corbalist.java

卡内基美丽大学的网上教程 ssd8练习5答案

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

/**
* The item list for each client.
* 
* @author jack
* 
*/
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) && 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;
}
}