dimbrowser.java

这是一个分布式通信程序框架源程序

package dim;

public class DimBrowser
{
	static DimInfo answerSrvc;
	static DimLock dimLock;
	static String answer;
	static String[] allServices;
	
    private DimBrowser()// we do not allow instantiation of this class
    {
    	answerSrvc = null;
    	dimLock = null;
    	allServices = null;
    } 

    public static synchronized String[] getServices(String pattern)
    {
	   	if(dimLock == null)
			dimLock = new DimLock();
		dimLock.reset();		
     	if(answerSrvc == null)
    	{
			answerSrvc = new DimUpdatedInfo("DIS_DNS/SERVICE_INFO/RpcOut","__DIM_NO_LINK__")
			{
				public void infoHandler()
				{
					answer = getString();
					if(answer.compareTo("__DIM_NO_LINK__") == 0)
					{
						answer = "";
					}
					else
					{
					}
					dimLock.dimWakeUp();
				}
			};
    	}
   		DimClient.sendCommand("DIS_DNS/SERVICE_INFO/RpcIn", pattern);
		dimLock.dimWait();
		if(answer.length() != 0)
		{
			allServices = answer.split("\n");
		}
		else
		{
			allServices = new String[0];
		}
		String[] services = new String [allServices.length];
		for(int i = 0; i < allServices.length;i++)
		{
			int index = allServices[i].indexOf('|');
			services[i] = allServices[i].substring(0,index);
		}
		return services;
    }
    public static synchronized boolean isCommand(String service)
    {
		int index = findService(service);
		if(index == -1)
			return false;
		int i = allServices[index].lastIndexOf('|');
		if(allServices[index].substring(i+1).compareTo("CMD") == 0)
			return true;
		return false;
    }
	public static synchronized String getFormat(String service)
	{
		int index = findService(service);
		if(index == -1)
			return null;
		int i = allServices[index].indexOf('|');
		int j = allServices[index].lastIndexOf('|');
		String format = allServices[index].substring(i+1,j);
		return format;
	}
    private static int findService(String service)
    {
		for(int i = 0; i < allServices.length;i++)
		{
			int index = allServices[i].indexOf('|');
			if(service.compareTo(allServices[i].substring(0,index)) == 0)
				return i;
		}
		return -1;    	
    }
	public static void stopBrowsing()
	{
		answerSrvc.releaseService();
	}
}

class DimLock
{
	int n = 0;
	public DimLock()
	{
		n = 0;
	}
	public synchronized void reset()
	{
		n = 0;
	}
	public synchronized void dimWait()
	{
		if(n == 0)
		{
			try{
				wait();
			}catch (InterruptedException e){}
		}			
	}
	public synchronized void dimWakeUp()
	{
		n++;
		notify();
	}
}