FileDocCategorySizeDatePackage
URLConnection.javaAPI DocExample47799Sat Sep 09 21:21:12 BST 2000java.net

URLConnection

public abstract class URLConnection extends Object
The abstract class 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.
---------------------------->
time
  1. The connection object is created by invoking the openConnection method on a URL.
  2. The setup parameters and general request properties are manipulated.
  3. The actual connection to the remote object is made, using the connect method.
  4. The remote object becomes available. The header fields and the contents of the remote object can be accessed.

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. Default values for general request properties can be set using the setDefaultRequestProperty method.

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 getObject, 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:

http://www.w3.org/hypertext/WWW/Protocols/HTTP1.0/draft-ietf-http-spec.html
Note about 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 JDK Compatibility page.
author
James Gosling
version
1.54, 10/02/98
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#setDefaultRequestProperty(java.lang.String, java.lang.String)
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

Fields Summary
protected URL
url
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.

protected boolean
doInput
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.

protected boolean
doOutput
This variable is set by the setDoOutput method. Its value is returned by the getDoInput 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.

private static boolean
defaultAllowUserInteraction
protected boolean
allowUserInteraction
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.

private static boolean
defaultUseCaches
protected boolean
useCaches
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.

protected long
ifModifiedSince
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 seconds 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.

protected boolean
connected
If false, this connection object has not created a communications link to the specified URL. If true, the communications link has been established.
private static FileNameMap
fileNameMap
static ContentHandlerFactory
factory
The ContentHandler factory.
private static Hashtable
handlers
private static final ContentHandler
UnknownContentHandlerP
private static final String
contentClassPrefix
private static final String
contentPathProp
Constructors Summary
protected URLConnection(URL url)
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.

	this.url = url;
    
Methods Summary
private static booleancheckfpx(java.io.InputStream is)
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.

        /* 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 skipped = 0;
	while (skipped != toSkip) {
	    skipped += is.skip(toSkip - skipped);
	}
	long posn = skipped;
	int byteOrder = is.read();
	is.read();
	posn+=2;
	int uSectorShift;
	if(byteOrder == 0xFE) {
	    uSectorShift = is.read();
	    uSectorShift += is.read() << 8;
	}
	else {
	    uSectorShift = is.read() << 8;
	    uSectorShift += is.read();
	}
	posn += 2;
	toSkip = (long)0x30 - posn;
	skipped = 0;
	while (skipped != toSkip) {
	    skipped += is.skip(toSkip - skipped);
	}
	posn += skipped;
	int sectDirStart;
	if(byteOrder == 0xFE) {
	    sectDirStart = is.read();
	    sectDirStart += is.read()<<8;
	    sectDirStart += is.read()<<16;
	    sectDirStart += is.read()<<24;
	}
	else {
	    sectDirStart = is.read()<<24;
	    sectDirStart += is.read()<<16;
	    sectDirStart += is.read()<<8;
	    sectDirStart += is.read();
	}
	posn += 4;
	is.reset(); // Reset back to the beginning

	toSkip = (long)0x200 + 
		(long)((int)1<<uSectorShift)*sectDirStart + (long)0x50;

	// How far can we skip? Is there any performance problem here?
	// This skip can be fairly long, at least 0x4c650 in at least
	// one case. Have to assume that the skip will fit in an int.
	is.mark((int)toSkip+0x30); // Leave room to read whole root dir
	skipped = 0;
	while (skipped != toSkip) {
	    skipped += is.skip(toSkip - skipped);
	}
	/* should be at beginning of ClassID, which is as follows
	 * (in Intel byte order):
	 *    00 67 61 56 54 C1 CE 11 85 53 00 AA 00 A1 F9 5B
	 *
	 * This is stored from Windows as long,short,short,char[8]
	 * so for byte order changes, the order only changes for 
	 * the first 8 bytes in the ClassID.
	 *
	 * Test against this, ignoring second byte (Intel) since 
	 * this could change depending on part of Fpx file we have.
	 */
	int c[] = new int[16];

	for (int i=0; i<16; i++) c[i] = is.read();
	// intel byte order
	if (byteOrder == 0xFE && 
	    c[0] == 0x00 && c[2] == 0x61 && c[3] == 0x56 &&
	    c[4] == 0x54 && c[5] == 0xC1 && c[6] == 0xCE &&
	    c[7] == 0x11 && c[8] == 0x85 && c[9] == 0x53 &&
	    c[10]== 0x00 && c[11]== 0xAA && c[12]== 0x00 &&
	    c[13]== 0xA1 && c[14]== 0xF9 && c[15]== 0x5B) {
	    is.reset();
	    return true;
	}
	// non-intel byte order
	else if (c[3] == 0x00 && c[1] == 0x61 && c[0] == 0x56 &&
	    c[5] == 0x54 && c[4] == 0xC1 && c[7] == 0xCE &&
	    c[6] == 0x11 && c[8] == 0x85 && c[9] == 0x53 &&
	    c[10]== 0x00 && c[11]== 0xAA && c[12]== 0x00 &&
	    c[13]== 0xA1 && c[14]== 0xF9 && c[15]== 0x5B) {
	    is.reset();
	    return true;
	}
    is.reset();
    return false;
    
public abstract voidconnect()
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.

exception
IOException if an I/O error occurs while opening the connection.
see
java.net.URLConnection#connected

public booleangetAllowUserInteraction()
Returns the value of the allowUserInteraction field for this object.

return
the value of the allowUserInteraction field for this object.
see
java.net.URLConnection#allowUserInteraction

	return allowUserInteraction;
    
public java.lang.ObjectgetContent()
Retrieves the contents of this URL connection.

This method first determines the content type of the object by calling the 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:

  1. If the application has set up a content handler factory instance using 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.
  2. If no content handler factory has yet been set up, or if the factory's createContentHandler method returns null, then the application loads the class named:
    sun.net.www.content.<contentType>
    
    where <contentType> is formed by taking the content-type string, replacing all slash characters with a 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.

return
the object fetched. The instanceOf operation 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)

        // 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);
    
public java.lang.StringgetContentEncoding()
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)

	return getHeaderField("content-encoding");
    
synchronized java.net.ContentHandlergetContentHandler()
Gets the Content Handler appropriate for this connection.

param
connection the connection to use.


                       
      
     
    
	String contentType = getContentType();
	ContentHandler handler = null;
	if (contentType == null)
	    throw new UnknownServiceException("no content-type");
	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 = UnknownContentHandlerP;
	    }
	    handlers.put(contentType, handler);
	}
	return handler;
    
private java.lang.StringgetContentHandlerPkgPrefixes()
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.

	String packagePrefixList = (String) AccessController.doPrivileged(
            new sun.security.action.GetPropertyAction(contentPathProp, ""));

	if (packagePrefixList != "") {
	    packagePrefixList += "|";
	}
	
	return packagePrefixList + contentClassPrefix;
    
public intgetContentLength()
Returns the value of the content-length header field.

return
the content length of the resource that this connection's URL references, or -1 if the content length is not known.

	return getHeaderFieldInt("content-length", -1);
    
public java.lang.StringgetContentType()
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)

	return getHeaderField("content-type");
    
public longgetDate()
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 seconds since January 1, 1970 GMT.
see
java.net.URLConnection#getHeaderField(java.lang.String)

	return getHeaderFieldDate("date", 0);
    
public static booleangetDefaultAllowUserInteraction()
Returns the default value of the 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 allowUserInteraction field.
see
java.net.URLConnection#allowUserInteraction

	return defaultAllowUserInteraction;
    
public static java.lang.StringgetDefaultRequestProperty(java.lang.String key)
Returns the value of the default request property. Default request properties are set for every connection.

return
the value of the default request property for the specified key.
see
java.net.URLConnection#setDefaultRequestProperty(java.lang.String, java.lang.String)

	return null;
    
public booleangetDefaultUseCaches()
Returns the default value of a URLConnection's 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 URLConnection's useCaches flag.
see
java.net.URLConnection#useCaches

	return defaultUseCaches;
    
public booleangetDoInput()
Returns the value of this URLConnection's doInput flag.

return
the value of this URLConnection's doInput flag.
see
java.net.URLConnection#doInput

	return doInput;
    
public booleangetDoOutput()
Returns the value of this URLConnection's doOutput flag.

return
the value of this URLConnection's doOutput flag.
see
java.net.URLConnection#doOutput

	return doOutput;
    
public longgetExpiration()
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 seconds since January 1, 1970 GMT.
see
java.net.URLConnection#getHeaderField(java.lang.String)

	return getHeaderFieldDate("expires", 0);
    
public static java.net.FileNameMapgetFileNameMap()
Returns the FileNameMap.

returns
the FileNameMap
since
JDK1.2


                 
        
	return new FileNameMap() {
            public String getContentTypeFor(String fileName) {
                return fileNameMap.getContentTypeFor(fileName);
            }
        };
    
public java.lang.StringgetHeaderField(java.lang.String name)
Returns the name of the specified header field.

param
name the name of a header field.
return
the value of the named header field, or null if there is no such field in the header.

	return null;
    
public java.lang.StringgetHeaderField(int n)
Returns the value for the nth header field. It returns null if there are fewer than n fields.

This method can be used in conjunction with the getHeaderFieldKey method to iterate through all the headers in the message.

param
n an index.
return
the value of the nth header field.
see
java.net.URLConnection#getHeaderFieldKey(int)

	return null;
    
public longgetHeaderFieldDate(java.lang.String name, long Default)
Returns the value of the named field parsed as date. The result is the number of seconds since January 1, 1970 GMT represented by the named field.

This form of 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.

	try {
	    return Date.parse(getHeaderField(name));
	} catch(Throwable t) {}
	return Default;
    
public intgetHeaderFieldInt(java.lang.String name, int Default)
Returns the value of the named field parsed as a number.

This form of 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 an integer. The Default value is returned if the field is missing or malformed.

	try {
	    return Integer.parseInt(getHeaderField(name));
	} catch(Throwable t) {}
	return Default;
    
public java.lang.StringgetHeaderFieldKey(int n)
Returns the key for the nth header field.

param
n an index.
return
the key for the nth header field, or null if there are fewer than n fields.

	return null;
    
public longgetIfModifiedSince()
Returns the value of this object's ifModifiedSince field.

return
the value of this object's ifModifiedSince field.
see
java.net.URLConnection#ifModifiedSince

	return ifModifiedSince;
    
public java.io.InputStreamgetInputStream()
Returns an input stream that reads from this open connection.

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.

	throw new UnknownServiceException("protocol doesn't support input");
    
public longgetLastModified()
Returns the value of the last-modified header field. The result is the number of seconds 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)

	return getHeaderFieldDate("last-modified", 0);
    
public java.io.OutputStreamgetOutputStream()
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.

	throw new UnknownServiceException("protocol doesn't support output");
    
public java.security.PermissiongetPermission()
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.

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.

	return new java.security.AllPermission();
    
public java.lang.StringgetRequestProperty(java.lang.String key)
Returns the value of the named general request property for this connection.

return
the value of the named general request property for this connection.

	if (connected)
	    throw new IllegalAccessError("Already connected");
	return null;
    
public java.net.URLgetURL()
Returns the value of this URLConnection's URL field.

return
the value of this URLConnection's URL field.
see
java.net.URLConnection#url

	return url;
    
public booleangetUseCaches()
Returns the value of this URLConnection's useCaches field.

return
the value of this URLConnection's useCaches field.
see
java.net.URLConnection#useCaches

	return useCaches;
    
protected static java.lang.StringguessContentTypeFromName(java.lang.String fname)
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()

	String contentType = null;
	if (fileNameMap != null) {
	    contentType = fileNameMap.getContentTypeFor(fname);
	}

	return contentType;
    
public static java.lang.StringguessContentTypeFromStream(java.io.InputStream is)
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.

Ideally, this routine would not be needed. But many 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()

	is.mark(10);
	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();
	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 == '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 == 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 == '<")
	    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 (c1 == 0xFF && c2 == 0xD8 && c3 == 0xFF && c4 == 0xE0)
	    return "image/jpeg";
	if (c1 == 0xFF && c2 == 0xD8 && c3 == 0xFF && c4 == 0xEE)
	    return "image/jpg";

	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";  
	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";
	}
	return null;
    
private java.net.ContentHandlerlookupContentHandlerClassFor(java.lang.String contentType)
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


                                                                      
       
	    
	     System.err.println("Content type: " + contentType);
	String contentHandlerClassName = typeToPackageName(contentType);
	     System.err.println("contentHandlerClassName: " + contentHandlerClassName);

	String contentHandlerPkgPrefixes =getContentHandlerPkgPrefixes();
	     System.err.println("contentHandlerPkgPrefixes: " + contentHandlerPkgPrefixes);

	StringTokenizer packagePrefixIter =
	    new StringTokenizer(contentHandlerPkgPrefixes, "|");
	
	while (packagePrefixIter.hasMoreTokens()) {
	    String packagePrefix = packagePrefixIter.nextToken().trim();
	     System.err.println("packagePrefix: " + packagePrefix);

	    try {
		String name = packagePrefix + "." + contentHandlerClassName;
	     System.err.println("name: " + name);
		ContentHandler handler =
		    (ContentHandler) Class.forName(name).newInstance();
		return handler;
	  } catch(Exception e) {
	     System.err.println(e);
	    }
	}
	
	return UnknownContentHandlerP;
    
public voidsetAllowUserInteraction(boolean allowuserinteraction)
Set the value of the allowUserInteraction field of this URLConnection.

param
allowuserinteraction the new value.
see
java.net.URLConnection#allowUserInteraction

	if (connected)
	    throw new IllegalAccessError("Already connected");
	allowUserInteraction = allowuserinteraction;
    
public static synchronized voidsetContentHandlerFactory(java.net.ContentHandlerFactory fac)
Sets the ContentHandlerFactory of an application. It can be called at most once by an application.

The 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 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

	if (factory != null) {
	    throw new Error("factory already defined");
	}
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	    security.checkSetFactory();
	}
	factory = fac;
    
public static voidsetDefaultAllowUserInteraction(boolean defaultallowuserinteraction)
Sets the default value of the allowUserInteraction field for all future URLConnection objects to the specified value.

param
defaultallowuserinteraction the new value.
see
java.net.URLConnection#allowUserInteraction

	defaultAllowUserInteraction = defaultallowuserinteraction;
    
public static voidsetDefaultRequestProperty(java.lang.String key, java.lang.String value)
Sets the default value of a general request property. When a URLConnection 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.

    
public voidsetDefaultUseCaches(boolean defaultusecaches)
Sets the default value of the useCaches field to the specified value.

param
defaultusecaches the new value.
see
java.net.URLConnection#useCaches

	defaultUseCaches = defaultusecaches;
    
public voidsetDoInput(boolean doinput)
Sets the value of the doInput field for this 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 unless DoOutput is explicitly set to true, in which case DoInput defaults to false.

param
value the new value.
see
java.net.URLConnection#doInput

	if (connected)
	    throw new IllegalAccessError("Already connected");
	doInput = doinput;
    
public voidsetDoOutput(boolean dooutput)
Sets the value of the doOutput field for this 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
value the new value.
see
java.net.URLConnection#doOutput

	if (connected)
	    throw new IllegalAccessError("Already connected");
	doOutput = dooutput;
    
public static voidsetFileNameMap(java.net.FileNameMap map)
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
since
JDK1.2

	SecurityManager sm = System.getSecurityManager();
	if (sm != null) sm.checkSetFactory();
	fileNameMap = map;
    
public voidsetIfModifiedSince(long ifmodifiedsince)
Sets the value of the ifModifiedSince field of this URLConnection to the specified value.

param
value the new value.
see
java.net.URLConnection#ifModifiedSince

	if (connected)
	    throw new IllegalAccessError("Already connected");
	ifModifiedSince = ifmodifiedsince;
    
public voidsetRequestProperty(java.lang.String key, java.lang.String value)
Sets the general request property.

param
key the keyword by which the request is known (e.g., "accept").
param
value the value associated with it.

	if (connected)
	    throw new IllegalAccessError("Already connected");
    
public voidsetUseCaches(boolean usecaches)
Sets the value of the useCaches field of this 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.

see
java.net.URLConnection#useCaches

	if (connected)
	    throw new IllegalAccessError("Already connected");
	useCaches = usecaches;
    
public java.lang.StringtoString()
Returns a String representation of this URL connection.

return
a string representation of this URLConnection.

	return this.getClass().getName() + ":" + url;
    
private java.lang.StringtypeToPackageName(java.lang.String contentType)
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"

	// 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);