Ja-Jakarta
Translation

javax.servlet.jsp
クラス JspWriter

java.lang.Object
  上位を拡張 java.io.Writer
      上位を拡張 javax.servlet.jsp.JspWriter
すべての実装されたインタフェース:
java.io.Closeable, java.io.Flushable, java.lang.Appendable
直系の既知のサブクラス:
BodyContent

public abstract class JspWriter
extends java.io.Writer

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.

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.

Buffering

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.

Buffering raises the issue of what to do when the buffer is exceeded. Two approaches can be taken:

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.

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.

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.

関連項目:
Writer, BufferedWriter, PrintWriter

フィールドの概要
protected  boolean autoFlush
          Whether the JspWriter is autoflushing.
protected  int bufferSize
          The size of the buffer used by the JspWriter.
static int DEFAULT_BUFFER
          Constant indicating that the Writer is buffered and is using the implementation default buffer size.
static int NO_BUFFER
          Constant indicating that the Writer is not buffering output.
static int UNBOUNDED_BUFFER
          Constant indicating that the Writer is buffered and is unbounded; this is used in BodyContent.
 
クラス java.io.Writer から継承されたフィールド
lock
 
コンストラクタの概要
protected JspWriter(int bufferSize, boolean autoFlush)
          Protected constructor.
 
メソッドの概要
abstract  void clear()
          Clear the contents of the buffer.
abstract  void clearBuffer()
          Clears the current contents of the buffer.
abstract  void close()
          Close the stream, flushing it first.
abstract  void flush()
          Flush the stream.
 int getBufferSize()
          This method returns the size of the buffer used by the JspWriter.
abstract  int getRemaining()
          This method returns the number of unused bytes in the buffer.
 boolean isAutoFlush()
          This method indicates whether the JspWriter is autoFlushing.
abstract  void newLine()
          Write a line separator.
abstract  void print(boolean b)
          Print a boolean value.
abstract  void print(char c)
          Print a character.
abstract  void print(char[] s)
          Print an array of characters.
abstract  void print(double d)
          Print a double-precision floating-point number.
abstract  void print(float f)
          Print a floating-point number.
abstract  void print(int i)
          Print an integer.
abstract  void print(long l)
          Print a long integer.
abstract  void print(java.lang.Object obj)
          Print an object.
abstract  void print(java.lang.String s)
          Print a string.
abstract  void println()
          Terminate the current line by writing the line separator string.
abstract  void println(boolean x)
          Print a boolean value and then terminate the line.
abstract  void println(char x)
          Print a character and then terminate the line.
abstract  void println(char[] x)
          Print an array of characters and then terminate the line.
abstract  void println(double x)
          Print a double-precision floating-point number and then terminate the line.
abstract  void println(float x)
          Print a floating-point number and then terminate the line.
abstract  void println(int x)
          Print an integer and then terminate the line.
abstract  void println(long x)
          Print a long integer and then terminate the line.
abstract  void println(java.lang.Object x)
          Print an Object and then terminate the line.
abstract  void println(java.lang.String x)
          Print a String and then terminate the line.
 
クラス java.io.Writer から継承されたメソッド
append, append, append, write, write, write, write, write
 
クラス java.lang.Object から継承されたメソッド
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

フィールドの詳細

NO_BUFFER

public static final int NO_BUFFER
Constant indicating that the Writer is not buffering output.

関連項目:
定数フィールド値

DEFAULT_BUFFER

public static final int DEFAULT_BUFFER
Constant indicating that the Writer is buffered and is using the implementation default buffer size.

関連項目:
定数フィールド値

UNBOUNDED_BUFFER

public static final int UNBOUNDED_BUFFER
Constant indicating that the Writer is buffered and is unbounded; this is used in BodyContent.

関連項目:
定数フィールド値

bufferSize

protected int bufferSize
The size of the buffer used by the JspWriter.


autoFlush

protected boolean autoFlush
Whether the JspWriter is autoflushing.

コンストラクタの詳細

JspWriter

protected JspWriter(int bufferSize,
                    boolean autoFlush)
Protected constructor.

パラメータ:
bufferSize - the size of the buffer to be used by the JspWriter
autoFlush - whether the JspWriter should be autoflushing
メソッドの詳細

newLine

public abstract void newLine()
                      throws java.io.IOException
Write a line separator. The line separator string is defined by the system property line.separator, and is not necessarily a single newline ('\n') character.

例外:
java.io.IOException - If an I/O error occurs

print

public abstract void print(boolean b)
                    throws java.io.IOException
Print a boolean value. The string produced by String.valueOf(boolean) is written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
b - The boolean to be printed
例外:
java.io.IOException - If an error occured while writing

print

public abstract void print(char c)
                    throws java.io.IOException
Print a character. The character is written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
c - The char to be printed
例外:
java.io.IOException - If an error occured while writing

print

public abstract void print(int i)
                    throws java.io.IOException
Print an integer. The string produced by String.valueOf(int) is written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
i - The int to be printed
例外:
java.io.IOException - If an error occured while writing
関連項目:
Integer.toString(int)

print

public abstract void print(long l)
                    throws java.io.IOException
Print a long integer. The string produced by String.valueOf(long) is written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
l - The long to be printed
例外:
java.io.IOException - If an error occured while writing
関連項目:
Long.toString(long)

print

public abstract void print(float f)
                    throws java.io.IOException
Print a floating-point number. The string produced by String.valueOf(float) is written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
f - The float to be printed
例外:
java.io.IOException - If an error occured while writing
関連項目:
Float.toString(float)

print

public abstract void print(double d)
                    throws java.io.IOException
Print a double-precision floating-point number. The string produced by String.valueOf(double) is written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
d - The double to be printed
例外:
java.io.IOException - If an error occured while writing
関連項目:
Double.toString(double)

print

public abstract void print(char[] s)
                    throws java.io.IOException
Print an array of characters. The characters are written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
s - The array of chars to be printed
例外:
java.lang.NullPointerException - If s is null
java.io.IOException - If an error occured while writing

print

public abstract void print(java.lang.String s)
                    throws java.io.IOException
Print a string. If the argument is null then the string "null" is printed. Otherwise, the string's characters are written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
s - The String to be printed
例外:
java.io.IOException - If an error occured while writing

print

public abstract void print(java.lang.Object obj)
                    throws java.io.IOException
Print an object. The string produced by the String.valueOf(Object) method is written to the JspWriter's buffer or, if no buffer is used, directly to the underlying writer.

パラメータ:
obj - The Object to be printed
例外:
java.io.IOException - If an error occured while writing
関連項目:
Object.toString()

println

public abstract void println()
                      throws java.io.IOException
Terminate the current line by writing the line separator string. The line separator string is defined by the system property line.separator, and is not necessarily a single newline character ('\n').

例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(boolean x)
                      throws java.io.IOException
Print a boolean value and then terminate the line. This method behaves as though it invokes print(boolean) and then println().

パラメータ:
x - the boolean to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(char x)
                      throws java.io.IOException
Print a character and then terminate the line. This method behaves as though it invokes print(char) and then println().

パラメータ:
x - the char to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(int x)
                      throws java.io.IOException
Print an integer and then terminate the line. This method behaves as though it invokes print(int) and then println().

パラメータ:
x - the int to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(long x)
                      throws java.io.IOException
Print a long integer and then terminate the line. This method behaves as though it invokes print(long) and then println().

パラメータ:
x - the long to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(float x)
                      throws java.io.IOException
Print a floating-point number and then terminate the line. This method behaves as though it invokes print(float) and then println().

パラメータ:
x - the float to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(double x)
                      throws java.io.IOException
Print a double-precision floating-point number and then terminate the line. This method behaves as though it invokes print(double) and then println().

パラメータ:
x - the double to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(char[] x)
                      throws java.io.IOException
Print an array of characters and then terminate the line. This method behaves as though it invokes print(char[]) and then println().

パラメータ:
x - the char[] to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(java.lang.String x)
                      throws java.io.IOException
Print a String and then terminate the line. This method behaves as though it invokes print(String) and then println().

パラメータ:
x - the String to write
例外:
java.io.IOException - If an error occured while writing

println

public abstract void println(java.lang.Object x)
                      throws java.io.IOException
Print an Object and then terminate the line. This method behaves as though it invokes print(Object) and then println().

パラメータ:
x - the Object to write
例外:
java.io.IOException - If an error occured while writing

clear

public abstract void clear()
                    throws java.io.IOException
Clear the contents of the buffer. If the buffer has been already been flushed then the clear operation shall throw an IOException to signal the fact that some data has already been irrevocably written to the client response stream.

例外:
java.io.IOException - If an I/O error occurs

clearBuffer

public abstract void clearBuffer()
                          throws java.io.IOException
Clears the current contents of the buffer. Unlike clear(), this method will not throw an IOException if the buffer has already been flushed. It merely clears the current content of the buffer and returns.

例外:
java.io.IOException - If an I/O error occurs

flush

public abstract void flush()
                    throws java.io.IOException
Flush the stream. If the stream has saved any characters from the various write() methods in a buffer, write them immediately to their intended destination. Then, if that destination is another character or byte stream, flush it. Thus one flush() invocation will flush all the buffers in a chain of Writers and OutputStreams.

The method may be invoked indirectly if the buffer size is exceeded.

Once a stream has been closed, further write() or flush() invocations will cause an IOException to be thrown.

定義:
インタフェース java.io.Flushable 内の flush
定義:
クラス java.io.Writer 内の flush
例外:
java.io.IOException - If an I/O error occurs

close

public abstract void close()
                    throws java.io.IOException
Close the stream, flushing it first.

This method needs not be invoked explicitly for the initial JspWriter as the code generated by the JSP container will automatically include a call to close().

Closing a previously-closed stream, unlike flush(), has no effect.

定義:
インタフェース java.io.Closeable 内の close
定義:
クラス java.io.Writer 内の close
例外:
java.io.IOException - If an I/O error occurs

getBufferSize

public int getBufferSize()
This method returns the size of the buffer used by the JspWriter.

戻り値:
the size of the buffer in bytes, or 0 is unbuffered.

getRemaining

public abstract int getRemaining()
This method returns the number of unused bytes in the buffer.

戻り値:
the number of bytes unused in the buffer

isAutoFlush

public boolean isAutoFlush()
This method indicates whether the JspWriter is autoFlushing.

戻り値:
if this JspWriter is auto flushing or throwing IOExceptions on buffer overflow conditions

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