org.wings.io
Class GZIPCompressingDevice

java.lang.Object
  org.wings.io.GZIPCompressingDevice

All Implemented Interfaces:

Device

public final class GZIPCompressingDevice
extends Object
implements Device

A Device encapsulating an OutputStream, compressing its output. You can use this, if the browser states, that it can handle compressed data; don't forget to set the appropriate header, then (Content-Encoding). Override DeviceFactory and declare the updated factory in web.xml to use other devices.

Example Draft

String mimeType = extInfo.getMimeType();
 // some browsers can handle a gziped stream only for text-files.
 if (mimeType != null && mimeType.startsWith("text/")) {
 String acceptEncoding = req.getHeader("Accept-Encoding");
 int gzipPos;
 if (acceptEncoding != null
 && (gzipPos = acceptEncoding.indexOf("gzip")) >= 0) {
 // some browsers send 'x-gzip', others just 'gzip'. Our
 // response should be the same.
 boolean isXGZip = (gzipPos >= 2
 && acceptEncoding.charAt(gzipPos-1) == '-'
 && acceptEncoding.charAt(gzipPos-2) == 'x');
 response.addHeader("Content-Encoding",
 (isXGZip ? "x-gzip" : "gzip"));
 return new GZIPCompressingDevice(response.getOutputStream());
 }
 }
 return new ServletDevice(response.getOutputStream());
 }
 

Author:

Henner Zeller

Constructor Summary

GZIPCompressingDevice(Device d)

GZIPCompressingDevice(OutputStream out)

Method Summary

void	close() close the Device.
void	flush() Flush this Device.
boolean	isSizePreserving() this returns false, since the compressing device is not size preserving.
Device	print(char c) Print a character.
Device	print(char[] c) Print a character array.
Device	print(char[] c, int start, int len) Print len characters from the specified char array starting at offset off to this Device.
Device	print(int i) Print an integer.
Device	print(Object o) Print any Object
Device	print(String s) Print a String.
Device	write(byte[] b) Writes b.length bytes from the specified byte array to this output stream.
Device	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this Device.
Device	write(int c) Writes the specified byte to this data output stream.

Methods inherited from class java.lang.Object

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

Constructor Detail

GZIPCompressingDevice

public GZIPCompressingDevice(OutputStream out)
                      throws IOException

Throws:

IOException

GZIPCompressingDevice

public GZIPCompressingDevice(Device d)
                      throws IOException

Throws:

IOException

Method Detail

isSizePreserving

public boolean isSizePreserving()

this returns false, since the compressing device is not size preserving. Thats what is all about, right ?

Specified by:

isSizePreserving in interface Device

Returns:

'true', if this device leaves the size of the data going through it, untouched. This is usually true.

flush

public void flush()
           throws IOException

Description copied from interface: Device

Flush this Device.

Specified by:

flush in interface Device

Throws:

IOException

close

public void close()
           throws IOException

Description copied from interface: Device

close the Device.

Specified by:

close in interface Device

Throws:

IOException

print

public Device print(char c)
             throws IOException

Description copied from interface: Device

Print a character.

Specified by:

print in interface Device

Throws:

IOException

print

public Device print(char[] c)
             throws IOException

Description copied from interface: Device

Print a character array.

Specified by:

print in interface Device

Throws:

IOException

print

public Device print(char[] c,
                    int start,
                    int len)
             throws IOException

Description copied from interface: Device

Print len characters from the specified char array starting at offset off to this Device.

Specified by:

print in interface Device

Throws:

IOException

print

public Device print(String s)
             throws IOException

Description copied from interface: Device

Print a String.

Specified by:

print in interface Device

Throws:

IOException

print

public Device print(int i)
             throws IOException

Description copied from interface: Device

Print an integer.

Specified by:

print in interface Device

Throws:

IOException

print

public Device print(Object o)
             throws IOException

Description copied from interface: Device

Print any Object

Specified by:

print in interface Device

Throws:

IOException

write

public Device write(int c)
             throws IOException

Description copied from interface: Device

Writes the specified byte to this data output stream.

Specified by:

write in interface Device

Throws:

IOException

write

public Device write(byte[] b)
             throws IOException

Description copied from interface: Device

Writes b.length bytes from the specified byte array to this output stream.

Specified by:

write in interface Device

Throws:

IOException

write

public Device write(byte[] b,
                    int off,
                    int len)
             throws IOException

Description copied from interface: Device

Writes len bytes from the specified byte array starting at offset off to this Device.

Specified by:

write in interface Device

Throws:

IOException