实验目标

本实验目标在实验 (2) 基础上，加入I/O流的操作，实现本地下载和上传文件的功能。可下载文件存放在磁盘 (笔者采用F盘) 的 uploadfile 文件夹，选择下载后可将指定文件下载至磁盘的 downloadfile文件夹中；选择上传则可将自己指定的文件上传至磁盘的 uploadfile 文件夹中。

同时新加入了 Doc 类，用于记录文件信息，用哈希表 docs 存储在DataProcessing类中，并加入了一系列对文件 Doc 信息增删的方法。

模块解析

首先新增加了 Doc 文件类：

改进后的模块结构图：

I/O层次结构体系：

源代码

本次实验代码基于实验 (2) 修改。

·DataProcessing

import java.sql.*;
import java.util.*;public class DataProcessing {private static boolean connectToDB = false;static Hashtable<String, User> users;static Hashtable<String, Doc> docs;    // 文件类哈希表static {users = new Hashtable<String, User>();users.put("jack", new Operator("jack", "123", "operator"));users.put("rose", new Browser("rose", "123", "browser"));users.put("kate", new Administrator("kate", "123", "administrator"));Init();// 获取当前时间Timestamp timestamp = new Timestamp(System.currentTimeMillis());docs = new Hashtable<String, Doc>();docs.put("0001", new Doc("0001", "jack", timestamp, "Doc Source Java", "Doc.txt"));    // 初始文件}public static void Init() {if (Math.random() > 0.2)connectToDB = true;elseconnectToDB = false;}// 查找文件public static Doc searchDoc(String ID) throws SQLException {if (docs.containsKey(ID)) {Doc temp = docs.get(ID);return temp;}return null;}// 获取所有文件public static Enumeration<Doc> getAllDocs() throws SQLException {Enumeration<Doc> e = docs.elements();return e;}// 增添新文件public static boolean insertDoc(String ID, String creator, Timestamp timestamp, String description, String filename)throws SQLException {Doc doc;if (docs.containsKey(ID))return false;else {doc = new Doc(ID, creator, timestamp, description, filename);docs.put(ID, doc);return true;}}public static User searchUser(String name) throws SQLException {if (!connectToDB)throw new SQLException("未连接到数据库！");double ranValue = Math.random();if (ranValue > 0.8)throw new SQLException("执行查询时出错！");if (users.containsKey(name)) {return users.get(name);}return null;}public static User searchUser(String name, String password) throws SQLException {if (!connectToDB)throw new SQLException("未连接到数据库！");double ranValue = Math.random();if (ranValue > 0.8)throw new SQLException("执行查询时出错！");if (users.containsKey(name)) {User temp = users.get(name);if ((temp.getPassword()).equals(password))return temp;}return null;}public static Enumeration<User> getAllUser() throws SQLException {if (!connectToDB)throw new SQLException("未连接到数据库！");double ranValue = Math.random();if (ranValue > 0.8)throw new SQLException("执行查询时出错！");Enumeration<User> e = users.elements();return e;}public static boolean updateUser(String name, String password, String role) throws SQLException {if (!connectToDB)throw new SQLException("未连接到数据库！");double ranValue = Math.random();if (ranValue > 0.8)throw new SQLException("执行更新时出错！");User user;if (users.containsKey(name)) {if (role.equalsIgnoreCase("administrator"))user = new Administrator(name, password, role);else if (role.equalsIgnoreCase("operator"))user = new Operator(name, password, role);else if (role.equalsIgnoreCase("browser"))user = new Browser(name, password, role);elsereturn false;users.put(name, user);return true;} elsereturn false;}public static boolean insertUser(String name, String password, String role) throws SQLException {if (!connectToDB)throw new SQLException("未连接到数据库！");double ranValue = Math.random();if (ranValue > 0.8)throw new SQLException("执行插入时出错！");User user;if (users.containsKey(name))return false;else {if (role.equalsIgnoreCase("administrator"))user = new Administrator(name, password, role);else if (role.equalsIgnoreCase("operator"))user = new Operator(name, password, role);else if (role.equalsIgnoreCase("browser"))user = new Browser(name, password, role);elsereturn false;users.put(name, user);return true;}}public static boolean deleteUser(String name) throws SQLException {if (!connectToDB)throw new SQLException("未连接到数据库！");double ranValue = Math.random();if (ranValue > 0.8)throw new SQLException("执行删除时出错！");if (users.containsKey(name)) {users.remove(name);return true;} elsereturn false;}public static void disconnectFromDB() throws SQLException {if (connectToDB) {if (Math.random() > 0.8) {throw new SQLException("断开数据库连接时出错！");}connectToDB = false;}}}

新增加 docs 哈希表，以及文件档案操作方法 searchDoc()、getAllDocs()、insertDoc()。

·Doc

import java.sql.Timestamp;public class Doc {private String ID;private String creator;private Timestamp timestamp;private String description;private String filename;public Doc(String ID, String creator, Timestamp timestamp, String description, String filename) {this.setID(ID);this.setCreator(creator);this.setTimestamp(timestamp);this.setDescription(description);this.setFilename(filename);}public String getID() {return ID;}public void setID(String iD) {ID = iD;}public String getCreator() {return creator;}public void setCreator(String creator) {this.creator = creator;}public Timestamp getTimestamp() {return timestamp;}public void setTimestamp(Timestamp timestamp) {this.timestamp = timestamp;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public String getFilename() {return filename;}public void setFilename(String filename) {this.filename = filename;}public String toString() {return "ID:" + this.ID + " Creator:" + this.creator + " Time:" + this.timestamp + " Filename:" + this.filename+ " Description:" + this.description;}}

Doc 类记录了档案文件的5类属性，需要注意 timestamp 记录的是文件创建时的时间，该成员属于 Timestamp 类。
因此在后续新增文件时，也要记得记录当前时间，作为其 timestamp 成员。

·User

import java.io.*;
import java.sql.SQLException;
import java.util.*;public abstract class User {private String name;private String password;private String role;// 上传与下载路径String uploadpath = "f:\\uploadfile\\";String downloadpath = "f:\\downloadfile\\";User(String name, String password, String role) {this.setName(name);this.setPassword(password);this.setRole(role);}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getRole() {return role;}public void setRole(String role) {this.role = role;}public abstract void showMenu();public String toString() {return "Name: " + this.name + " Password: " + this.password + " Role: " + this.role;}@SuppressWarnings("resource")public boolean downloadFile() {Scanner scan = new Scanner(System.in);System.out.print("请输入档案号：");String download_id = scan.next();Doc download_doc = null;try {download_doc = DataProcessing.searchDoc(download_id);} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}if (download_doc == null) {return false;} else {// 输入文件对象File input_file = new File(uploadpath + download_doc.getFilename());try {// 输入过滤器流,建立在文件流上BufferedInputStream input = new BufferedInputStream(new FileInputStream(input_file));// 输出文件对象File output_file = new File(downloadpath + download_doc.getFilename());// 创建文件output_file.createNewFile();// 输出过滤器流,建立在文件流上BufferedOutputStream output = new BufferedOutputStream(new FileOutputStream(output_file));// 用字节数组存取数据byte[] bytes = new byte[1024];// 文件写入操作int length = 0;while ((length = input.read(bytes)) != -1) {output.write(bytes, 0, length);}// 关闭流input.close();output.close();return true;} catch (FileNotFoundException e) {System.out.println(e.getLocalizedMessage());} catch (IOException e) {System.out.println(e.getLocalizedMessage());}return false;}}public void showFileList() {try {Enumeration<Doc> e = DataProcessing.getAllDocs();while (e.hasMoreElements()) {System.out.println(e.nextElement());}} catch (SQLException s) {System.out.println(s.getLocalizedMessage());}}public boolean changeSelfInfo(String password) {try {if (DataProcessing.updateUser(name, password, role)) {this.password = password;return true;} elsereturn false;} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}return false;}public void exitSystem() {System.out.println("系统退出, 谢谢使用 ! ");System.exit(0);}}

User 类增加了下载文件的具体操作，涉及 I/O 流的操作。
Java 的输入输出流类别有很多，操作写法也不唯一，这里就不对相关知识做详细讲解了，参考一下代码相信很容易理解。

·Administrator

import java.sql.SQLException;
import java.util.*;public class Administrator extends User {public Administrator(String name, String password, String role) {super(name, password, role);}public void updateUser(String input_name, String input_password, String input_role) {try {if (DataProcessing.updateUser(input_name, input_password, input_role)) {System.out.println("修改成功！");} else {System.out.println("修改失败！输入角色不正确！");}} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}}public void delUser(String input_name) {try {if (DataProcessing.deleteUser(input_name)) {System.out.println("删除成功！");} else {System.out.println("删除失败！查找不到用户名！");}} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}}public void addUser(String input_name, String input_password, String input_role) {try {if (DataProcessing.insertUser(input_name, input_password, input_role)) {System.out.println("添加成功！");} else {System.out.println("添加失败！用户名已存在/角色名不正确！");}} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}}public void listUser() {try {Enumeration<User> s = DataProcessing.getAllUser();while (s.hasMoreElements()) {System.out.println(s.nextElement());}} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}}@SuppressWarnings("resource")@Overridepublic void showMenu() {Scanner scan1 = new Scanner(System.in);Scanner scan2 = new Scanner(System.in);Scanner scan3 = new Scanner(System.in);Scanner scan4 = new Scanner(System.in);// 控制界面开关boolean administrator_isopen = true;// 记录用户选择String administrator_choice;while (administrator_isopen) {// 界面显示System.out.println("=======欢迎进入档案管理员菜单=======");System.out.println("            1.修改用户");System.out.println("            2.删除用户");System.out.println("            3.新增用户");System.out.println("            4.列出用户");System.out.println("            5.下载文件");System.out.println("            6.文件列表");System.out.println("            7.修改密码");System.out.println("            8.退    出");System.out.println("====================================");System.out.print("请输入选项：");administrator_choice = scan1.next();if (administrator_choice.equals("1")) {System.out.print("请输入用户名：");String input_name = scan2.next();System.out.print("请输入密码：");String input_password = scan3.next();try {if (DataProcessing.searchUser(input_name, input_password) != null) {System.out.print("请输入身份：");String input_role = scan4.next();this.updateUser(input_name, input_password, input_role);} else {System.out.println("用户名与密码不符！");}} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}} else if (administrator_choice.equals("2")) {System.out.print("请输入用户名：");String input_name = scan2.next();this.delUser(input_name);} else if (administrator_choice.equals("3")) {System.out.print("请输入用户名：");String input_name = scan2.next();System.out.print("请输入密码：");String input_password = scan3.next();System.out.print("请输入身份：");String input_role = scan4.next();this.addUser(input_name, input_password, input_role);} else if (administrator_choice.equals("4")) {this.listUser();} else if (administrator_choice.equals("5")) {if (super.downloadFile()) {System.out.println("下载成功！");} else {System.out.println("下载失败！");}} else if (administrator_choice.equals("6")) {super.showFileList();} else if (administrator_choice.equals("7")) {System.out.print("请输入新密码:");String newpassword = scan2.next();if (super.changeSelfInfo(newpassword)) {System.out.println("修改成功!");} else {System.out.println("修改失败");}} else if (administrator_choice.equals("8")) {administrator_isopen = false;} else {System.out.println("输入格式有误！请重新输入！");}}}
}

·Browser

import java.util.Scanner;public class Browser extends User {public Browser(String name, String password, String role) {super(name, password, role);}@SuppressWarnings("resource")@Overridepublic void showMenu() {Scanner scan1 = new Scanner(System.in);Scanner scan2 = new Scanner(System.in);// 控制界面开关boolean browser_isopen = true;// 记录用户选择String browser_choice;while (browser_isopen) {// 界面显示System.out.println("=======欢迎进入档案浏览员菜单=======");System.out.println("            1.下载文件");System.out.println("            2.文件列表");System.out.println("            3.修改密码");System.out.println("            4.退    出");System.out.println("====================================");System.out.print("请输入选项：");browser_choice = scan1.next();if (browser_choice.equals("1")) {if (super.downloadFile()) {System.out.println("下载成功！");} else {System.out.println("下载失败！");}} else if (browser_choice.equals("2")) {super.showFileList();} else if (browser_choice.equals("3")) {System.out.print("请输入新密码:");String newpassword = scan2.next();if (super.changeSelfInfo(newpassword)) {System.out.println("修改成功!");} else {System.out.println("修改失败");}} else if (browser_choice.equals("4")) {browser_isopen = false;} else {System.out.println("输入格式有误！请重新输入！");}}}}

·Operator

import java.io.*;
import java.sql.*;
import java.util.Scanner;public class Operator extends User {public Operator(String name, String password, String role) {super(name, password, role);}@SuppressWarnings("resource")public void uploadFile() {Scanner scan1 = new Scanner(System.in);Scanner scan2 = new Scanner(System.in);Scanner scan3 = new Scanner(System.in);System.out.print("请输入文件名(路径)：");String filename = scan1.next();System.out.print("请输入档案号：");String filenumber = scan2.next();try {if (DataProcessing.searchDoc(filenumber) != null) {System.out.println("档案号重复！");} else {System.out.print("请输入档案描述：");String fileDescription = scan3.next();// 输入文件对象File input_file = new File(filename);// 输入过滤器流,建立在文件流上BufferedInputStream input = new BufferedInputStream(new FileInputStream(input_file));// 输出文件对象File output_file = new File(uploadpath + input_file.getName());// 创建文件output_file.createNewFile();// 输出过滤器流,建立在文件流上BufferedOutputStream output = new BufferedOutputStream(new FileOutputStream(output_file));// 用字节数组存取数据byte[] bytes = new byte[1024];// 文件写入操作int length = 0;while ((length = input.read(bytes)) != -1) {output.write(bytes, 0, length);}// 关闭流input.close();output.close();DataProcessing.docs.put(filenumber, new Doc(filenumber, this.getName(),new Timestamp(System.currentTimeMillis()), fileDescription, input_file.getName()));System.out.println("上传成功！");}} catch (SQLException | IOException e) {System.out.println(e.getLocalizedMessage());}}@SuppressWarnings("resource")@Overridepublic void showMenu() {Scanner scan1 = new Scanner(System.in);Scanner scan2 = new Scanner(System.in);// 控制界面开关boolean operator_isopen = true;// 记录用户选择String operator_choice;while (operator_isopen) {// 界面显示System.out.println("=======欢迎进入档案录入员菜单=======");System.out.println("            1.上传文件");System.out.println("            2.下载文件");System.out.println("            3.文件列表");System.out.println("            4.修改密码");System.out.println("            5.退    出");System.out.println("====================================");System.out.print("请输入选项：");operator_choice = scan1.next();if (operator_choice.equals("1")) {this.uploadFile();} else if (operator_choice.equals("2")) {if (super.downloadFile()) {System.out.println("下载成功！");} else {System.out.println("下载失败！");}} else if (operator_choice.equals("3")) {super.showFileList();} else if (operator_choice.equals("4")) {System.out.print("请输入新密码:");String newpassword = scan2.next();if (super.changeSelfInfo(newpassword)) {System.out.println("修改成功!");} else {System.out.println("修改失败");}} else if (operator_choice.equals("5")) {operator_isopen = false;} else {System.out.println("输入格式有误！请重新输入！");}}}}

Operator 类内包含上传文件的操作，也涉及了I/O流。

·Main

import java.sql.SQLException;
import java.util.Scanner;public class Main {@SuppressWarnings("resource")public static void main(String[] args) {Scanner scan1 = new Scanner(System.in);Scanner scan2 = new Scanner(System.in);Scanner scan3 = new Scanner(System.in);// 控制界面开关boolean main_isopen = true;// 记录用户选择String main_choice;while (main_isopen) {// 界面显示System.out.println("=======欢迎进入档案系统=======");System.out.println("           1.登   录 ");System.out.println("           2.退   出 ");System.out.println("==============================");System.out.print("请输入选项：");main_choice = scan1.next();if (main_choice.equals("1")) {System.out.print("请输入用户名：");String input_name = scan2.next();System.out.print("请输入密码：");String input_password = scan3.next();User user;try {user = DataProcessing.searchUser(input_name, input_password);if (user == null) {System.out.println("用户名与密码不符！");} else {user.showMenu();}} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}} else if (main_choice.equals("2")) {try {// 断开连接DataProcessing.disconnectFromDB();main_isopen = false;} catch (SQLException e) {System.out.println(e.getLocalizedMessage());}} else {System.out.println("输入格式有误！请重新输入！");}}System.out.println("系统退出，感谢使用！");}}

写在最后

声明：本文内容来源于武汉理工大学2019-2020学年Java编程实验，仅供学习参考。如有不足错误地方，还请指出。
代码建议不要无脑抄 ，很多细节没有详细讲解，读者需自行理解。编程是实践练出来的，祝愿读者在编程之路上不断进步！