ZK - Open Source Ajax Java Framework

package j1pj6m23$v3;
import java.util.LinkedList;
import java.util.concurrent.atomic.AtomicInteger;
import org.zkoss.zk.ui.Component;
import org.zkoss.zk.ui.Desktop;
import org.zkoss.zk.ui.Executions;
import org.zkoss.zk.ui.Page;
import org.zkoss.zk.ui.ext.Scope;
import org.zkoss.zk.ui.sys.IdGenerator;
/**
 * 
 * @author Ian Tsai (zanyking)
 *
 */
public class ConsistentIdGenerator implements IdGenerator {
	private static final AtomicInteger DESKTOP_ID_AINT = new AtomicInteger();
	private final IdGenerator innerIdGenerator;
	/**
	 * key="USE_TEST_COMP_UUID_GENERATOR", valueType=boolean 
	 */
	public ConsistentIdGenerator(){
		String useTesting = System.getProperty("USE_TEST_COMP_UUID_GENERATOR");
		Boolean isUnderTesting = Boolean.FALSE;
		if(useTesting!=null){
			try{
				isUnderTesting = Boolean.parseBoolean(useTesting);
			}catch(Exception e){
				//ignore, nothing need to do. 
			}
		}
		if(isUnderTesting){
			innerIdGenerator = new TestingIdGenerator();
		}else{
			innerIdGenerator = new ProductionIdGenerator();
		}
	}
	public String nextComponentUuid(Desktop arg0, Component arg1) {
		return innerIdGenerator.nextComponentUuid(arg0, arg1);
	}
	public String nextDesktopId(Desktop arg0) {
		return innerIdGenerator.nextDesktopId(arg0);
	}
	public String nextPageUuid(Page arg0) {
		return innerIdGenerator.nextPageUuid(arg0);
	}
	
	private static final String CHAR = "0123456789abcdefghijklmnopqrstuvwxyz";
	private static final char[] CHAR_ARR =CHAR.toCharArray();
	private static String encodeRadix36(int in){
		StringBuffer sb = new StringBuffer(4);
		// almost impossible for a desktop to contain more than 10,000 components.
		int inp = in,k,i;
		do{
			k = inp /CHAR_ARR.length;
			i = inp % CHAR_ARR.length;
			sb.append(CHAR_ARR[i]);
			inp = k;
		}
		while(k>0);
		
		return sb.reverse().toString();
	}
	
	private static int getAndIncrement(Scope scope, String key){
		AtomicInteger aInt = (AtomicInteger) scope.getAttribute(key);
		if (aInt == null) {
			scope.setAttribute(key, aInt = new AtomicInteger());
		}
		int i = aInt.getAndIncrement();
		return i;
	}
	
	/**
	 * 
	 * @author Ian Tsai(ytsai1)
	 *
	 */
	static class ProductionIdGenerator implements IdGenerator{
		private final static String ID_NUMBER = "zk_id_num";
		
		public String nextComponentUuid(Desktop desktop, Component comp) {
			String key = ID_NUMBER + comp.getClass().getSimpleName();
			int i = getAndIncrement(desktop, key);
			String compId = "zc_" + comp.getClass().getSimpleName() +"_"+ i;
			return compId;
		}
		public String nextDesktopId(Desktop desktop) {
			int i = DESKTOP_ID_AINT.getAndIncrement();
			String dtid = "Desktop_" + i;
			((javax.servlet.http.HttpServletResponse)Executions.getCurrent().getNativeResponse()).setHeader("Desktop", dtid);
			return dtid;
		}
		public String nextPageUuid(Page page) {
			return null;
		}
	}//end of class
	/**
	 * 
	 * @author Ian Tsai(ytsai1)
	 *
	 */
	static class TestingIdGenerator implements IdGenerator{
		private static final String KEY_GENERIC_SHORT_NAME = "KEY_GENERIC_SHORT_NAME";
		private final static String KEY_UUID_ATOMIC_INT = "KEY_UUID_ATOMIC_INT";
		/*
		 * (non-Javadoc)
		 * @see org.zkoss.zk.ui.sys.IdGenerator#nextComponentUuid(org.zkoss.zk.ui.Desktop, org.zkoss.zk.ui.Component)
		 */
		public String nextComponentUuid(Desktop desktop, Component comp) {
			
			Page page = comp.getPage();
			Scope scope = page==null? desktop : page;
			String pageUuid = page==null? "pseudo_page" : page.getUuid();
			
			String prefix = enc(comp.getClass().getSimpleName(), 
					enc(pageUuid, "zc_", desktop, false), desktop, false);
			
			String uuid = prefix + encodeRadix36(getAndIncrement(scope, KEY_UUID_ATOMIC_INT));
	       
			return uuid;
		}
		
		/*
		 * (non-Javadoc)
		 * @see org.zkoss.zk.ui.sys.IdGenerator#nextDesktopId(org.zkoss.zk.ui.Desktop)
		 */
		public String nextDesktopId(Desktop desktop) {
			int i = DESKTOP_ID_AINT.getAndIncrement();
			String dtid = "Desktop_" + i;
			((javax.servlet.http.HttpServletResponse)Executions.getCurrent().getNativeResponse()).setHeader("Desktop", dtid);
			return dtid;
		}
		/*
		 * (non-Javadoc)
		 * @see org.zkoss.zk.ui.sys.IdGenerator#nextPageUuid(org.zkoss.zk.ui.Page)
		 */
		public String nextPageUuid(Page page) {
			return null;
		}
		/**
		 * 
		 * @param name
		 * @param prefix
		 * @param scope
		 * @return
		 */
		private static String enc(String name, String prefix, Scope scope, boolean disable){
			if(disable){
				return prefix+name+"_";
			}
			StatefulIdEncoder idEncoder = (StatefulIdEncoder) scope.getAttribute(KEY_GENERIC_SHORT_NAME);
			
			if (idEncoder == null) {
				scope.setAttribute(KEY_GENERIC_SHORT_NAME, 
						idEncoder = new StatefulIdEncoder());
			}
			return prefix+idEncoder.encode(name)+"_";
		}
		
		/**
		 * @author ytsai1
		 */
		private static class StatefulIdEncoder{
			final LinkedList<String> store = new LinkedList<String>();
			/**
			 * @param name
			 * @return
			 */
			public String encode(String name){
				if(name==null || name.isEmpty())
					throw new IllegalArgumentException("StatefulIdEncoder can't encode a null or empty String: "+name);
				int counter = 0;
				int idx = -1;
				for(String temp : store){
					if(temp.equals(name)){
						idx = counter;
						break;
					}
					counter++;
				}
				if(idx<0){//if not exist
					store.add(name);
					return encodeRadix36(counter); 
				}else{// it's exist
					return encodeRadix36(idx);	
				}
			}
		}
	}//end of class...
}

<zk>
  <window border="normal" title="hello" >
  	
  	<div>It's impossible to demonstrat the effect in Fiddle, please copy the code to your project and use it.</div>
  	
    
    
  </window>
</zk>