java.io
Class InputStreamReader

java.lang.Object
  java.io.Reader
      java.io.InputStreamReader

All Implemented Interfaces:

Closeable, Readable

Direct Known Subclasses:

FileReader

public class InputStreamReader
extends Reader

InputStreamReader is class for turning a byte Stream into a character Stream. Data read from the source input stream is converted into characters by either a default or provided character converter. By default, the encoding is assumed to ISO8859_1. The InputStreamReader contains a buffer of bytes read from the source input stream and converts these into characters as needed. The buffer size is 8K.

See Also:

OutputStreamWriter

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

InputStreamReader(InputStream in)
Constructs a new InputStreamReader on the InputStream in.

InputStreamReader(InputStream in, Charset charset)
Constructs a new InputStreamReader on the InputStream in.

InputStreamReader(InputStream in, CharsetDecoder decoder)
Constructs a new InputStreamReader on the InputStream in.

InputStreamReader(InputStream in, String enc)
Constructs a new InputStreamReader on the InputStream in.

Method Summary

void	close() Close this InputStreamReader.
String	getEncoding() Answer the String which identifies the encoding used to convert bytes to characters.
int	read() Reads a single character from this InputStreamReader and returns the result as an int.
int	read(char[] buf, int offset, int length) Reads at most count characters from this Reader and stores them at offset in the character array buf.
boolean	ready() Answers a boolean indicating whether or not this InputStreamReader is ready to be read without blocking.

Methods inherited from class java.io.Reader

mark, markSupported, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

InputStreamReader

public InputStreamReader(InputStream in)

Constructs a new InputStreamReader on the InputStream in. Now character reading can be filtered through this InputStreamReader. This constructor uses the Charset.defaultCharset().

Parameters:

in - the InputStream to convert to characters.

InputStreamReader

public InputStreamReader(InputStream in,
                         String enc)
                  throws UnsupportedEncodingException

Constructs a new InputStreamReader on the InputStream in. Now character reading can be filtered through this InputStreamReader. This constructor takes a String parameter enc which is the name of an encoding. If the encoding cannot be found, an UnsupportedEncodingException error is thrown.

Parameters:

in - the InputStream to convert to characters.

enc - a String describing the character converter to use.

Throws:

UnsupportedEncodingException - if the encoding cannot be found.

InputStreamReader

public InputStreamReader(InputStream in,
                         Charset charset)

Constructs a new InputStreamReader on the InputStream in. Now character reading can be filtered through this InputStreamReader using the given character set.

Parameters:

in - the InputStream to convert to characters.

charset - the character set to use.

InputStreamReader

public InputStreamReader(InputStream in,
                         CharsetDecoder decoder)

Constructs a new InputStreamReader on the InputStream in. Now character reading can be filtered through this InputStreamReader using the given character set decoder.

Parameters:

in - the InputStream to convert to characters.

decoder - the character set ecoder to use.

Method Detail

close

public void close()
           throws IOException

Close this InputStreamReader. This implementation closes the source InputStream and releases all local storage.

Specified by:

close in interface Closeable

Specified by:

close in class Reader

Throws:

IOException - If an error occurs attempting to close this InputStreamReader.

getEncoding

public String getEncoding()

Answer the String which identifies the encoding used to convert bytes to characters. The value null is returned if this Reader has been closed.

Returns:

the String describing the converter or null if this Reader is closed.

read

public int read()
         throws IOException

Reads a single character from this InputStreamReader and returns the result as an int. The 2 higher-order characters are set to 0. If the end of reader was encountered then return -1. The byte value is either obtained from converting bytes in this readers buffer or by first filling the buffer from the source InputStream and then reading from the buffer.

Overrides:

read in class Reader

Returns:

the character read or -1 if end of reader.

Throws:

IOException - If the InputStreamReader is already closed or some other IO error occurs.

read

public int read(char[] buf,
                int offset,
                int length)
         throws IOException

Reads at most count characters from this Reader and stores them at offset in the character array buf. Returns the number of characters actually read or -1 if the end of reader was encountered. The bytes are either obtained from converting bytes in this readers buffer or by first filling the buffer from the source InputStream and then reading from the buffer.

Specified by:

read in class Reader

Parameters:

buf - character array to store the read characters

offset - offset in buf to store the read characters

length - maximum number of characters to read

Returns:

the number of characters read or -1 if end of reader.

Throws:

IOException - If the InputStreamReader is already closed or some other IO error occurs.

ready

public boolean ready()
              throws IOException

Answers a boolean indicating whether or not this InputStreamReader is ready to be read without blocking. If the result is true, the next read() will not block. If the result is false this Reader may or may not block when read() is sent. This implementation answers true if there are bytes available in the buffer or the source InputStream has bytes available.

Overrides:

ready in class Reader

Returns:

true if the receiver will not block when read() is called, false if unknown or blocking will occur.

Throws:

IOException - If the InputStreamReader is already closed or some other IO error occurs.