filesystemregistry.html

j2me 中从本地读取数据JSR075 API 包括 FileConnection 等

					<P></P>
					<DD>
						<DL>
							<DT><B>Parameters:</B><DD><CODE>listener</CODE> - The new FileSystemListener to be 
									registered in order to handle adding/removing file system roots. <DT><B>Returns:</B><DD>boolean 
											indicating if file system listener was successfully added or not <DT><B>Throws:</B>
												<DD>
													<CODE>java.lang.SecurityException</CODE> - if application is not given 
													permission to read files.
													<DD>
														<CODE>java.lang.NullPointerException</CODE> - if listener is <code>null</code>.<DT><B>See 
																Also:</B><DD><A HREF="../../../../javax/microedition/io/file/FileSystemListener.html"><CODE>FileSystemListener</CODE></A>,
																<A HREF="../../../../javax/microedition/io/file/FileConnection.html"><CODE>FileConnection</CODE></A></DD></DL>
					</DD>
			</DL>
			<HR>
			<A NAME="removeFileSystemListener(javax.microedition.io.file.FileSystemListener)"><!-- --></A><H3>
				removeFileSystemListener</H3>
			<PRE>
public static boolean <B>removeFileSystemListener</B>(<A HREF="../../../../javax/microedition/io/file/FileSystemListener.html">FileSystemListener</A>&nbsp;listener)</PRE>
			<DL>
				<DD>
					This method is used to remove a registered FileSystemListener. If file systems 
					are not supported on a device, false is returned from the method.
					<P></P>
					<DD>
						<DL>
							<DT><B>Parameters:</B><DD><CODE>listener</CODE> - The FileSystemListener to be removed. <DT>
										<B>Returns:</B><DD>boolean indicating if file system listener was successfully 
											removed or not <DT><B>Throws:</B>
												<DD>
													<CODE>java.lang.NullPointerException</CODE> - if listener is <code>null</code>.<DT><B>See 
															Also:</B><DD><A HREF="../../../../javax/microedition/io/file/FileSystemListener.html"><CODE>FileSystemListener</CODE></A>,
															<A HREF="../../../../javax/microedition/io/file/FileConnection.html"><CODE>FileConnection</CODE></A></DD></DL>
					</DD>
			</DL>
			<HR>
			<A NAME="listRoots()"><!-- --></A><H3>
				listRoots</H3>
			<PRE>
public static java.util.Enumeration <B>listRoots</B>()</PRE>
			<DL>
				<DD>
					This method returns the currently mounted root file systems on a device as 
					String objects in an Enumeration. If there are no roots available on the 
					device, a zero length Enumeration is returned. If file systems are not 
					supported on a device, a zero length Enumeration is also returned (this check 
					is performed prior to security checks).
					<P>
						The first directory in the file URI is referred to as the <I>root</I>, which 
						corresponds to a logical mount point for a particular storage unit or memory. 
						Root strings are defined by the platform or implementation and can be a string 
						of zero or more characters ("" can be a valid root string on some systems) 
						followed by a trailing "/" to denote that the root is a directory. Each root 
						string is guaranteed to uniquely refer to a root. Root names are device 
						specific and are not required to adhere to any standard. Examples of possible 
						root strings and how to open them include:
						<table border="1">
							<tr>
								<th>
									Possible Root Value</th><th>Opening the Root</th></tr>
							<tr>
								<td>CFCard/</td>
								<td>Connector.open("file:///CFCard/");</td>
							</tr>
							<tr>
								<td>SDCard/</td>
								<td>Connector.open("file:///SDCard/");</td>
							</tr>
							<tr>
								<td>MemoryStick/</td>
								<td>Connector.open("file:///MemoryStick/");</td>
							</tr>
							<tr>
								<td>C:/</td>
								<td>Connector.open("file:///C:/");</td>
							</tr>
							<tr>
								<td>/</td>
								<td>Connector.open("file:////");</td>
							</tr>
						</table>
					<P>
						The following is a sample showing the use of listRoots to retrieve the 
						available size of all roots on a device:
						<pre>   Enumeration rootEnum = FileSystemRegistry.listRoots();
   while (e.hasMoreElements()) {
      String root = (String) e.nextElement();
      FileConnection fc = Connector.open("file:///" + root);
      System.out.println(fc.availableSize());
   } 
 </pre>
					<P></P>
					<DD>
						<DL>
							<DT><B>Returns:</B><DD>an Eumeration of mounted file systems as String objects. <DT><B>Throws:</B>
										<DD>
											<CODE>java.lang.SecurityException</CODE> - if application is not given 
											permission to read files.<DT><B>See Also:</B><DD><A HREF="../../../../javax/microedition/io/file/FileConnection.html"><CODE>FileConnection</CODE></A></DD></DL>
					</DD>
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