jspwriter.html
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Java 2 Platform EE v1.3: Class JspWriter
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javax.servlet.jsp</FONT>
<BR>
Class JspWriter</H2>
<PRE>
java.lang.Object
|
+--java.io.Writer
|
+--<B>javax.servlet.jsp.JspWriter</B>
</PRE>
<DL>
<DT><B>Direct Known Subclasses:</B> <DD><A HREF="../../../javax/servlet/jsp/tagext/BodyContent.html">BodyContent</A></DD>
</DL>
<HR>
<DL>
<DT>public abstract class <B>JspWriter</B><DT>extends java.io.Writer</DL>
<P>
<p>
The actions and template data in a JSP page is written using the
JspWriter object that is referenced by the implicit variable out which
is initialized automatically using methods in the PageContext object.
<p>
This abstract class emulates some of the functionality found in the
java.io.BufferedWriter and java.io.PrintWriter classes,
however it differs in that it throws java.io.IOException from the print
methods while PrintWriter does not.
<p><B>Buffering</B>
<p>
The initial JspWriter object is associated with the PrintWriter object
of the ServletResponse in a way that depends on whether the page is or
is not buffered. If the page is not buffered, output written to this
JspWriter object will be written through to the PrintWriter directly,
which will be created if necessary by invoking the getWriter() method
on the response object. But if the page is buffered, the PrintWriter
object will not be created until the buffer is flushed and
operations like setContentType() are legal. Since this flexibility
simplifies programming substantially, buffering is the default for JSP
pages.
<p>
Buffering raises the issue of what to do when the buffer is
exceeded. Two approaches can be taken:
<ul>
<li>
Exceeding the buffer is not a fatal error; when the buffer is
exceeded, just flush the output.
<li>
Exceeding the buffer is a fatal error; when the buffer is exceeded,
raise an exception.
</ul>
<p>
Both approaches are valid, and thus both are supported in the JSP
technology. The behavior of a page is controlled by the autoFlush
attribute, which defaults to true. In general, JSP pages that need to
be sure that correct and complete data has been sent to their client
may want to set autoFlush to false, with a typical case being that
where the client is an application itself. On the other hand, JSP
pages that send data that is meaningful even when partially
constructed may want to set autoFlush to true; such as when the
data is sent for immediate display through a browser. Each application
will need to consider their specific needs.
<p>
An alternative considered was to make the buffer size unbounded; but,
this had the disadvantage that runaway computations would consume an
unbounded amount of resources.
<p>
The "out" implicit variable of a JSP implementation class is of this type.
If the page directive selects autoflush="true" then all the I/O operations
on this class shall automatically flush the contents of the buffer if an
overflow condition would result if the current operation were performed
without a flush. If autoflush="false" then all the I/O operations on this
class shall throw an IOException if performing the current operation would
result in a buffer overflow condition.
<P>
<DL>
<DT><B>See Also: </B><DD><CODE>Writer</CODE>,
<CODE>java.io.BufferedWriter</CODE>,
<CODE>PrintWriter</CODE></DL>
<HR>
<P>
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<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>protected boolean</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#autoFlush">autoFlush</A></B></CODE>
<BR>
</TD>
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<CODE>protected int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#bufferSize">bufferSize</A></B></CODE>
<BR>
</TD>
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<CODE>static int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#DEFAULT_BUFFER">DEFAULT_BUFFER</A></B></CODE>
<BR>
constant indicating that the Writer is buffered and is using the implementation default buffer size</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#NO_BUFFER">NO_BUFFER</A></B></CODE>
<BR>
constant indicating that the Writer is not buffering output</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#UNBOUNDED_BUFFER">UNBOUNDED_BUFFER</A></B></CODE>
<BR>
constant indicating that the Writer is buffered and is unbounded; this is used in BodyContent</TD>
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<TD><B>Fields inherited from class java.io.Writer</B></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE>lock</CODE></TD>
</TR>
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<CODE>protected </CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#JspWriter(int, boolean)">JspWriter</A></B>(int bufferSize,
boolean autoFlush)</CODE>
<BR>
protected constructor.</TD>
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<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#clear()">clear</A></B>()</CODE>
<BR>
Clear the contents of the buffer.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#clearBuffer()">clearBuffer</A></B>()</CODE>
<BR>
Clears the current contents of the buffer.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#close()">close</A></B>()</CODE>
<BR>
Close the stream, flushing it first
</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#flush()">flush</A></B>()</CODE>
<BR>
Flush the stream.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#getBufferSize()">getBufferSize</A></B>()</CODE>
<BR>
This method returns the size of the buffer used by the JspWriter.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#getRemaining()">getRemaining</A></B>()</CODE>
<BR>
This method returns the number of unused bytes in the buffer.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> boolean</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#isAutoFlush()">isAutoFlush</A></B>()</CODE>
<BR>
This method indicates whether the JspWriter is autoFlushing.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#newLine()">newLine</A></B>()</CODE>
<BR>
Write a line separator.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#print(boolean)">print</A></B>(boolean b)</CODE>
<BR>
Print a boolean value.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#print(char)">print</A></B>(char c)</CODE>
<BR>
Print a character.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#print(char[])">print</A></B>(char[] s)</CODE>
<BR>
Print an array of characters.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#print(double)">print</A></B>(double d)</CODE>
<BR>
Print a double-precision floating-point number.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>abstract void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/JspWriter.html#print(float)">print</A></B>(float f)</CODE>
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