borrower.java

线程通信

import java.util.*;
public class Borrower extends StringAdapter{
	static int Id=0; 
	
	private int id=Id++;
	private List borrowBook=new ArrayList();// book borrowed

	
	
	
	public void borrow(Book b)throws LibraryException{
		boolean success=false;
		try{	
			success=b.borrow(this.id);
		}finally{
			if(success)
				borrowBook.add(b);
			else
				throw new LibraryException(" currently unavaliable");
		}
		//although no deadlock danger need to keep the data in pace
		//eg: when another ClientGUI run on the same borrower for checkloan()
		//will produce data interference
		//althernative is to synchronize on borrower
	}
	
	public void retun(Book b)throws LibraryException{
		boolean success=false;
		try{
			success=b.retun(this.id);
		}finally{
			if(success)
				borrowBook.remove(b);
			else
				throw new LibraryException(" currently not borrowing");
		}
	}
	
	
	public String checkLoan(){
		String s="loan:\n"
		+(adapt("bookid",20)+adapt("title",21)+adapt("borrower",23))+"\n";
		
		for(int i=0;i<borrowBook.size();i++)
			s+=borrowBook.get(i).toString()+"\n";
		return s;
	}
	
	
	public String getId(){
		return Integer.toString(id);
	}
		 
}