com.dalsemi.shell.server
Class SystemPrintStream

java.lang.Object
  |
  +--java.io.OutputStream
        |
        +--java.io.FilterOutputStream
              |
              +--java.io.PrintStream
                    |
                    +--com.dalsemi.shell.server.SystemPrintStream

public class SystemPrintStream

extends java.io.PrintStream

A basic implementation of a PrintStream for use as System.out and System.err. This class allows its root stream to be set, and overrides all of its parent's (PrintStream) methods. This allows special cases to be handled at the expense of some code space. For instance, a SystemPrintStream can be set to protect itself if an IOException occurs. This is useful, for example, from a telnet session if you run a Java program in the background. The program and the session are both using a socket for output to the user. If the user exits the telnet session, that socket goes away, and the process would receive a SocketException on every write, probably killing the process. If it is set to protect itself, the SystemPrintStream will set its internal root stream to a NullOutputStream when it detects an IOException. Thus, the process can continue to run.

See Also:

SystemInputStream, NullOutputStream, Session

Field Summary

boolean	append If this SystemPrintStream outputs to a file, this variable determines if the output will be appended to the file or if it will over-write the file.
java.lang.String	fileOutName The name of the file this SystemPrintStream is outputting to, or null if this stream is not redirecting to a file.
protected Session	session The user session that owns this SystemPrintStream.
boolean	shieldsUp Allows the SystemPrintStream to protect itself.

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

SystemPrintStream(java.io.OutputStream root)
Creates a new SystemPrintStream with the specified underlying root OutputStream.

SystemPrintStream(java.io.OutputStream out, boolean autoFlush)
Creates a new SystemPrintStream with the specified underlying root OutputStream.

SystemPrintStream(java.io.OutputStream root, java.lang.String fileOutName, boolean append)
Creates a new SystemPrintStream with the specified underlying root OutputStream.

Method Summary

boolean	checkError() Flushes the underlying stream and checks to see if an error (IOException) has occurred while communicating with the underlying root stream.
java.io.OutputStream	getRootOutputStream() Returns the underlying root OutputStream of this stream.
void	print(boolean b) Prints the value of the boolean argument.
void	print(char c) Prints the value of the char argument according to the default encoding scheme.
void	print(char[] s) Prints the char array according to the default encoding scheme.
void	print(double d) Prints the double precision floating point argument by calling the Double.toString(double) method.
void	print(float f) Prints the floating point argument by calling the Float.toString(float) method.
void	print(int i) Prints the int argument by calling the Integer.toString(int) method.
void	print(long l) Prints the long argument by calling the Long.toString(long) method.
void	print(java.lang.Object obj) Prints a String representation of the argument Object by invoking its toString() method, or prints the String "null" if the argument is null.
void	print(java.lang.String s) Prints the String argument to the underlying root stream, or the String "null" if the argument is null.
void	println() Writes the end of line sequence CRLF to the underlying OutputStream.
void	println(boolean x) Prints the value of the boolean argument, followed by the end of line sequence.
void	println(char x) Prints the value of the char argument according to the default encoding scheme, followed by the end of line sequence.
void	println(char[] x) Prints the character array according to the default encoding scheme, followed by the end of line sequence.
void	println(double x) Prints the double precision floating point argument by calling the Double.toString(double) method, followed by the end of line sequence.
void	println(float x) Prints the floating point argument by calling the Float.toString(float) method, followed by the end of line sequence.
void	println(int x) Prints the int argument by calling the Integer.toString(int) method, followed by the end of line sequence.
void	println(long x) Prints the long argument by calling the Long.toString(long) method, followed by the end of line sequence.
void	println(java.lang.Object x) Prints a String representation of the argument Object by invoking its toString() method, or prints the String "null" if the argument is null, followed by the end of line sequence.
void	println(java.lang.String x) Prints the String argument to the underlying root stream, or the String "null" if the argument is null, followed by the end of line sequence.
protected void	setError() Allows another class to signal that an error has occurred.
void	setRootStream(java.io.OutputStream root) Sets the underlying root output stream of this stream.
void	setSession(Session s) Informs this stream of its owning session.
void	write(byte[] buf, int off, int len) Writes a portion of a byte array to the underlying OutputStream.
void	write(int b) Writes the byte to the underlying OutputStream.

Methods inherited from class java.io.PrintStream

close, flush

Methods inherited from class java.io.FilterOutputStream

write

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

session

protected Session session

The user session that owns this SystemPrintStream. This could be a session on the serial port, through a telnet or FTP connection, or through any other user created Session.

fileOutName

public java.lang.String fileOutName

The name of the file this SystemPrintStream is outputting to, or null if this stream is not redirecting to a file.

append

public boolean append

If this SystemPrintStream outputs to a file, this variable determines if the output will be appended to the file or if it will over-write the file.

shieldsUp

public boolean shieldsUp

Allows the SystemPrintStream to protect itself. When a process is run in the background and not redirected to a file, then its OutputStream is in danger of causing problems if the underlying Session is terminated. If the Session ends and the shieldsUp variable is true, this SystemPrintStream's internal root stream must be reassigned to a NullOutputStream.

Constructor Detail

SystemPrintStream

public SystemPrintStream(java.io.OutputStream root)

Creates a new SystemPrintStream with the specified underlying root OutputStream.

Parameters:

root - the internal root OutputStream for this SystemPrintStream

SystemPrintStream

public SystemPrintStream(java.io.OutputStream out,
                         boolean autoFlush)

Creates a new SystemPrintStream with the specified underlying root OutputStream.

Parameters:

root - the internal root OutputStream for this SystemPrintStream

autoFlush - set to true if the SystemPrintStream should flush the internal root stream on every write call

SystemPrintStream

public SystemPrintStream(java.io.OutputStream root,
                         java.lang.String fileOutName,
                         boolean append)

Creates a new SystemPrintStream with the specified underlying root OutputStream. In this case, the underlying root stream should be for a file.

Parameters:

root - the internal root OutputStream for this SystemPrintStream

fileOutName - name of the file this SystemPrintStream is directing its output towards

append - true if this SystemPrintStream should append to the file, false if it should over-write the file

Method Detail

setRootStream

public void setRootStream(java.io.OutputStream root)

Sets the underlying root output stream of this stream.

Parameters:

root - the new underlying stream to use

See Also:

getRootOutputStream()

getRootOutputStream

public java.io.OutputStream getRootOutputStream()

Returns the underlying root OutputStream of this stream.

Returns:

the underlying root stream

See Also:

setRootStream(java.io.OutputStream)

setSession

public void setSession(Session s)

Informs this stream of its owning session. This allows this stream to call into the session when needed.

Parameters:

session - the owning session

checkError

public boolean checkError()

Flushes the underlying stream and checks to see if an error (IOException) has occurred while communicating with the underlying root stream. The error state is not cleared: if an error has occurred, all successive calls to checkError() return true.

Returns:

true if an IOException has occurred

Overrides:

checkError in class java.io.PrintStream

setError

protected void setError()

Allows another class to signal that an error has occurred.

Overrides:

setError in class java.io.PrintStream

write

public void write(int b)

Writes the byte to the underlying OutputStream.

Parameters:

b - value to be written

Overrides:

write in class java.io.PrintStream

write

public void write(byte[] buf,
                  int off,
                  int len)

Writes a portion of a byte array to the underlying OutputStream.

Parameters:

buf - a byte array

off - offset in the byte array to begin writing bytes from

len - number of bytes to write

Overrides:

write in class java.io.PrintStream

print

public void print(boolean b)

Prints the value of the boolean argument. If the argument is true, the String "true" is printed. If the argument is false, the String "false" is printed.

Parameters:

b - the boolean value to print

Overrides:

print in class java.io.PrintStream

See Also:

println(boolean)

print

public void print(char c)

Prints the value of the char argument according to the default encoding scheme.

Parameters:

c - the char to be printed

Overrides:

print in class java.io.PrintStream

See Also:

println(char)

print

public void print(int i)

Prints the int argument by calling the Integer.toString(int) method.

Parameters:

i - the int to be printed

Overrides:

print in class java.io.PrintStream

See Also:

println(int)

print

public void print(long l)

Prints the long argument by calling the Long.toString(long) method.

Parameters:

l - the long to be printed

Overrides:

print in class java.io.PrintStream

See Also:

println(long)

print

public void print(float f)

Prints the floating point argument by calling the Float.toString(float) method.

Parameters:

f - the float to be printed

Overrides:

print in class java.io.PrintStream

See Also:

println(float)

print

public void print(double d)

Prints the double precision floating point argument by calling the Double.toString(double) method.

Parameters:

d - the double to be printed

Overrides:

print in class java.io.PrintStream

See Also:

println(double)

print

public void print(char[] s)

Prints the char array according to the default encoding scheme.

Parameters:

s - the char array to be printed

Overrides:

print in class java.io.PrintStream

See Also:

println(char[])

print

public void print(java.lang.String s)

Prints the String argument to the underlying root stream, or the String "null" if the argument is null.

Parameters:

s - the String to print

Overrides:

print in class java.io.PrintStream

See Also:

println(java.lang.String)

print

public void print(java.lang.Object obj)

Prints a String representation of the argument Object by invoking its toString() method, or prints the String "null" if the argument is null.

Parameters:

obj - the Object to print

Overrides:

print in class java.io.PrintStream

See Also:

println(java.lang.Object)

println

public void println()

Writes the end of line sequence CRLF to the underlying OutputStream.

Overrides:

println in class java.io.PrintStream

println

public void println(boolean x)

Prints the value of the boolean argument, followed by the end of line sequence. If the argument is true, the String "true" is printed. If the argument is false, the String "false" is printed.

Parameters:

x - the boolean value to print

Overrides:

println in class java.io.PrintStream

See Also:

print(boolean)

println

public void println(char x)

Prints the value of the char argument according to the default encoding scheme, followed by the end of line sequence.

Parameters:

x - the char to be printed

Overrides:

println in class java.io.PrintStream

See Also:

print(char)

println

public void println(int x)

Prints the int argument by calling the Integer.toString(int) method, followed by the end of line sequence.

Parameters:

x - the int to be printed

Overrides:

println in class java.io.PrintStream

See Also:

print(int)

println

public void println(long x)

Prints the long argument by calling the Long.toString(long) method, followed by the end of line sequence.

Parameters:

x - the long to be printed

Overrides:

println in class java.io.PrintStream

See Also:

print(long)

println

public void println(float x)

Prints the floating point argument by calling the Float.toString(float) method, followed by the end of line sequence.

Parameters:

x - the float to be printed

Overrides:

println in class java.io.PrintStream

See Also:

print(float)

println

public void println(double x)

Prints the double precision floating point argument by calling the Double.toString(double) method, followed by the end of line sequence.

Parameters:

x - the double to be printed

Overrides:

println in class java.io.PrintStream

See Also:

print(double)

println

public void println(char[] x)

Prints the character array according to the default encoding scheme, followed by the end of line sequence.

Parameters:

x - the char array to be printed

Overrides:

println in class java.io.PrintStream

See Also:

print(char[])

println

public void println(java.lang.String x)

Prints the String argument to the underlying root stream, or the String "null" if the argument is null, followed by the end of line sequence.

Parameters:

x - the String to print

Overrides:

println in class java.io.PrintStream

See Also:

print(java.lang.String)

println

public void println(java.lang.Object x)

Prints a String representation of the argument Object by invoking its toString() method, or prints the String "null" if the argument is null, followed by the end of line sequence.

Parameters:

x - the Object to print

Overrides:

println in class java.io.PrintStream

See Also:

print(java.lang.Object)