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
* Sealing: a JAR can be
	 * - sealed (fSealJar is true) and a list of 
	 *		unsealed packages can be defined (fPackagesToUnseal)
	 *		while the list of sealed packages is ignored
	 * - unsealed (fSealJar is false) and the list of
	 *		sealed packages can be defined (fPackagesToSeal)
	 *		while the list of unsealed packages is ignored
	 */
	private boolean fSealJar;
	private IPackageFragment[] fPackagesToSeal;
	private IPackageFragment[] fPackagesToUnseal;
 	private IType fManifestMainClass;
 	
 	private String fComment; 
	/*
	 * Error handling
	 */
	private boolean fExportErrors;
	private boolean fExportWarnings;
	
	
	private IManifestProvider fManifestProvider;
	
	
	private boolean fIncludeDirectoryEntries;
	
	public JarPackageData() {
		setExportClassFiles(true);
		setExportOutputFolders(false);
		setUseSourceFolderHierarchy(false);