fileconnection.html

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

			<PRE>
public java.io.InputStream <B>openInputStream</B>()
                                    throws java.io.IOException</PRE>
			<DL>
				<DD>
					Open and return an input stream for a connection. The connection's target must 
					already exist and be accessible for the input stream to be created.
					<P></P>
					<DD>
						<DL>
							<DT><B>Specified by:</B><DD><CODE>openInputStream</CODE> in interface <CODE>javax.microedition.io.InputConnection</CODE></DD></DL>
						<DD>
							<DL>
								<DT><B>Returns:</B><DD>An open input stream <DT><B>Throws:</B>
											<DD>
												<CODE>java.io.IOException</CODE> - if an I/O error occurs, if the method is 
												invoked on a directory, if the connection's target does not yet exist, or the 
												connection's target is not accessible.
												<DD>
													<CODE><A HREF="../../../../javax/microedition/io/file/IllegalModeException.html">IllegalModeException</A></CODE>
													- if the application does have read access to the connection's target but has 
													opened the connection in <code>Connector.WRITE</code> mode.
													<DD>
														<CODE>java.lang.SecurityException</CODE> - If the application is not granted 
														read access to the connection's target.</DD></DL>
						</DD>
			</DL>
			<HR>
			<A NAME="openDataInputStream()"><!-- --></A><H3>
				openDataInputStream</H3>
			<PRE>
public java.io.DataInputStream <B>openDataInputStream</B>()
                                            throws java.io.IOException</PRE>
			<DL>
				<DD>
					Open and return a data input stream for a connection. The connection's target 
					must already exist and be accessible for the input stream to be created.
					<P></P>
					<DD>
						<DL>
							<DT><B>Specified by:</B><DD><CODE>openDataInputStream</CODE> in interface <CODE>javax.microedition.io.InputConnection</CODE></DD></DL>
						<DD>
							<DL>
								<DT><B>Returns:</B><DD>An open input stream <DT><B>Throws:</B>
											<DD>
												<CODE>java.io.IOException</CODE> - If an I/O error occurs, if the method is 
												invoked on a directory, if the connection's target does not yet exist, or the 
												connection's target is not accessible.
												<DD>
													<CODE><A HREF="../../../../javax/microedition/io/file/IllegalModeException.html">IllegalModeException</A></CODE>
													- if the application does have read access to the connection's target but has 
													opened the connection in <code>Connector.WRITE</code> mode.
													<DD>
														<CODE>java.lang.SecurityException</CODE> - If the application is not granted 
														read access to the connection's target.</DD></DL>
						</DD>
			</DL>
			<HR>
			<A NAME="openOutputStream()"><!-- --></A><H3>
				openOutputStream</H3>
			<PRE>
public java.io.OutputStream <B>openOutputStream</B>()
                                      throws java.io.IOException</PRE>
			<DL>
				<DD>
					Open and return an output stream for a connection. The output stream is 
					positioned at the start of the file. Writing data to the output stream 
					overwrites the contents of the files (i.e. does not insert data). Writing data 
					to output streams beyond the current end of file automatically extends the file 
					size. The connection's target must already exist and be accessible for the 
					output stream to be created. <A HREF="../../../../javax/microedition/io/file/FileConnection.html#openOutputStream(long)">
						<CODE>openOutputStream(long)</CODE></A> should be used to position an 
					output stream to a different position in the file.
					<P>
						Changes made to a file through an output stream may not be immediately made to 
						the actual file residing on the file system because platform and implementation 
						specific use of caching and buffering of the data. Stream contents and file 
						length extensions are not necessarily visible outside of the application 
						immediately unless <code>flush()</code> is called on the stream.&nbsp; The 
						returned output stream is automatically and synchronously flushed when it is 
						closed.
					</P>
					<P></P>
					<DD>
						<DL>
							<DT><B>Specified by:</B><DD><CODE>openOutputStream</CODE> in interface <CODE>javax.microedition.io.OutputConnection</CODE></DD></DL>
						<DD>
							<DL>
								<DT><B>Returns:</B><DD>An open output stream <DT><B>Throws:</B>
											<DD>
												<CODE>java.io.IOException</CODE> - If an I/O error occurs, if the method is 
												invoked on a directory, the file does not yet exist, or the connection's target 
												is not accessible.
												<DD>
													<CODE><A HREF="../../../../javax/microedition/io/file/IllegalModeException.html">IllegalModeException</A></CODE>
													- if the application does have write access to the connection's target but has 
													opened the connection in <code>Connector.READ</code> mode.
													<DD>
														<CODE>java.lang.SecurityException</CODE> - If the application is not granted 
														write access to the connection's target.<DT><B>See Also:</B><DD><A HREF="../../../../javax/microedition/io/file/FileConnection.html#openOutputStream(long)"><CODE>openOutputStream(long)</CODE></A></DD></DL>
						</DD>
			</DL>
			<HR>
			<A NAME="openDataOutputStream()"><!-- --></A><H3>
				openDataOutputStream</H3>
			<PRE>
public java.io.DataOutputStream <B>openDataOutputStream</B>()
                                              throws java.io.IOException</PRE>
			<DL>
				<DD>
					Open and return a data output stream for a connection. The output stream is 
					positioned at the start of the file. Writing data to the output stream 
					overwrites the contents of the files (i.e. does not insert data). Writing data 
					to output streams beyond the current end of file automatically extends the file 
					size. The connection's target must already exist and be accessible for the 
					output stream to be created. <A HREF="../../../../javax/microedition/io/file/FileConnection.html#openOutputStream(long)">
						<CODE>openOutputStream(long)</CODE></A> should be used to position an 
					output stream to a different position in the file.
					<P>
						Changes made to a file through an output stream may not be immediately made to 
						the actual file residing on the file system because platform and implementation 
						specific use of caching and buffering of the data. Stream contents and file 
						length extensions are not necessarily visible outside of the application 
						immediately unless <code>flush()</code> is called on the stream.&nbsp; The 
						returned output stream is automatically and synchronously flushed when it is 
						closed.
					</P>
					<P></P>
					<DD>
						<DL>
							<DT><B>Specified by:</B><DD><CODE>openDataOutputStream</CODE> in interface <CODE>javax.microedition.io.OutputConnection</CODE></DD></DL>
						<DD>
							<DL>
								<DT><B>Returns:</B><DD>An open output stream <DT><B>Throws:</B>
											<DD>
												<CODE>java.io.IOException</CODE> - If an I/O error occurs, if the method is 
												invoked on a directory, the file does not yet exist, or the connection's target 
												is not accessible.
												<DD>
													<CODE><A HREF="../../../../javax/microedition/io/file/IllegalModeException.html">IllegalModeException</A></CODE>
													- if the application does have write access to the connection's target but has 
													opened the connection in <code>Connector.READ</code> mode.
													<DD>
														<CODE>java.lang.SecurityException</CODE> - If the application is not granted 
														write access to the connection's target.<DT><B>See Also:</B><DD><A HREF="../../../../javax/microedition/io/file/FileConnection.html#openOutputStream(long)"><CODE>openOutputStream(long)</CODE></A></DD></DL>
						</DD>
			</DL>
			<HR>
			<A NAME="openOutputStream(long)"><!-- --></A><H3>
				openOutputStream</H3>
			<PRE>
public java.io.OutputStream <B>openOutputStream</B>(long&nbsp;byteOffset)
                                      throws java.io.IOException</PRE>
			<DL>
				<DD>
					This method opens an output stream and positions it at the indicated byte 
					offset in the file. Data written to the returned output stream at that position 
					overwrites any existing data until EOF is reached, and then additional data is 
					appended. The connection's target must already exist and be accessible for the 
					output stream to be created.
					<P>
						Changes made to a file through an output stream may not be immediately made to 
						the actual file residing on the file system because platform and implementation 
						specific use of caching and buffering of the data. Stream contents and file 
						length extensions are not necessarily visible outside of the application 
						immediately unless <code>flush()</code> is called on the stream.&nbsp; The 
						returned output stream is automatically and synchronously flushed when it is 
						closed.
					</P>
					<P></P>
					<DD>
						<DL>
						</DL>
						<DD>
							<DL>
								<DT><B>Parameters:</B><DD><CODE>byteOffset</CODE> - number of bytes to skip over from 
										the beginning of the file when positioning the start of the OutputStream. If 
										the provided offset is larger than or equal to the current file size, the 
										OutputStream is positioned at the current end of the file for appending. <DT><B>Returns:</B><DD>an 
												open OutputStream positioned at the byte offset in the file, or the end of the 
												file if the offset is greater than the size of the file. <DT><B>Throws:</B>
													<DD>
														<CODE>java.io.IOException</CODE> - If an I/O error occurs, if the method is 
														invoked on a directory, the file does not yet exist, or the connection's target 
														is not accessible.
														<DD>
															<CODE><A HREF="../../../../javax/microedition/io/file/IllegalModeException.html">IllegalModeException</A></CODE>
															- if the application does have write access to the connection's target but has 
															opened the connection in <code>Connector.READ</code> mode.
															<DD>
																<CODE>java.lang.SecurityException</CODE> - if the security if the application 
																does not allow write access to the file.
																<DD>
																	<CODE>java.lang.IllegalArgumentException</CODE> - if byteOffset has a negative 
																	value.</DD></DL>
						</DD>
			</DL>
			<HR>
			<A NAME="totalSize()"><!-- --></A><H3>
				totalSize</H3>
			<PRE>
public long <B>totalSize</B>()</PRE>
			<DL>
				<DD>
					Determines the total size of the file system the connection's target resides 
					on.
					<P></P>
					<DD>
						<DL>
						</DL>
						<DD>
							<DL>
								<DT><B>Returns:</B><DD>The total size of the file system in bytes, or -1 if the file 
										system is not accessible. <DT><B>Throws:</B>
											<DD>
												<CODE>java.lang.SecurityException</CODE> - if the security of the application 
												does not have read access to the root volume.
												<DD>
													<CODE><A HREF="../../../../javax/microedition/io/file/IllegalModeException.html">IllegalModeException</A></CODE>
													- if the application does have read access to the connection's target but has 
													opened the connection in <code>Connector.WRITE</code> mode.
													<DD>
														<CODE><A HREF="../../../../javax/microedition/io/file/ConnectionClosedException.html">ConnectionClosedException</A></CODE>
														- if the connection is closed.</DD></DL>
						</DD>
			</DL>
			<HR>
			<A NAME="availableSize()"><!-- --></A><H3>
				availableSize</H3>
			<PRE>
public long <B>availableSize</B>()</PRE>
			<DL>
				<DD>
					Determines the free memory that is available on the file system the file or 
					directory resides on. This may only be an estimate and may vary based on 
					platform-specific file system blocking and metadata information.
					<P></P>
					<DD>
						<DL>
						</DL>
						<DD>
							<DL>
								<DT><B>Returns:</B><DD>The available size in bytes on a file system, or -1 if the file 
										system is not accessible. <DT><B>Throws:</B>