the method:
* <ul>
* <li>{@code setRequestProperty}
* </ul>
* <p>
* Default values for the {@code AllowUserInteraction} and
* {@code UseCaches} parameters can be set using the methods
* {@code setDefaultAllowUserInteraction} and
* {@code setDefaultUseCaches}.
* <p>
* Each of the above {@code set} methods has a corresponding
* {@code get} method to retrieve the value of the parameter or
* general request property. The specific parameters and general
* request properties that are applicable are protocol specific.
* <p>
* The following methods are used to access the header fields and
* the contents after the connection is made to the remote object:
* <ul>
* <li>{@code getContent}
* <li>{@code getHeaderField}
* <li>{@code getInputStream}
* <li>{@code getOutputStream}
* </ul>
* <p>
* Certain header fields are accessed frequently. The methods:
* <ul>
* <li>{@code getContentEncoding}
* <li>{@code getContentLength}
* <li>{@code getContentType}
* <li>{@code getDate}
* <li>{@code getExpiration}
* <li>{@code getLastModified}
* </ul>
* <p>
* provide convenient access to these fields. The
* {@code getContentType} method is used by the
* {@code getContent} method to determine the type of the remote
* object; subclasses may find it convenient to override the
* {@code getContentType} method.
* <p>
* In the common case, all of the pre-connection parameters and
* general request properties can be ignored: the pre-connection
* parameters and request properties default to sensible values. For
* most clients of this interface, there are only two interesting
* methods: {@code getInputStream} and {@code getContent},
* which are mirrored in the {@code URL} class by convenience methods.
* <p>
* More information on the request properties and header fields of
* an {@code http} connection can be found at:
* <blockquote><pre>
* <a href="http://www.ietf.org/rfc/rfc2616.txt">http://www.ietf.org/rfc/rfc2616.txt</a>
* </pre></blockquote>
*
* Invoking the {@code close()} methods on the {@code InputStream} or {@code OutputStream} of an
* {@code URLConnection} after a request may free network resources associated with this
* instance, unless particular protocol specifications specify different behaviours
* for it.
*
* @spec https://www.rfc-editor.org/info/rfc2616
* RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1
* @author James Gosling
* @see java.net.URL#openConnection()
* @see java.net.URLConnection#connect()
* @see java.net.URLConnection#getContent()
* @see java.net.URLConnection#getContentEncoding()
* @see java.net.URLConnection#getContentLength()
* @see java.net.URLConnection#getContentType()
* @see java.net.URLConnection#getDate()
* @see java.net.URLConnection#getExpiration()
* @see java.net.URLConnection#getHeaderField(int)
* @see java.net.URLConnection#getHeaderField(java.lang.String)
* @see java.net.URLConnection#getInputStream()
* @see java.net.URLConnection#getLastModified()
* @see java.net.URLConnection#getOutputStream()
* @see java.net.URLConnection#setAllowUserInteraction(boolean)
* @see java.net.URLConnection#setDefaultUseCaches(boolean)
* @see java.net.URLConnection#setDoInput(boolean)
* @see java.net.URLConnection#setDoOutput(boolean)
* @see java.net.URLConnection#setIfModifiedSince(long)
* @see java.net.URLConnection#setRequestProperty(java.lang.String, java.lang.String)
* @see java.net.URLConnection#setUseCaches(boolean)
* @since 1.0
*/
public abstract class URLConnection {
/**
* The URL represents the remote object on the World Wide Web to
* which this connection is opened.
* <p>
* The value of this field can be accessed by the
* {@code getURL} method.
* <p>
* The default value of this variable is the value of the URL
* argument in the {@code URLConnection} constructor.
*
* @see java.net.URLConnection#getURL()
* @see java.net.URLConnection#url
*/
protected URL url;
/**
* This variable is set by the {@code setDoInput} method. Its
* value is returned by the {@code getDoInput} method.
* <p>
* A URL connection can be used for input and/or output. Setting the
* {@code doInput} flag to {@code true} indicates that
* the application intends to read data from the URL connection.
* <p>
* The default value of this field is {@code true}.
*
* @see java.net.URLConnection#getDoInput()
* @see java.net.URLConnection#setDoInput(boolean)
*/
protected boolean doInput = true;
/**
* This variable is set by the {@code setDoOutput} method. Its
* value is returned by the {@code getDoOutput} method.
* <p>
* A URL connection can be used for input and/or output. Setting the
* {@code doOutput} flag to {@code true} indicates
* that the application intends to write data to the URL connection.
* <p>
* The default value of this field is {@code false}.
*
* @see java.net.URLConnection#getDoOutput()
* @see java.net.URLConnection#setDoOutput(boolean)
*/
protected boolean doOutput = false;
private static boolean defaultAllowUserInteraction = false;
/**
* If {@code true}, this {@code URL} is being examined in
* a context in which it makes sense to allow user interactions such
* as popping up an authentication dialog. If {@code false},
* then no user interaction is allowed.
* <p>
* The value of this field can be set by the
* {@code setAllowUserInteraction} method.
* Its value is returned by the
* {@code getAllowUserInteraction} method.
* Its default value is the value of the argument in the last invocation
* of the {@code setDefaultAllowUserInteraction} method.
*
* @see java.net.URLConnection#getAllowUserInteraction()
* @see java.net.URLConnection#setAllowUserInteraction(boolean)
* @see java.net.URLConnection#setDefaultAllowUserInteraction(boolean)
*/
protected boolean allowUserInteraction = defaultAllowUserInteraction;
private static volatile boolean defaultUseCaches = true;
/**
* If {@code true}, the protocol is allowed to use caching
* whenever it can. If {@code false}, the protocol must always
* try to get a fresh copy of the object.
* <p>
* This field is set by the {@code setUseCaches} method. Its
* value is returned by the {@code getUseCaches} method.
* <p>
* Its default value is the value given in the last invocation of the
* {@code setDefaultUseCaches} method.
* <p>
* The default setting may be overridden per protocol with
* {@link #setDefaultUseCaches(String,boolean)}.
*
* @see java.net.URLConnection#setUseCaches(boolean)
* @see java.net.URLConnection#getUseCaches()
* @see java.net.URLConnection#setDefaultUseCaches(boolean)
*/
protected boolean useCaches;
private static final ConcurrentHashMap<String,Boolean> defaultCaching =
new ConcurrentHashMap<>();
/**
* Some protocols support skipping the fetching of the object unless
* the object has been modified more recently than a certain time.
* <p>
* A nonzero value gives a time as the number of milliseconds since
* January 1, 1970, GMT. The object is fetched only if it has been
* modified more recently than that time.
* <p>
* This variable is set by the {@code setIfModifiedSince}
* method. Its value is returned by the
* {@code getIfModifiedSince} method.
* <p>
* The default value of this field is {@code 0}, indicating
* that the fetching must always occur.
*
* @see java.net.URLConnection#getIfModifiedSince()
* @see java.net.URLConnection#setIfModifiedSince(long)
*/
protected long ifModifiedSince = 0;
/**
* If {@code false}, this connection object has not created a
* communications link to the specified URL. If {@code true},
* the communications link has been established.
*/
protected boolean connected = false;
/**
* @since 1.5
*/
private int connectTimeout;
private int readTimeout;
/**
* @since 1.6
*/
private MessageHeader requests;
/**
* @since 1.1
*/
private static volatile FileNameMap fileNameMap;
/**
* Loads filename map (a mimetable) from a data file. It will
* first try to load the user-specific table, defined
* by "content.types.user.table" property. If that fails,
* it tries to load the default built-in table.
*
* @return the FileNameMap
* @since 1.2
* @see #setFileNameMap(java.net.FileNameMap)
*/
public static FileNameMap getFileNameMap() {
FileNameMap map = fileNameMap;
if (map == null) {
fileNameMap = map = new FileNameMap() {
private final FileNameMap internalMap =
sun.net.www.MimeTable.getDefaultTable();
public String getContentTypeFor(String fileName) {
return internalMap.getContentTypeFor(fileName);
}
};
}
return map;
}
/**
* Sets the FileNameMap.
*
* @param map the FileNameMap to be set
* @see #getFileNameMap()
* @since 1.2
*/
public static void setFileNameMap(FileNameMap map) {
fileNameMap = map;
}
/**
* Opens a communications link to the resource referenced by this
* URL, if such a connection has not already been established.
* <p>
* If the {@code connect} method is called when the connection
* has already been opened (indicated by the {@code connected}
* field having the value {@code true}), the call is ignored.
* <p>
* URLConnection objects go through two phases: first they are
* created, then they are connected. After being created, and
* before being connected, various options can be specified
* (e.g., doInput and UseCaches). After connecting, it is an
* error to try to set them. Operations that depend on being
* connected, like getContentLength, will implicitly perform the
* connection, if necessary.
*
* @throws SocketTimeoutException if the timeout expires before
* the connection can be established
* @throws IOException if an I/O error occurs while opening the
* connection.
* @see java.net.URLConnection#connected
* @see #getConnectTimeout()
* @see #setConnectTimeout(int)
*/
public abstract void connect() throws IOException;
/**
* Sets a specified timeout value, in milliseconds, to be used
* when opening a communications link to the resource referenced
* by this URLConnection. If the timeout expires before the
* connection can be established, a
* java.net.SocketTimeoutException is raised. A timeout of zero is
* interpreted as an infinite timeout.
*
* <p> Some non-standard implementation of this method may ignore
* the specified timeout. To see the connect timeout set, please
* call getConnectTimeout().
*
* @param timeout an {@code int} that specifies the connect
* timeout value in milliseconds
* @throws IllegalArgumentException if the timeout parameter is negative
*
* @see #getConnectTimeout()
* @see #connect()
* @since 1.5
*/
public void setConnectTimeout(int timeout) {
if (timeout < 0) {
throw new IllegalArgumentException("timeout can not be negative");
}
connectTimeout = timeout;
}
/**
* Returns setting for connect timeout.
* <p>
* 0 return implies that the option is disabled
* (i.e., timeout of infinity).
*
* @return an {@code int} that indicates the connect timeout
* value in milliseconds
* @see #setConnectTimeout(int)
* @see #connect()
* @since 1.5
*/
public int getConnectTimeout() {
return connectTimeout;
}
/**
* Sets the read timeout to a specified timeout, in
* milliseconds. A non-zero value specifies the timeout when
* reading from Input stream when a connection is established to a
* resource. If the timeout expires before there is data available
* for read, a java.net.SocketTimeoutException is raised. A
* timeout of zero is interpreted as an infinite timeout.
*
* <p> Some non-standard implementation of this method ignores the
* specified timeout. To see the read timeout set, please call
* getReadTimeout().
*
* @param timeout an {@code int} that specifies the timeout
* value to be used in milliseconds
* @throws IllegalArgumentException if the timeout parameter is negative
*
* @see #getReadTimeout()
* @see InputStream#read()
* @since 1.5
*/
public void setReadTimeout(int timeout) {
if (timeout < 0) {
throw new IllegalArgumentException("timeout can not be negative");
}
readTimeout = timeout;
}
/**
* Returns setting for read timeout. 0 return implies that the
* option is disabled (i.e., timeout of infinity).
*
* @return an {@code int} that indicates the read timeout
* value in milliseconds
*
* @see #setReadTimeout(int)
* @see InputStream#read()
* @since 1.5
*/
public int getReadTimeout() {
return readTimeout;
}
/**
* Constructs a URL connection to the specified URL. A connection to
* the object referenced by the URL is not created.
*
* @param url the specified URL.
*/
protected URLConnection(URL url) {
this.url = url;
if (url == null) {
this.useCaches = defaultUseCaches;
} else {
this.useCaches = getDefaultUseCaches(url.getProtocol());
}
}
/**
* Returns the value of this {@code URLConnection}'s {@code URL}
* field.
*
* @return the value of this {@code URLConnection}'s {@code URL}
* field.
* @see java.net.URLConnection#url
*/
public URL getURL() {
return url;
}
/**
* Returns the value of the {@code content-length} header field.
* <P>
* <B>Note</B>: {@link #getContentLengthLong() getContentLengthLong()}
* should be preferred over this method, since it returns a {@code long}
* instead and is therefore more portable.</P>
*
* @return the content length of the resource that this connection's URL
* references, {@code -1} if the content length is not known,
* or if the content length is greater than Integer.MAX_VALUE.
*/
public int getContentLength() {
long l = getContentLengthLong();
if (l > Integer.MAX_VALUE)
return -1;
return (int) l;
}
/**
* Returns the value of the {@code content-length} header field as a
* long.
*
* @return the content length of the resource that this connection's URL
* references, or {@code -1} if the content length is
* not known.
* @since 1.7
*/
public long getContentLengthLong() {
return getHeaderFieldLong("content-length", -1);
}
/**
* Returns the value of the {@code content-type} header field.
*
* @return the content type of the resource that the URL references,
* or {@code null} if not known.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public String getContentType() {
return getHeaderField("content-type");
}
/**
* Returns the value of the {@code content-encoding} header field.
*
* @return the content encoding of the resource that the URL references,
* or {@code null} if not known.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public String getContentEncoding() {
return getHeaderField("content-encoding");
}
/**
* Returns the value of the {@code expires} header field.
*
* @return the expiration date of the resource that this URL references,
* or 0 if not known. The value is the number of milliseconds since
* January 1, 1970 GMT.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public long getExpiration() {
return getHeaderFieldDate("expires", 0);
}
/**
* Returns the value of the {@code date} header field.
*
* @return the sending date of the resource that the URL references,
* or {@code 0} if not known. The value returned is the
* number of milliseconds since January 1, 1970 GMT.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public long getDate() {
return getHeaderFieldDate("date", 0);
}
/**
* Returns the value of the {@code last-modified} header field.
* The result is the number of milliseconds since January 1, 1970 GMT.
*
* @return the date the resource referenced by this
* {@code URLConnection} was last modified, or 0 if not known.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public long getLastModified() {
return getHeaderFieldDate("last-modified", 0);
}
/**
* Returns the value of the named header field.
* <p>
* If called on a connection that sets the same header multiple times
* with possibly different values, only the last value is returned.
*
*
* @param name the name of a header field.
* @return the value of the named header field, or {@code null}
* if there is no such field in the header.
*/
public String getHeaderField(String name) {
return null;
}
/**
* Returns an unmodifiable Map of the header fields.
* The Map keys are Strings that represent the
* response-header field names. Each Map value is an
* unmodifiable List of Strings that represents
* the corresponding field values.
*
* This method is overridden by the subclasses of {@code URLConnection}.
*
* In the implementation of these methods, if a given key has multiple
* corresponding values, they must be returned in the order they were added,
* preserving the insertion-order.
*
* @implSpec The default implementation of this method returns an empty map always.
*
* @return a Map of header fields
* @since 1.4
*/
public Map<String,List<String>> getHeaderFields() {
return Collections.emptyMap();
}
/**
* Returns the value of the named field parsed as a number.
* <p>
* This form of {@code getHeaderField} exists because some
* connection types (e.g., {@code http-ng}) have pre-parsed
* headers. Classes for that connection type can override this method
* and short-circuit the parsing.
*
* @param name the name of the header field.
* @param defaultValue the default value.
* @return the value of the named field, parsed as an integer. The
* {@code defaultValue} value is returned if the field is
* missing or malformed.
*/
public int getHeaderFieldInt(String name, int defaultValue) {
final String value = getHeaderField(name);
if (value != null) {
try {
return Integer.parseInt(value);
} catch (NumberFormatException e) { }
}
return defaultValue;
}
/**
* Returns the value of the named field parsed as a number.
* <p>
* This form of {@code getHeaderField} exists because some
* connection types (e.g., {@code http-ng}) have pre-parsed
* headers. Classes for that connection type can override this method
* and short-circuit the parsing.
*
* @param name the name of the header field.
* @param defaultValue the default value.
* @return the value of the named field, parsed as a long. The
* {@code defaultValue} value is returned if the field is
* missing or malformed.
* @since 1.7
*/
public long getHeaderFieldLong(String name, long defaultValue) {
final String value = getHeaderField(name);
if (value != null) {
try {
return Long.parseLong(value);
} catch (NumberFormatException e) { }
}
return defaultValue;
}
/**
* Returns the value of the named field parsed as date.
* The result is the number of milliseconds since January 1, 1970 GMT
* represented by the named field.
* <p>
* This form of {@code getHeaderField} exists because some
* connection types (e.g., {@code http-ng}) have pre-parsed
* headers. Classes for that connection type can override this method
* and short-circuit the parsing.
*
* @param name the name of the header field.
* @param defaultValue a default value.
* @return the value of the field, parsed as a date. The value of the
* {@code defaultValue} argument is returned if the field is
* missing or malformed.
*/
@SuppressWarnings("deprecation")
public long getHeaderFieldDate(String name, long defaultValue) {
final String value = getHeaderField(name);
if (value != null) {
try {
return Date.parse(value);
} catch (Exception e) { }
}
return defaultValue;
}
/**
* 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, in which case, {@link #getHeaderField(int) getHeaderField(0)}
* may return some value, but {@code getHeaderFieldKey(0)} returns {@code null}.
* For {@code n > 0 } it returns {@code null} if there are fewer than {@code n+1} fields.
*
* @param n an index, where {@code n>=0}
* @return the key for the {@code n}<sup>th</sup> header field,
* or {@code null} if there are fewer than {@code n+1}
* fields when {@code n > 0}.
*/
public String getHeaderFieldKey(int n) {
return null;
}
/**
* Returns the value for the {@code n}<sup>th</sup> header field.
* It returns {@code null} if there are fewer than
* {@code n+1} fields.
* <p>
* This method can be used in conjunction with the
* {@link #getHeaderFieldKey(int) 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 there are fewer than {@code n+1} fields
* @see java.net.URLConnection#getHeaderFieldKey(int)
*/
public String getHeaderField(int n) {
return null;
}
/**
* Retrieves the contents of this URL connection.
* <p>
* This method first determines the content type of the object by
* calling the {@code getContentType} method. If this is
* the first time that the application has seen that specific content
* type, a content handler for that content type is created.
* <p> This is done as follows:
* <ol>
* <li>If the application has set up a content handler factory instance
* using the {@code setContentHandlerFactory} method, the
* {@code createContentHandler} method of that instance is called
* with the content type as an argument; the result is a content
* handler for that content type.
* <li>If no {@code ContentHandlerFactory} has yet been set up,
* or if the factory's {@code createContentHandler} method
* returns {@code null}, then the {@linkplain java.util.ServiceLoader
* ServiceLoader} mechanism is used to locate {@linkplain
* java.net.ContentHandlerFactory ContentHandlerFactory}
* implementations using the system class
* loader. The order that factories are located is implementation
* specific, and an implementation is free to cache the located
* factories. A {@linkplain java.util.ServiceConfigurationError
* ServiceConfigurationError}, {@code Error} or {@code RuntimeException}
* thrown from the {@code createContentHandler}, if encountered, will
* be propagated to the calling thread. The {@code
* createContentHandler} method of each factory, if instantiated, is
* invoked, with the content type, until a factory returns non-null,
* or all factories have been exhausted.
* <li>Failing that, this method tries to load a content handler
* class as defined by {@link java.net.ContentHandler ContentHandler}.
* If the class does not exist, or is not a subclass of {@code
* ContentHandler}, then an {@code UnknownServiceException} is thrown.
* </ol>
*
* @return the object fetched. The {@code instanceof} operator
* should be used to determine the specific kind of object
* returned.
* @throws IOException if an I/O error occurs while
* getting the content.
* @throws UnknownServiceException if the protocol does not support
* the content type.
* @see java.net.ContentHandlerFactory#createContentHandler(java.lang.String)
* @see java.net.URLConnection#getContentType()
* @see java.net.URLConnection#setContentHandlerFactory(java.net.ContentHandlerFactory)
*/
public Object getContent() throws IOException {
// Must call getInputStream before GetHeaderField gets called
// so that FileNotFoundException has a chance to be thrown up
// from here without being caught.
getInputStream();
return getContentHandler().getContent(this);
}
/**
* Retrieves the contents of this URL connection.
*
* @param classes the {@code Class} array
* indicating the requested types
* @return the object fetched that is the first match of the type
* specified in the classes array. null if none of
* the requested types are supported.
* The {@code instanceof} operator should be used to
* determine the specific kind of object returned.
* @throws IOException if an I/O error occurs while
* getting the content.
* @throws UnknownServiceException if the protocol does not support
* the content type.
* @see java.net.URLConnection#getContent()
* @see java.net.ContentHandlerFactory#createContentHandler(java.lang.String)
* @see java.net.URLConnection#getContent(java.lang.Class[])
* @see java.net.URLConnection#setContentHandlerFactory(java.net.ContentHandlerFactory)
* @since 1.3
*/
public Object getContent(Class<?>[] classes) throws IOException {
// Must call getInputStream before GetHeaderField gets called
// so that FileNotFoundException has a chance to be thrown up
// from here without being caught.
getInputStream();
return getContentHandler().getContent(this, classes);
}
/**
* Returns a permission object representing the permission
* necessary to make the connection represented by this
* object. This method returns null if no permission is
* required to make the connection. By default, this method
* returns {@code java.security.AllPermission}. Subclasses
* should override this method and return the permission
* that best represents the permission required to make
* a connection to the URL. For example, a {@code URLConnection}
* representing a {@code file:} URL would return a
* {@code java.io.FilePermission} object.
*
* <p>The permission returned may dependent upon the state of the
* connection. For example, the permission before connecting may be
* different from that after connecting. For example, an HTTP
* sever, say foo.com, may redirect the connection to a different
* host, say bar.com. Before connecting the permission returned by
* the connection will represent the permission needed to connect
* to foo.com, while the permission returned after connecting will
* be to bar.com.
*
* <p>Permissions are generally used for two purposes: to protect
* caches of objects obtained through URLConnections, and to check
* the right of a recipient to learn about a particular URL. In
* the first case, the permission should be obtained
* <em>after</em> the object has been obtained. For example, in an
* HTTP connection, this will represent the permission to connect
* to the host from which the data was ultimately fetched. In the
* second case, the permission should be obtained and tested
* <em>before</em> connecting.
*
* @return the permission object representing the permission
* necessary to make the connection represented by this
* URLConnection.
*
* @throws IOException if the computation of the permission
* requires network or file I/O and an exception occurs while
* computing it.
*
* @deprecated
* Permissions can no longer be used for controlling access to resources
* as the Security Manager is no longer supported.
*/
@Deprecated(since = "25", forRemoval = true)
public Permission getPermission() throws IOException {
return SecurityConstants.ALL_PERMISSION;
}
/**
* Returns an input stream that reads from this open connection.
*
* A SocketTimeoutException can be thrown when reading from the
* returned input stream if the read timeout expires before data
* is available for read.
*
* @apiNote The {@code InputStream} returned by this method can wrap an
* {@link java.util.zip.InflaterInputStream InflaterInputStream}, whose
* {@link java.util.zip.InflaterInputStream#read(byte[], int, int)
* read(byte[], int, int)} method can modify any element of the output
* buffer.
*
* @return an input stream that reads from this open connection.
* @throws IOException if an I/O error occurs while
* creating the input stream.
* @throws UnknownServiceException if the protocol does not support
* input.
* @see #setReadTimeout(int)
* @see #getReadTimeout()
*/
public InputStream getInputStream() throws IOException {
throw new UnknownServiceException("protocol doesn't support input");
}
/**
* Returns an output stream that writes to this connection.
*
* @return an output stream that writes to this connection.
* @throws IOException if an I/O error occurs while
* creating the output stream.
* @throws UnknownServiceException if the protocol does not support
* output.
*/
public OutputStream getOutputStream() throws IOException {
throw new UnknownServiceException("protocol doesn't support output");
}
/**
* Returns a {@code String} representation of this URL connection.
*
* @return a string representation of this {@code URLConnection}.
*/
public String toString() {
return this.getClass().getName() + ":" + url;
}
/**
* Sets the value of the {@code doInput} field for this
* {@code URLConnection} to the specified value.
* <p>
* A URL connection can be used for input and/or output. Set the doInput
* flag to true if you intend to use the URL connection for input,
* false if not. The default is true.
*
* @param doinput the new value.
* @throws IllegalStateException if already connected
* @see java.net.URLConnection#doInput
* @see #getDoInput()
*/
public void setDoInput(boolean doinput) {
checkConnected();
doInput = doinput;
}
/**
* Returns the value of this {@code URLConnection}'s
* {@code doInput} flag.
*
* @return the value of this {@code URLConnection}'s
* {@code doInput} flag.
* @see #setDoInput(boolean)
*/
public boolean getDoInput() {
return doInput;
}
/**
* Sets the value of the {@code doOutput} field for this
* {@code URLConnection} to the specified value.
* <p>
* A URL connection can be used for input and/or output. Set the doOutput
* flag to true if you intend to use the URL connection for output,
* false if not. The default is false.
*
* @param dooutput the new value.
* @throws IllegalStateException if already connected
* @see #getDoOutput()
*/
public void setDoOutput(boolean dooutput) {
checkConnected();
doOutput = dooutput;
}
/**
* Returns the value of this {@code URLConnection}'s
* {@code doOutput} flag.
*
* @return the value of this {@code URLConnection}'s
* {@code doOutput} flag.
* @see #setDoOutput(boolean)
*/
public boolean getDoOutput() {
return doOutput;
}
/**
* Set the value of the {@code allowUserInteraction} field of
* this {@code URLConnection}.
*
* @param allowuserinteraction the new value.
* @throws IllegalStateException if already connected
* @see #getAllowUserInteraction()
*/
public void setAllowUserInteraction(boolean allowuserinteraction) {
checkConnected();
allowUserInteraction = allowuserinteraction;
}
/**
* Returns the value of the {@code allowUserInteraction} field for
* this object.
*
* @return the value of the {@code allowUserInteraction} field for
* this object.
* @see #setAllowUserInteraction(boolean)
*/
public boolean getAllowUserInteraction() {
return allowUserInteraction;
}
/**
* Sets the default value of the
* {@code allowUserInteraction} field for all future
* {@code URLConnection} objects to the specified value.
*
* @param defaultallowuserinteraction the new value.
* @see #getDefaultAllowUserInteraction()
*/
public static void setDefaultAllowUserInteraction(boolean defaultallowuserinteraction) {
defaultAllowUserInteraction = defaultallowuserinteraction;
}
/**
* Returns the default value of the {@code allowUserInteraction}
* field.
* <p>
* This default is "sticky", being a part of the static state of all
* URLConnections. This flag applies to the next, and all following
* URLConnections that are created.
*
* @return the default value of the {@code allowUserInteraction}
* field.
* @see #setDefaultAllowUserInteraction(boolean)
*/
public static boolean getDefaultAllowUserInteraction() {
return defaultAllowUserInteraction;
}
/**
* Sets the value of the {@code useCaches} field of this
* {@code URLConnection} to the specified value.
* <p>
* Some protocols do caching of documents. Occasionally, it is important
* to be able to "tunnel through" and ignore the caches (e.g., the
* "reload" button in a browser). If the UseCaches flag on a connection