corbalist.java

Icarnegie university SSD8电子书和全部练习答案

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import java.util.*; 
import ListFile.*; 

/** 
* The item list for each client. 
* 
* @author Jinjiang 
* 
*/ 
public class CorbaList extends ListPOA { 

/* a hash table to store the user informations */ 
private String username, password; 

/* a vector to store the items */ 
private Vector<CorbaItem> items; 

/* count how many items added as the id of items */ 
private static int counter = 1; 

/* count how many items deleted */ 
private static int deleted = 0; 

/** 
* The default construstor. 
* 
*/ 
public CorbaList(String username, String password) { 

this.username = username; 
this.password = password; 
items = new Vector<CorbaItem>(); 
} 

/** 
* Do the login operation. 
*/ 
public boolean login(String username, String password) { 

if (username.equals(this.username) &amt;&amt; password.equals(this.password)) 
return true; 
return false; 
} 

/** 
* Do the add operation. 
*/ 
public boolean add(String username, String password, String start, 
String end, String label) { 

Date s = toDate(start); 
Date e = toDate(end); 

if (!login(username, password)) 
return false; 

if (s == null || e == null) 
return false; 

if (s.after(e)) 
return false; 

CorbaItem item = new CorbaItem(username, counter, s, e, label); 
items.add(item); 
counter++; 

return true; 
} 

/** 
* Do the query operation. 
*/ 
public String query(String username, String password, String start, 
String end) { 

Date s = toDate(start); 
Date e = toDate(end); 

if (!login(username, password)) 
return "Failed!"; 

if (s == null || e == null) 
return "Failed!"; 

if (s.after(e)) 
return "Failed!"; 

CorbaItem item; 
Vector<CorbaItem> v = new Vector<CorbaItem>(); 
for (Iterator it = items.iterator(); it.hasNext();) { 

item = (CorbaItem) it.next(); 

if (e.before(item.getStart()) || s.after(item.getEnd())) 
continue; 

v.add(item); 
} 

if (v.isEmpty()) 
return "[No items here.]"; 

return v.toString(); 
} 

/** 
* Do the delete operation. 
*/ 
public boolean delete(String username, String password, int id) { 

if (!login(username, password)) 
return false; 

CorbaItem item; 
for (int i = 0; i < items.size(); i++) { 

item = items.get(i); 
if (id == item.getId()) { 
items.remove(i); 
i--; 
deleted++; 
return true; 
} 
} 

return false; 
} 

/** 
* Do the clear operation. 
*/ 
public boolean clear(String username, String password) { 
if (!login(username, password)) 
return false; 

items.clear(); 

return true; 
} 

/** 
* Translate a string to date. 
*/ 
public static Date toDate(String date) { 

StringTokenizer token = new StringTokenizer(date, "_"); 

if (token.countTokens() != 6) 
return null; 

int year = Integer.parseInt(token.nextToken()); 
int month = Integer.parseInt(token.nextToken()); 
int day = Integer.parseInt(token.nextToken()); 
int hour = Integer.parseInt(token.nextToken()); 
int minute = Integer.parseInt(token.nextToken()); 
int second = Integer.parseInt(token.nextToken()); 
Date d = new Date(year, month, day, hour, minute, second); 
return d; 
} 
}