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. In
* general, creating a connection to a URL is a multistep process:
* *
openConnection() |
* connect() |
|---|---|
| Manipulate parameters that affect the connection to the remote * resource. | *Interact with the resource; query header fields and * contents. |
openConnection method on a URL.
* connect method.
* * The setup parameters are modified using the following methods: *
setAllowUserInteraction
* setDoInput
* setDoOutput
* setIfModifiedSince
* setUseCaches
* * and the general request properties are modified using the method: *
setRequestProperty
*
* Default values for the AllowUserInteraction and
* UseCaches parameters can be set using the methods
* setDefaultAllowUserInteraction and
* setDefaultUseCaches.
*
* Each of the above set methods has a corresponding
* 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: *
getContent
* getHeaderField
* getInputStream
* getOutputStream
* * Certain header fields are accessed frequently. The methods: *
getContentEncoding
* getContentLength
* getContentType
* getDate
* getExpiration
* getLastModifed
*
* provide convenient access to these fields. The
* getContentType method is used by the
* getContent method to determine the type of the remote
* object; subclasses may find it convenient to override the
* 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: getInputStream and getContent,
* which are mirrored in the URL class by convenience methods.
*
* More information on the request properties and header fields of
* an http connection can be found at:
*
* * Note about* http://www.ietf.org/rfc/rfc2616.txt *
fileNameMap: In versions prior to JDK 1.1.6,
* field fileNameMap of URLConnection was public.
* In JDK 1.1.6 and later, fileNameMap is private; accessor
* and mutator methods {@link #getFileNameMap() getFileNameMap} and
* {@link #setFileNameMap(java.net.FileNameMap) setFileNameMap} are added
* to access it. This change is also described on the
* Compatibility page.
*
* Invoking the close() methods on the InputStream or OutputStream of an
* 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 JDK1.0
*/
public abstract class URLConnection {
/**
* The URL represents the remote object on the World Wide Web to
* which this connection is opened.
*
* The value of this field can be accessed by the
* getURL method.
*
* The default value of this variable is the value of the URL
* argument in the URLConnection constructor.
*
* @see java.net.URLConnection#getURL()
* @see java.net.URLConnection#url
*/
protected URL url;
/**
* This variable is set by the setDoInput method. Its
* value is returned by the getDoInput method.
*
* A URL connection can be used for input and/or output. Setting the
* doInput flag to true indicates that
* the application intends to read data from the URL connection.
*
* The default value of this field is true.
*
* @see java.net.URLConnection#getDoInput()
* @see java.net.URLConnection#setDoInput(boolean)
*/
protected boolean doInput = true;
/**
* This variable is set by the setDoOutput method. Its
* value is returned by the getDoOutput method.
*
* A URL connection can be used for input and/or output. Setting the
* doOutput flag to true indicates
* that the application intends to write data to the URL connection.
*
* The default value of this field is false.
*
* @see java.net.URLConnection#getDoOutput()
* @see java.net.URLConnection#setDoOutput(boolean)
*/
protected boolean doOutput = false;
private static boolean defaultAllowUserInteraction = false;
/**
* If true, this URL is being examined in
* a context in which it makes sense to allow user interactions such
* as popping up an authentication dialog. If false,
* then no user interaction is allowed.
*
* The value of this field can be set by the
* setAllowUserInteraction method.
* Its value is returned by the
* getAllowUserInteraction method.
* Its default value is the value of the argument in the last invocation
* of the 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 true, the protocol is allowed to use caching
* whenever it can. If false, the protocol must always
* try to get a fresh copy of the object.
*
* This field is set by the setUseCaches method. Its
* value is returned by the getUseCaches method.
*
* Its default value is the value given in the last invocation of the
* 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 setIfModifiedSince
* method. Its value is returned by the
* getIfModifiedSince method.
*
* The default value of this field is 0, indicating
* that the fetching must always occur.
*
* @see java.net.URLConnection#getIfModifiedSince()
* @see java.net.URLConnection#setIfModifiedSince(long)
*/
protected long ifModifiedSince = 0;
/**
* If false, this connection object has not created a
* communications link to the specified URL. If 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 JDK1.1
*/
private static 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 at
* lib/content-types.properties under java home.
*
* @return the FileNameMap
* @since 1.2
* @see #setFileNameMap(java.net.FileNameMap)
*/
public static synchronized FileNameMap getFileNameMap() {
if (fileNameMap == null) {
fileNameMap = new DefaultFileNameMap();
}
return fileNameMap;
}
/**
* Sets the FileNameMap.
*
* If there is a security manager, this method first calls
* the security manager's 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
* 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 connect method is called when the connection
* has already been opened (indicated by the connected
* field having the value 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 implmentation of this method may ignore
* the specified timeout. To see the connect timeout set, please
* call getConnectTimeout().
*
* @param timeout an 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 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 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 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 URLConnection's URL
* field.
*
* @return the value of this URLConnection's URL
* field.
* @see java.net.URLConnection#url
*/
public URL getURL() {
return url;
}
/**
* Returns the value of the 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 thecontent-length header field as a
* long.
*
* @return the content length of the resource that this connection's URL
* references, or -1 if the content length is
* not known.
* @since 7.0
*/
public long getContentLengthLong() {
return getHeaderFieldLong("content-length", -1);
}
/**
* Returns the value of the content-type header field.
*
* @return the content type of the resource that the URL references,
* or null if not known.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public String getContentType() {
return getHeaderField("content-type");
}
/**
* Returns the value of the content-encoding header field.
*
* @return the content encoding of the resource that the URL references,
* or null if not known.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public String getContentEncoding() {
return getHeaderField("content-encoding");
}
/**
* Returns the value of the 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 date header field.
*
* @return the sending date of the resource that the URL references,
* or 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 last-modified header field.
* The result is the number of milliseconds since January 1, 1970 GMT.
*
* @return the date the resource referenced by this
* 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
* This form of
* This form of
* This form of
* 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 n>=0
* @return the value of the
* This method first determines the content type of the object by
* calling the 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
* 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
* 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
* 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
* 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
* 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 NOTE: HTTP requires all request properties which can
* legally have multiple instances with the same key
* to use a comma-seperated 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., "
* The
* If there is a security manager, this method first calls
* the security manager's
* Ideally, this routine would not be needed. But many
* 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 MapgetHeaderField exists because some
* connection types (e.g., 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
* 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.
* getHeaderField exists because some
* connection types (e.g., 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
* Default value is returned if the field is
* missing or malformed.
* @since 7.0
*/
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.
* getHeaderField exists because some
* connection types (e.g., 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
* Default argument is returned if the field is
* missing or malformed.
*/
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 nth header field.
* It returns null if there are fewer than n+1 fields.
*
* @param n an index, where n>=0
* @return the key for the nth header field,
* or null if there are fewer than n+1
* fields.
*/
public String getHeaderFieldKey(int n) {
return null;
}
/**
* Returns the value for the nth header field.
* It returns null if there are fewer than
* n+1fields.
* nth header field
* or null if there are fewer than n+1 fields
* @see java.net.URLConnection#getHeaderFieldKey(int)
*/
public String getHeaderField(int n) {
return null;
}
/**
* Retrieves the contents of this URL connection.
* 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:
*
*
*
* @return the object fetched. The setContentHandlerFactory method, the
* createContentHandler method of that instance is called
* with the content type as an argument; the result is a content
* handler for that content type.
* createContentHandler method returns
* null, then the application loads the class named:
*
* where <contentType> is formed by taking the
* content-type string, replacing all slash characters with a
*
* sun.net.www.content.<contentType>
* period ('.'), and all other non-alphanumeric characters
* with the underscore character '_'. The alphanumeric
* characters are specifically the 26 uppercase ASCII letters
* 'A' through 'Z', the 26 lowercase ASCII
* letters 'a' through 'z', and the 10 ASCII
* digits '0' through '9'. If the specified
* class does not exist, or is not a subclass of
* ContentHandler, then an
* UnknownServiceException is thrown.
* 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 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 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 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 URLConnection
* representing a file: URL would return a
* java.io.FilePermission object.
*
* String representation of this URL connection.
*
* @return a string representation of this URLConnection.
*/
public String toString() {
return this.getClass().getName() + ":" + url;
}
/**
* Sets the value of the doInput field for this
* URLConnection to the specified value.
* URLConnection's
* doInput flag.
*
* @return the value of this URLConnection's
* doInput flag.
* @see #setDoInput(boolean)
*/
public boolean getDoInput() {
return doInput;
}
/**
* Sets the value of the doOutput field for this
* URLConnection to the specified value.
* URLConnection's
* doOutput flag.
*
* @return the value of this URLConnection's
* doOutput flag.
* @see #setDoOutput(boolean)
*/
public boolean getDoOutput() {
return doOutput;
}
/**
* Set the value of the allowUserInteraction field of
* this 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 allowUserInteraction field for
* this object.
*
* @return the value of the allowUserInteraction field for
* this object.
* @see #setAllowUserInteraction(boolean)
*/
public boolean getAllowUserInteraction() {
return allowUserInteraction;
}
/**
* Sets the default value of the
* allowUserInteraction field for all future
* 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 allowUserInteraction
* field.
* allowUserInteraction
* field.
* @see #setDefaultAllowUserInteraction(boolean)
*/
public static boolean getDefaultAllowUserInteraction() {
return defaultAllowUserInteraction;
}
/**
* Sets the value of the useCaches field of this
* URLConnection to the specified value.
* 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 URLConnection's
* useCaches field.
*
* @return the value of this URLConnection's
* useCaches field.
* @see #setUseCaches(boolean)
*/
public boolean getUseCaches() {
return useCaches;
}
/**
* Sets the value of the ifModifiedSince field of
* this 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 ifModifiedSince field.
*
* @return the value of this object's ifModifiedSince field.
* @see #setIfModifiedSince(long)
*/
public long getIfModifiedSince() {
return ifModifiedSince;
}
/**
* Returns the default value of a URLConnection's
* useCaches flag.
* URLConnection's
* useCaches flag.
* @see #setDefaultUseCaches(boolean)
*/
public boolean getDefaultUseCaches() {
return defaultUseCaches;
}
/**
* Sets the default value of the 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.
*
* Accept").
* @param value the value associated with it.
* @throws IllegalStateException if already connected
* @throws NullPointerException if key is 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., "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 MapURLConnection is created, it is initialized with
* these properties.
*
* @param key the keyword by which the request is known
* (e.g., "Accept").
* @param value the value associated with the key.
*
* @see java.net.URLConnection#setRequestProperty(java.lang.String,java.lang.String)
*
* @deprecated The instance specific setRequestProperty method
* should be used after an appropriate instance of URLConnection
* is obtained. Invoking this method will have no effect.
*
* @see #getDefaultRequestProperty(java.lang.String)
*/
@Deprecated
public static void setDefaultRequestProperty(String key, String value) {
}
/**
* Returns the value of the default request property. Default request
* properties are set for every connection.
*
* @param key the keyword by which the request is known (e.g., "Accept").
* @return the value of the default request property
* for the specified key.
*
* @see java.net.URLConnection#getRequestProperty(java.lang.String)
*
* @deprecated The instance specific getRequestProperty method
* should be used after an appropriate instance of URLConnection
* is obtained.
*
* @see #setDefaultRequestProperty(java.lang.String, java.lang.String)
*/
@Deprecated
public static String getDefaultRequestProperty(String key) {
return null;
}
/**
* The ContentHandler factory.
*/
static ContentHandlerFactory factory;
/**
* Sets the ContentHandlerFactory of an
* application. It can be called at most once by an application.
* ContentHandlerFactory instance is used to
* construct a content handler from a content type
* 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
* 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 handlers = new Hashtable();
/**
* Gets the Content Handler appropriate for this connection.
* @param connection the connection to use.
*/
synchronized ContentHandler getContentHandler()
throws IOException
{
String contentType = stripOffParameters(getContentType());
ContentHandler handler = null;
if (contentType == null) {
if ((contentType = guessContentTypeFromName(url.getFile())) == null) {
contentType = guessContentTypeFromStream(getInputStream());
}
}
if (contentType == null) {
return UnknownContentHandler.INSTANCE;
}
try {
handler = (ContentHandler) handlers.get(contentType);
if (handler != null)
return handler;
} catch(Exception e) {
}
if (factory != null)
handler = factory.createContentHandler(contentType);
if (handler == null) {
try {
handler = lookupContentHandlerClassFor(contentType);
} catch(Exception e) {
e.printStackTrace();
handler = UnknownContentHandler.INSTANCE;
}
handlers.put(contentType, handler);
}
return handler;
}
/*
* Media types are in the format: type/subtype*(; parameter).
* For looking up the content handler, we should ignore those
* parameters.
*/
private String stripOffParameters(String contentType)
{
if (contentType == null)
return null;
int index = contentType.indexOf(';');
if (index > 0)
return contentType.substring(0, index);
else
return contentType;
}
private static final String contentClassPrefix = "sun.net.www.content";
private static final String contentPathProp = "java.content.handler.pkgs";
/**
* Looks for a content handler in a user-defineable set of places.
* By default it looks in sun.net.www.content, but users can define a
* vertical-bar delimited set of class prefixes to search through in
* addition by defining the java.content.handler.pkgs property.
* The class name must be of the form:
*
* {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 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
* getContentType method.
* 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 http server.
*
* @param is an input stream that supports marks.
* @return a guess at the content type, or 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<