| {@code openConnection()} | *{@code connect()} |
|---|---|
| Manipulate parameters that affect the connection to the remote * resource. | *Interact with the resource; query header fields and * contents. |
* The setup parameters are modified using the following methods: *
* and the general request properties are modified using the method: *
* Default values for the {@code AllowUserInteraction} and * {@code UseCaches} parameters can be set using the methods * {@code setDefaultAllowUserInteraction} and * {@code setDefaultUseCaches}. *
* 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. *
* The following methods are used to access the header fields and * the contents after the connection is made to the remote object: *
* Certain header fields are accessed frequently. The methods: *
* 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. *
* 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. *
* More information on the request properties and header fields of * an {@code http} connection can be found at: *
* * 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. * * @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. ** http://www.ietf.org/rfc/rfc2616.txt *
* The value of this field can be accessed by the * {@code getURL} method. *
* 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. *
* 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. *
* 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. *
* 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. *
* 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. *
* 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 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. *
* This field is set by the {@code setUseCaches} method. Its * value is returned by the {@code getUseCaches} method. *
* Its default value is the value given in the last invocation of the * {@code setDefaultUseCaches} method. * * @see java.net.URLConnection#setUseCaches(boolean) * @see java.net.URLConnection#getUseCaches() * @see java.net.URLConnection#setDefaultUseCaches(boolean) */ protected boolean useCaches = defaultUseCaches; /** * Some protocols support skipping the fetching of the object unless * the object has been modified more recently than a certain time. *
* 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. *
* This variable is set by the {@code setIfModifiedSince} * method. Its value is returned by the * {@code getIfModifiedSince} method. *
* 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 FileNameMap fileNameMap; /** * @since 1.2.2 */ private static boolean fileNameMapLoaded = false; /** * 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 synchronized FileNameMap getFileNameMap() { if ((fileNameMap == null) && !fileNameMapLoaded) { fileNameMap = sun.net.www.MimeTable.loadTable(); fileNameMapLoaded = true; } return new FileNameMap() { private FileNameMap map = fileNameMap; public String getContentTypeFor(String fileName) { return map.getContentTypeFor(fileName); } }; } /** * Sets the FileNameMap. *
* 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 map the FileNameMap to be set * @exception SecurityException if a security manager exists and its * {@code checkSetFactory} method doesn't allow the operation. * @see SecurityManager#checkSetFactory * @see #getFileNameMap() * @since 1.2 */ public static void setFileNameMap(FileNameMap map) { SecurityManager sm = System.getSecurityManager(); if (sm != null) sm.checkSetFactory(); fileNameMap = map; } /** * Opens a communications link to the resource referenced by this * URL, if such a connection has not already been established. *
* 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. *
* 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 * @exception IOException if an I/O error occurs while opening the * connection. * @see java.net.URLConnection#connected * @see #getConnectTimeout() * @see #setConnectTimeout(int) */ abstract public 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. *
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. *
* 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. * *
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; } /** * 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. *
* Note: {@link #getContentLengthLong() getContentLengthLong()} * should be preferred over this method, since it returns a {@code long} * instead and is therefore more portable.
* * @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. *
* 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.
*
* @return a Map of header fields
* @since 1.4
*/
public Map
* 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 Default the default value.
* @return the value of the named field, parsed as an integer. The
* {@code Default} value is returned if the field is
* missing or malformed.
*/
public int getHeaderFieldInt(String name, int Default) {
String value = getHeaderField(name);
try {
return Integer.parseInt(value);
} catch (Exception e) { }
return Default;
}
/**
* Returns the value of the named field parsed as a number.
*
* 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 Default the default value.
* @return the value of the named field, parsed as a long. The
* {@code Default} value is returned if the field is
* missing or malformed.
* @since 1.7
*/
public long getHeaderFieldLong(String name, long Default) {
String value = getHeaderField(name);
try {
return Long.parseLong(value);
} catch (Exception e) { }
return Default;
}
/**
* 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.
*
* 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 Default a default value.
* @return the value of the field, parsed as a date. The value of the
* {@code Default} argument is returned if the field is
* missing or malformed.
*/
@SuppressWarnings("deprecation")
public long getHeaderFieldDate(String name, long Default) {
String value = getHeaderField(name);
try {
return Date.parse(value);
} catch (Exception e) { }
return Default;
}
/**
* Returns the key for the {@code n}th header field.
* 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}th header field,
* or {@code null} if there are fewer than {@code n+1}
* fields.
*/
public String getHeaderFieldKey(int n) {
return null;
}
/**
* Returns the value for the {@code n}th header field.
* It returns {@code null} if there are fewer than
* {@code n+1}fields.
*
* 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}th 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.
*
* 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:
* 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.
*
* 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
* after 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
* before connecting.
*
* @return the permission object representing the permission
* necessary to make the connection represented by this
* URLConnection.
*
* @exception IOException if the computation of the permission
* requires network or file I/O and an exception occurs while
* computing it.
*/
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.
*
* @return an input stream that reads from this open connection.
* @exception IOException if an I/O error occurs while
* creating the input stream.
* @exception 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.
* @exception IOException if an I/O error occurs while
* creating the output stream.
* @exception 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.
*
* 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) {
if (connected)
throw new IllegalStateException("Already connected");
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.
*
* 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) {
if (connected)
throw new IllegalStateException("Already connected");
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) {
if (connected)
throw new IllegalStateException("Already connected");
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.
*
* Ths 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.
*
* 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
* is true, the connection is allowed to use whatever caches it can.
* If false, caches are to be ignored.
* The default value comes from DefaultUseCaches, which defaults to
* true.
*
* @param usecaches a {@code boolean} indicating whether
* or not to allow caching
* @throws IllegalStateException if already connected
* @see #getUseCaches()
*/
public void setUseCaches(boolean usecaches) {
if (connected)
throw new IllegalStateException("Already connected");
useCaches = usecaches;
}
/**
* Returns the value of this {@code URLConnection}'s
* {@code useCaches} field.
*
* @return the value of this {@code URLConnection}'s
* {@code useCaches} field.
* @see #setUseCaches(boolean)
*/
public boolean getUseCaches() {
return useCaches;
}
/**
* Sets the value of the {@code ifModifiedSince} field of
* this {@code URLConnection} to the specified value.
*
* @param ifmodifiedsince the new value.
* @throws IllegalStateException if already connected
* @see #getIfModifiedSince()
*/
public void setIfModifiedSince(long ifmodifiedsince) {
if (connected)
throw new IllegalStateException("Already connected");
ifModifiedSince = ifmodifiedsince;
}
/**
* Returns the value of this object's {@code ifModifiedSince} field.
*
* @return the value of this object's {@code ifModifiedSince} field.
* @see #setIfModifiedSince(long)
*/
public long getIfModifiedSince() {
return ifModifiedSince;
}
/**
* Returns the default value of a {@code URLConnection}'s
* {@code useCaches} flag.
*
* Ths 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 a {@code URLConnection}'s
* {@code useCaches} flag.
* @see #setDefaultUseCaches(boolean)
*/
public boolean getDefaultUseCaches() {
return defaultUseCaches;
}
/**
* Sets the default value of the {@code useCaches} field to the
* specified value.
*
* @param defaultusecaches the new value.
* @see #getDefaultUseCaches()
*/
public void setDefaultUseCaches(boolean defaultusecaches) {
defaultUseCaches = defaultusecaches;
}
/**
* Sets the general request property. If a property with the key already
* exists, overwrite its value with the new value.
*
* NOTE: HTTP requires all request properties which can
* legally have multiple instances with the same key
* to use a comma-separated list syntax which enables multiple
* properties to be appended into a single property.
*
* @param key the keyword by which the request is known
* (e.g., "{@code Accept}").
* @param value the value associated with it.
* @throws IllegalStateException if already connected
* @throws NullPointerException if key is
* The {@code ContentHandlerFactory} instance is used to
* construct a content handler from a content type
*
* 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 fac the desired factory.
* @exception Error if the factory has already been defined.
* @exception SecurityException if a security manager exists and its
* {@code checkSetFactory} method doesn't allow the operation.
* @see java.net.ContentHandlerFactory
* @see java.net.URLConnection#getContent()
* @see SecurityManager#checkSetFactory
*/
public static synchronized void setContentHandlerFactory(ContentHandlerFactory fac) {
if (factory != null) {
throw new Error("factory already defined");
}
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkSetFactory();
}
factory = fac;
}
private static Hashtable
* Ideally, this routine would not be needed. But many
* {@code http} servers return the incorrect content type; in
* addition, there are many nonstandard extensions. Direct inspection
* of the bytes to determine the content type is often more accurate
* than believing the content type claimed by the {@code http} server.
*
* @param is an input stream that supports marks.
* @return a guess at the content type, or {@code null} if none
* can be determined.
* @exception IOException if an I/O error occurs while reading the
* input stream.
* @see java.io.InputStream#mark(int)
* @see java.io.InputStream#markSupported()
* @see java.net.URLConnection#getContentType()
*/
static public String guessContentTypeFromStream(InputStream is)
throws IOException {
// If we can't read ahead safely, just give up on guessing
if (!is.markSupported())
return null;
is.mark(16);
int c1 = is.read();
int c2 = is.read();
int c3 = is.read();
int c4 = is.read();
int c5 = is.read();
int c6 = is.read();
int c7 = is.read();
int c8 = is.read();
int c9 = is.read();
int c10 = is.read();
int c11 = is.read();
int c12 = is.read();
int c13 = is.read();
int c14 = is.read();
int c15 = is.read();
int c16 = is.read();
is.reset();
if (c1 == 0xCA && c2 == 0xFE && c3 == 0xBA && c4 == 0xBE) {
return "application/java-vm";
}
if (c1 == 0xAC && c2 == 0xED) {
// next two bytes are version number, currently 0x00 0x05
return "application/x-java-serialized-object";
}
if (c1 == '<') {
if (c2 == '!'
|| ((c2 == 'h' && (c3 == 't' && c4 == 'm' && c5 == 'l' ||
c3 == 'e' && c4 == 'a' && c5 == 'd') ||
(c2 == 'b' && c3 == 'o' && c4 == 'd' && c5 == 'y'))) ||
((c2 == 'H' && (c3 == 'T' && c4 == 'M' && c5 == 'L' ||
c3 == 'E' && c4 == 'A' && c5 == 'D') ||
(c2 == 'B' && c3 == 'O' && c4 == 'D' && c5 == 'Y')))) {
return "text/html";
}
if (c2 == '?' && c3 == 'x' && c4 == 'm' && c5 == 'l' && c6 == ' ') {
return "application/xml";
}
}
// big and little (identical) endian UTF-8 encodings, with BOM
if (c1 == 0xef && c2 == 0xbb && c3 == 0xbf) {
if (c4 == '<' && c5 == '?' && c6 == 'x') {
return "application/xml";
}
}
// big and little endian UTF-16 encodings, with byte order mark
if (c1 == 0xfe && c2 == 0xff) {
if (c3 == 0 && c4 == '<' && c5 == 0 && c6 == '?' &&
c7 == 0 && c8 == 'x') {
return "application/xml";
}
}
if (c1 == 0xff && c2 == 0xfe) {
if (c3 == '<' && c4 == 0 && c5 == '?' && c6 == 0 &&
c7 == 'x' && c8 == 0) {
return "application/xml";
}
}
// big and little endian UTF-32 encodings, with BOM
if (c1 == 0x00 && c2 == 0x00 && c3 == 0xfe && c4 == 0xff) {
if (c5 == 0 && c6 == 0 && c7 == 0 && c8 == '<' &&
c9 == 0 && c10 == 0 && c11 == 0 && c12 == '?' &&
c13 == 0 && c14 == 0 && c15 == 0 && c16 == 'x') {
return "application/xml";
}
}
if (c1 == 0xff && c2 == 0xfe && c3 == 0x00 && c4 == 0x00) {
if (c5 == '<' && c6 == 0 && c7 == 0 && c8 == 0 &&
c9 == '?' && c10 == 0 && c11 == 0 && c12 == 0 &&
c13 == 'x' && c14 == 0 && c15 == 0 && c16 == 0) {
return "application/xml";
}
}
if (c1 == 'G' && c2 == 'I' && c3 == 'F' && c4 == '8') {
return "image/gif";
}
if (c1 == '#' && c2 == 'd' && c3 == 'e' && c4 == 'f') {
return "image/x-bitmap";
}
if (c1 == '!' && c2 == ' ' && c3 == 'X' && c4 == 'P' &&
c5 == 'M' && c6 == '2') {
return "image/x-pixmap";
}
if (c1 == 137 && c2 == 80 && c3 == 78 &&
c4 == 71 && c5 == 13 && c6 == 10 &&
c7 == 26 && c8 == 10) {
return "image/png";
}
if (c1 == 0xFF && c2 == 0xD8 && c3 == 0xFF) {
if (c4 == 0xE0) {
return "image/jpeg";
}
/**
* File format used by digital cameras to store images.
* Exif Format can be read by any application supporting
* JPEG. Exif Spec can be found at:
* http://www.pima.net/standards/it10/PIMA15740/Exif_2-1.PDF
*/
if ((c4 == 0xE1) &&
(c7 == 'E' && c8 == 'x' && c9 == 'i' && c10 =='f' &&
c11 == 0)) {
return "image/jpeg";
}
if (c4 == 0xEE) {
return "image/jpg";
}
}
if (c1 == 0xD0 && c2 == 0xCF && c3 == 0x11 && c4 == 0xE0 &&
c5 == 0xA1 && c6 == 0xB1 && c7 == 0x1A && c8 == 0xE1) {
/* Above is signature of Microsoft Structured Storage.
* Below this, could have tests for various SS entities.
* For now, just test for FlashPix.
*/
if (checkfpx(is)) {
return "image/vnd.fpx";
}
}
if (c1 == 0x2E && c2 == 0x73 && c3 == 0x6E && c4 == 0x64) {
return "audio/basic"; // .au format, big endian
}
if (c1 == 0x64 && c2 == 0x6E && c3 == 0x73 && c4 == 0x2E) {
return "audio/basic"; // .au format, little endian
}
if (c1 == 'R' && c2 == 'I' && c3 == 'F' && c4 == 'F') {
/* I don't know if this is official but evidence
* suggests that .wav files start with "RIFF" - brown
*/
return "audio/x-wav";
}
return null;
}
/**
* Check for FlashPix image data in InputStream is. Return true if
* the stream has FlashPix data, false otherwise. Before calling this
* method, the stream should have already been checked to be sure it
* contains Microsoft Structured Storage data.
*/
static private boolean checkfpx(InputStream is) throws IOException {
/* Test for FlashPix image data in Microsoft Structured Storage format.
* In general, should do this with calls to an SS implementation.
* Lacking that, need to dig via offsets to get to the FlashPix
* ClassID. Details:
*
* Offset to Fpx ClsID from beginning of stream should be:
*
* FpxClsidOffset = rootEntryOffset + clsidOffset
*
* where: clsidOffset = 0x50.
* rootEntryOffset = headerSize + sectorSize*sectDirStart
* + 128*rootEntryDirectory
*
* where: headerSize = 0x200 (always)
* sectorSize = 2 raised to power of uSectorShift,
* which is found in the header at
* offset 0x1E.
* sectDirStart = found in the header at offset 0x30.
* rootEntryDirectory = in general, should search for
* directory labelled as root.
* We will assume value of 0 (i.e.,
* rootEntry is in first directory)
*/
// Mark the stream so we can reset it. 0x100 is enough for the first
// few reads, but the mark will have to be reset and set again once
// the offset to the root directory entry is computed. That offset
// can be very large and isn't know until the stream has been read from
is.mark(0x100);
// Get the byte ordering located at 0x1E. 0xFE is Intel,
// 0xFF is other
long toSkip = (long)0x1C;
long posn;
if ((posn = skipForward(is, toSkip)) < toSkip) {
is.reset();
return false;
}
int c[] = new int[16];
if (readBytes(c, 2, is) < 0) {
is.reset();
return false;
}
int byteOrder = c[0];
posn+=2;
int uSectorShift;
if (readBytes(c, 2, is) < 0) {
is.reset();
return false;
}
if(byteOrder == 0xFE) {
uSectorShift = c[0];
uSectorShift += c[1] << 8;
}
else {
uSectorShift = c[0] << 8;
uSectorShift += c[1];
}
posn += 2;
toSkip = (long)0x30 - posn;
long skipped = 0;
if ((skipped = skipForward(is, toSkip)) < toSkip) {
is.reset();
return false;
}
posn += skipped;
if (readBytes(c, 4, is) < 0) {
is.reset();
return false;
}
int sectDirStart;
if(byteOrder == 0xFE) {
sectDirStart = c[0];
sectDirStart += c[1] << 8;
sectDirStart += c[2] << 16;
sectDirStart += c[3] << 24;
} else {
sectDirStart = c[0] << 24;
sectDirStart += c[1] << 16;
sectDirStart += c[2] << 8;
sectDirStart += c[3];
}
posn += 4;
is.reset(); // Reset back to the beginning
toSkip = 0x200L + (long)(1<
*
*
* @return the object fetched. The {@code instanceof} operator
* should be used to determine the specific kind of object
* returned.
* @exception IOException if an I/O error occurs while
* getting the content.
* @exception 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.
* @exception IOException if an I/O error occurs while
* getting the content.
* @exception 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
* a connection to the URL. For example, a {@code URLConnection}
* representing a {@code file:} URL would return a
* {@code java.io.FilePermission} object.
*
* null
* @see #getRequestProperty(java.lang.String)
*/
public void setRequestProperty(String key, String value) {
if (connected)
throw new IllegalStateException("Already connected");
if (key == null)
throw new NullPointerException ("key is null");
if (requests == null)
requests = new MessageHeader();
requests.set(key, value);
}
/**
* Adds a general request property specified by a
* key-value pair. This method will not overwrite
* existing values associated with the same key.
*
* @param key the keyword by which the request is known
* (e.g., "{@code Accept}").
* @param value the value associated with it.
* @throws IllegalStateException if already connected
* @throws NullPointerException if key is null
* @see #getRequestProperties()
* @since 1.4
*/
public void addRequestProperty(String key, String value) {
if (connected)
throw new IllegalStateException("Already connected");
if (key == null)
throw new NullPointerException ("key is null");
if (requests == null)
requests = new MessageHeader();
requests.add(key, value);
}
/**
* Returns the value of the named general request property for this
* connection.
*
* @param key the keyword by which the request is known (e.g., "Accept").
* @return the value of the named general request property for this
* connection. If key is null, then null is returned.
* @throws IllegalStateException if already connected
* @see #setRequestProperty(java.lang.String, java.lang.String)
*/
public String getRequestProperty(String key) {
if (connected)
throw new IllegalStateException("Already connected");
if (requests == null)
return null;
return requests.findValue(key);
}
/**
* Returns an unmodifiable Map of general request
* properties for this connection. The Map keys
* are Strings that represent the request-header
* field names. Each Map value is a unmodifiable List
* of Strings that represents the corresponding
* field values.
*
* @return a Map of the general request properties for this connection.
* @throws IllegalStateException if already connected
* @since 1.4
*/
public Map
* {package-prefix}.{major}.{minor}
* e.g.
* YoyoDyne.experimental.text.plain
*
*/
private ContentHandler lookupContentHandlerClassFor(String contentType)
throws InstantiationException, IllegalAccessException, ClassNotFoundException {
String contentHandlerClassName = typeToPackageName(contentType);
String contentHandlerPkgPrefixes =getContentHandlerPkgPrefixes();
StringTokenizer packagePrefixIter =
new StringTokenizer(contentHandlerPkgPrefixes, "|");
while (packagePrefixIter.hasMoreTokens()) {
String packagePrefix = packagePrefixIter.nextToken().trim();
try {
String clsName = packagePrefix + "." + contentHandlerClassName;
Class cls = null;
try {
cls = Class.forName(clsName);
} catch (ClassNotFoundException e) {
ClassLoader cl = ClassLoader.getSystemClassLoader();
if (cl != null) {
cls = cl.loadClass(clsName);
}
}
if (cls != null) {
ContentHandler handler =
(ContentHandler)cls.newInstance();
return handler;
}
} catch(Exception e) {
}
}
return UnknownContentHandler.INSTANCE;
}
/**
* Utility function to map a MIME content type into an equivalent
* pair of class name components. For example: "text/html" would
* be returned as "text.html"
*/
private String typeToPackageName(String contentType) {
// make sure we canonicalize the class name: all lower case
contentType = contentType.toLowerCase();
int len = contentType.length();
char nm[] = new char[len];
contentType.getChars(0, len, nm, 0);
for (int i = 0; i < len; i++) {
char c = nm[i];
if (c == '/') {
nm[i] = '.';
} else if (!('A' <= c && c <= 'Z' ||
'a' <= c && c <= 'z' ||
'0' <= c && c <= '9')) {
nm[i] = '_';
}
}
return new String(nm);
}
/**
* Returns a vertical bar separated list of package prefixes for potential
* content handlers. Tries to get the java.content.handler.pkgs property
* to use as a set of package prefixes to search. Whether or not
* that property has been defined, the sun.net.www.content is always
* the last one on the returned package list.
*/
private String getContentHandlerPkgPrefixes() {
String packagePrefixList = AccessController.doPrivileged(
new sun.security.action.GetPropertyAction(contentPathProp, ""));
if (packagePrefixList != "") {
packagePrefixList += "|";
}
return packagePrefixList + contentClassPrefix;
}
/**
* Tries to determine the content type of an object, based
* on the specified "file" component of a URL.
* This is a convenience method that can be used by
* subclasses that override the {@code getContentType} method.
*
* @param fname a filename.
* @return a guess as to what the content type of the object is,
* based upon its file name.
* @see java.net.URLConnection#getContentType()
*/
public static String guessContentTypeFromName(String fname) {
return getFileNameMap().getContentTypeFor(fname);
}
/**
* Tries to determine the type of an input stream based on the
* characters at the beginning of the input stream. This method can
* be used by subclasses that override the
* {@code getContentType} method.
*