Bug 82804 Jar creation should use less memory
I noticed that the JarWriter will read the entire file it plans to store into memory. An optimization would be to stream the file directly into the JarOutputStream. The only catch is with STORED items which need the CRC32 computed. A penalty could be taken in that case to compute the CRC in a loop and then stream the file.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/jarpackager/JarPackageData.java
fGenerateManifest= state;
	}
	
	/**
	 * Tells whether the manifest file must be saved to the 
	 * specified file during the export operation.
	 * 
	 * @return	<code>true</code> if the manifest must be saved
	 * @see #getManifestLocation()
	 */
	public boolean isManifestSaved() {
		return fSaveManifest;
	}
	/**
	 * Sets whether the manifest file must be saved during export
	 * operation or not.
	 * 
	 * @param state the new state
	 * @see #getManifestLocation()
	 */
	public void setSaveManifest(boolean state) {
		fSaveManifest= state;
		if (!fSaveManifest)
			
			setReuseManifest(false);
	}
	/**
	 * Tells whether a previously generated manifest should be reused.
	 * 
	 * @return	<code>true</code> if the generated manifest will be reused when regenerating this JAR,