fileoperation.java

这是一个学校老师和学生的管理系统,程序比较简单,但是几乎所有功能都可以实现,如果想要用,只要再添加一些东西就可以了.

/**
 *******************************************************************************
 * FileOperation.java
 *
 * (c) Copyright 2008 Hewlett-Packard Development Company, L.P.
 *
 *<Program Content>
 *  System Name ： Students Management System
 *<Summarize>
 *  The file includes a FileOperation class and the class main function is to 
 *  operate the file.
 *<Update Record>
 *  2009-4-17    1.00    zhangliy
 *******************************************************************************
 */
package com.hp.eds.zhangliyuan.stuMan.util;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import com.hp.eds.zhangliyuan.stuMan.entity.UserInfo;
import com.hp.eds.zhangliyuan.stuMan.util.StringTool;

/**
 * The FileOperation class read data from the file and write the data to the
 * file.
 * 
 * @author zhangliy
 * @version 1.0
 */
public class FileOperation {

	/**
	 * read all information from CSV file and store them in a map.
	 * 
	 * @param fileName
	 *            -the name of the CSV file which contents will be fetched
	 * @return Map:the map that includes all information of the file;if the file
	 *         doesn't exist,return null
	 */
	public static Map<String, UserInfo> readFile(String fileName) {
		if (StringTool.isStringEmpty(fileName)) {
			// the fileName is empty			
			return null;
		}
		// declare a FileReader object
		FileReader fileR = null;
		// declare a FileReader object
		BufferedReader bufferedR = null;
		// create a Map object to receive one property from the file
		Map<String, UserInfo> map = new HashMap<String, UserInfo>();
		try {
			// create a actual FileReader object
			fileR = new FileReader(fileName);
			// create a actual BufferedReader object
			bufferedR = new BufferedReader(fileR);
			bufferedR.readLine();
			// read a line from the file
			String string = bufferedR.readLine();
			while (string != null) {
				// the line is not null
				String[] strings = string.split(",", -1);
				// create a user object
				UserInfo user = new UserInfo();
				user.setStuId(strings[0]);				
				user.setStuName(strings[1]);
				user.setPassword(strings[2]);
				user.setHometown(strings[3]);
				user.setSex(strings[4]);
				user.setTelephone(strings[5]);
				user.setEmail(strings[6]);
				// put key and value into the map
				map.put(strings[1], user);
				// read a new line
				string = bufferedR.readLine();
			}

			if (map == null || map.size() == 0) {
				// the map is empty
				return null;
			}
			// the map is not empty,return list
			return map;
		} catch (FileNotFoundException fileExc) {
			// display the exception informaiton
			System.out.println("Catch FileNotFoundException");
			// print the information about the FileNotFoundException
			fileExc.printStackTrace();
		} catch (IOException ioExc) {
			// display the exception informaiton
			System.out.println("Catch IOException");
			// print the information about the IOException
			ioExc.printStackTrace();
		} finally {
			try {
				if (bufferedR != null) {
					// bufferedR is not null,close the file
					bufferedR.close();
				}
			} catch (IOException ioExc) {
				// display the exception informaiton
				System.out.println("Catch IOException");
				// print the information about the IOException
				ioExc.printStackTrace();
			}
		}
		// there is something wrong with the program,return null
		return null;
	}

	/**
	 * according the key to fetch the value of the property from the file
	 * 
	 * @param fileName
	 *            -the file name
	 * 
	 * @param key
	 *            -the key of an user in the file
	 * 
	 * @return User the value of the map;if there is no user whose key is equal
	 *         to the key which has been given,return null
	 */
	public static UserInfo fetchValue(String fileName, String key) {
		Map map = readFile(fileName);
		if (map == null) {
			// the list is empty			
			return null;
		}
		Set set = map.keySet();
		Iterator iter = set.iterator();
		while (iter.hasNext()) {
			String keyValue = (String) iter.next();			
			if (keyValue.equals(key)) {
				// he key of current map is equal to the key given,return the
				// value of the current
				UserInfo user = (UserInfo) map.get(keyValue);
				return user;
			} else {
				// the key of current map doesn't equal to the key given,go on
				// searching
				continue;
			}
		}
		// there is no property whose key is equal to the key which has been
		// given,return null
		return null;
	}

	/**
	 * write information to a CSV file.
	 * 
	 * @param map
	 *            -the map includes all information need to write
	 * 
	 * @param fileName
	 *            -the file where imformation will be writed
	 */
	public static void writeFile(Map<String, UserInfo> map, String fileName) {
		// declare a file
		File file = null;
		// declare a FileWriter
		FileWriter fileWrite = null;
		// declare a BufferedWriter
		BufferedWriter bufferedWrite = null;
		// crate a new object of User
		UserInfo user = new UserInfo();

		try {
			Set set = map.keySet();
			// the iterator of the dogs List
			Iterator iter = set.iterator();
			// create an actual file
			file = new File(fileName);
			// create a actual FileWriter object
			fileWrite = new FileWriter(file);
			// create a BufferedWriter object
			bufferedWrite = new BufferedWriter(fileWrite);

			// write the user's properties into the file
			bufferedWrite
					.write("stuId,stuName,password,hometown,sex,telephone,email");
			// write a new line
			bufferedWrite.newLine();

			// write information to the file
			while (iter.hasNext()) {
				// get current Dog object
				String key = (String) iter.next();
				user = (UserInfo) map.get(key);

				// write the user'a information to the file
				bufferedWrite.write(user.getStuId() + "," + user.getStuName()
						+ "," + user.getPassword() + "," + user.getHometown()
						+ "," + user.getSex() + "," + user.getTelephone() + ","
						+ user.getEmail());

				bufferedWrite.newLine();
			}
			// flush before closing
			bufferedWrite.flush();
		} catch (IOException ioe) {
			// display the exception informaiton
			System.out.println("Catch IOException");
			// print the information about the IOException
			ioe.printStackTrace();
		} finally {
			try {
				// close file when done
				bufferedWrite.close();
			} catch (IOException ioe) {
				// display the exception informaiton
				System.out.println("It can not be closed!");
				// print the information about the IOException
				ioe.printStackTrace();
			}
		}

	}
}