Java面向对象与多线程综合实验（二）之 异常处理

其他 2018-12-11 01:50:14 阅读次数: 0

理解异常的基本概念；了解Java异常的层次结构；熟悉并掌握Java异常的捕获处理方法。
（1）阅读Java™ Platform, Standard Edition 8 API Specification文档，了解后续编程中将要处理的IOException及其子类FileNotFoundException、EOFException，SocketException，SQLException以及运行时异常RuntimeException与其子类IllegalStateException。

（2）根据新提供的DataProcessing类（因还未讲SQL，此类模拟异常出现情况，以一定概率随机产生异常），在所编写的Administrator、Operator和Browser类，增加异常处理功能。

  • User.java

import java.sql.SQLException;
import java.io.IOException;
public abstract class User {
     private String name;
     private String password;
     private String role;
     User(String name,String password,String role){
    	 this.name=name;
    	 this.password=password;
    	 this.role=role;
     }
     public abstract  void showMenu();
     public void showFileList() throws SQLException{
    	 double ranValue=Math.random();
    	 if(ranValue>0.5) throw new SQLException("Error in accessing file DB");
    	 System.out.println("列表……");
     }
     public boolean downloadFile() throws IOException{
    	 double ranValue=Math.random();
    	 if(ranValue>0.5) throw new IOException("Error in accessing file");
    	 System.out.println("下载文件……");
    	 return true;
     }
     public boolean changeSelfInfo(String password) throws SQLException{
    	if(DataProcessing.update(name,password,role)) {
    		this.password=password;
    		System.out.println("修改成功！");
    		return true;
    	}
    	else {
    		System.out.println("修改失败！");
    		return false;
    	}
     }
     public void exitSystem() {
    	 System.out.println("系统退出，谢谢使用！");
    	 System.exit(0);
     }
     public void setName(String name) {
    	 this.name=name;
     }
     public String getName() {
    	 return name;
     }
     public void setPassword(String password) {
    	 this.password=password;
     }
     public String getPassword() {
    	 return password;
     }
     public void setRole(String role) {
    	 this.role=role;
     }
     public String getRole() {
    	 return role;
     }
}

  • DataProcessing.java

import java.util.Enumeration;
import java.util.Hashtable;
import java.sql.*;

public class DataProcessing {
	private static boolean connectToDB=false;
    static Hashtable<String,User> users;
    static {
    	users=new Hashtable<String,User>();
    	users.put("hjy", new Operator("hjy","111","operator"));
    	users.put("cr", new Browser("cr","000","browser"));
    	users.put("myk", new Administrator("myk","250","administrator"));
    	Init();
    }
    public static void Init() {
    	//connect to database
   
    	//update database connection status
    	if(Math.random()>0.2) connectToDB=true;
    	else connectToDB=false;
    }
    public static User searchUser(String name) throws SQLException{
    	if(!connectToDB) throw new SQLException("Not Connected to Database");
    	double ranValue=Math.random();
    	if(ranValue>0.5) throw new SQLException("Error in excecuting Query");
    	if(users.containsKey(name)) {
    		return users.get(name);
    	}
    	return null;
    }
    public static User search(String name,String password) throws SQLException{
    	if(!connectToDB) throw new SQLException("Not Connected to Database");
    	double ranValue=Math.random();
    	if(ranValue>0.5) throw new SQLException("Error in excecuting Query");
    	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("Not Connected to Database");
    	double ranValue=Math.random();
    	if(ranValue>0.5) throw new SQLException("Error in excecuting Query");
    	Enumeration<User> e=users.elements();
    	return e;
    }
    public static boolean update(String name,String password,String role) throws SQLException{
    	User user;
    	if(!connectToDB) throw new SQLException("Not Connected to Database");
    	double ranValue=Math.random();
    	if(ranValue>0.5) throw new SQLException("Error in excecuting Query");
    	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
    			user=new Browser(name,password,role);
    		users.put(name, user);
    		return true;
    	}
    	else return false;
    }
    public static boolean insert(String name,String password,String role) throws SQLException{
    	User user;
    	if(!connectToDB) throw new SQLException("Not Connected to Database");
    	double ranValue=Math.random();
    	if(ranValue>0.5) throw new SQLException("Error in excecuting Query");
    	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
    			user=new Browser(name,password,role);
    		users.put(name, user);
    		return true;
    	}
    }
    public static boolean delete(String name) throws SQLException{
    	if(!connectToDB) throw new SQLException("Not Connected to Database");
    	double ranValue=Math.random();
    	if(ranValue>0.5) throw new SQLException("Error in excecuting Query");
    	if(users.containsKey(name)) {
    		users.remove(name);
    		return true;
    	}
    	else return false;
    }
    public void disconnectFromDB() {
    	if(connectToDB) {
    		//close Statement and Connection
    		try {
    			if(Math.random()>0.5) throw new SQLException("Error in disconnecting DB");
    		}
    		catch(SQLException sqlException) {
    			sqlException.printStackTrace();
    		}finally {
    			connectToDB=false;
    		}
    	}
    }
}

  • Administrator.java

import java.io.IOException;
import java.sql.SQLException;
import java.util.Enumeration;
import java.util.Scanner;
public class Administrator extends User{
	private Scanner sc;
    Administrator(String name, String password, String role) {
		super(name, password, role);
	}
	public void changeUserInfo() {
		System.out.println("请输入要修改的用户姓名:");
    	String cn=sc.next();
    	System.out.println("请输入新的用户密码:");
    	String cm=sc.next();
    	System.out.println("请输入新的用户角色:");
    	String cr=sc.next();
    	try {
			if(DataProcessing.update(cn, cm, cr)) {
				System.out.println("修改用户信息成功！");
			}
			else System.out.println("修改失败！");
		} 
    	catch (SQLException e) {
    		System.out.println("文件访问错误"+e.getMessage());
		}
     }
    public void delUser() {
    	System.out.println("请输入要删除的用户姓名:");
    	String dn=sc.next();
    	try {
			if(DataProcessing.delete(dn)) {
				System.out.println("删除成功！");
			}
			else System.out.println("删除失败！该用户不存在");
		} 
    	catch (SQLException e) {
    		System.out.println("文件访问错误"+e.getMessage());
		}
    }
    public void addUser() {
    	System.out.println("请输入要增加的用户姓名:");
    	String an=sc.next();
    	System.out.println("请输入要增加的用户密码:");
    	String am=sc.next();
    	System.out.println("请输入要增加的用户角色:");
    	String ar=sc.next();
    	try {
			if(DataProcessing.insert(an, am, ar)) {
				System.out.println("增加用户"+an+"成功！");
			}
			else System.out.println("增加用户"+an+"失败！");
		} 
    	catch (SQLException e) {
    		System.out.println("文件访问错误"+e.getMessage());
		}
    	
    }
    public void listUser() {
    	 Enumeration<User> e = null;
		try {
			e = DataProcessing.getAllUser();
		} 
		catch (SQLException e1) {
			System.out.println("文件访问错误"+e1.getMessage());
		}
    	 User user;
    	 while(e.hasMoreElements()) {
    		 user=e.nextElement();
    		 System.out.println("姓名："+user.getName()+"密码："+user.getPassword()+"角色："+user.getRole());
    	 }
    }
	public void showMenu() {
		System.out.println("欢迎进入档案操作员菜单！");
    	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(本人)密码");
    	System.out.println("8.退出");
    	sc=new Scanner(System.in);
    	int i=sc.nextInt();
    	switch(i) {
    	    case 1:{
    	    	changeUserInfo();
	    	    break;
    	    }
    	    case 2:{
	            delUser();
	            break;
    	    }
    	    case 3:{
    	        addUser();
    	    	break;
        	}
    	    case 4:{
    	        listUser();
    	        break;
        	}
    	    case 5:{
    	    	try {
					downloadFile();
				} 
    	    	catch (IOException e) {
					// TODO Auto-generated catch block
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 6:{
    	    	try {
					showFileList();
				} 
    	    	catch (SQLException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 7:{
    	    	System.out.println("请输入新密码：");
    	    	String psd=sc.next();
    	    	try {
					changeSelfInfo(psd);
				} 
    	    	catch (SQLException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 8:{
    	    	exitSystem();
    	    }
    	    default:{
    	    	System.out.println("输入非法！请重新输入！");
    	    	break;
    	    }
    	}
    	showMenu();
	}
}

  • Operator.java

import java.io.IOException;
import java.sql.SQLException;
import java.util.Scanner;

public class Operator extends User{
	Operator(String name, String password, String role) {
		super(name, password, role);
	}
    public void showMenu() {
    	System.out.println("欢迎进入档案操作员菜单！");
    	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");
    	@SuppressWarnings("resource")
		Scanner sc = new Scanner(System.in);
    	int i=sc.nextInt();
    	switch(i) {
    	    case 1:{
    	        uploadFile();
    	        break;
        	}
    	    case 2:{
    	    	try {
					downloadFile();
				} 
    	    	catch (IOException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 3:{
    	    	try {
					showFileList();
				} 
    	    	catch (SQLException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 4:{
    	    	System.out.println("请输入新密码：");
    	    	String psd=sc.next();
    	    	try {
					changeSelfInfo(psd);
				} 
    	    	catch (SQLException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 5:{
    	    	exitSystem();
    	    }
    	    default:{
    	    	System.out.println("输入非法！请重新输入！");
    	    	break;
    	    }
    	}
    	showMenu();
    }
    public void uploadFile() {
    	//上传文件
    	System.out.println("上传成功！");
    }
}

  • Browser.java

import java.io.IOException;
import java.sql.SQLException;
import java.util.Scanner;
public class Browser extends User{
	Browser(String name, String password, String role) {
		super(name, password, role);
	}
	public void showMenu() {
    	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.print("请选择：");
    	@SuppressWarnings("resource")
		Scanner sc = new Scanner(System.in);
    	int i=sc.nextInt();
    	switch(i) {
    	    case 1:{
    	    	try {
					downloadFile();
				} 
    	    	catch (IOException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 2:{
    	    	try {
					showFileList();
				} 
    	    	catch (SQLException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 3:{
    	    	System.out.println("请输入新密码：");
    	    	String psd=sc.nextLine();
    	    	try {
					changeSelfInfo(psd);
				} 
    	    	catch (SQLException e) {
    	    		System.out.println("文件访问错误"+e.getMessage());
				}
    	    	break;
    	    }
    	    case 4:{
    	    	exitSystem();
    	    }
    	    default:{
    	    	System.out.println("输入非法！请重新输入！");
    	    	break;
    	    }
    	}
    	showMenu();
    }
}

  • Main.java

import java.sql.SQLException;
import java.util.Scanner;
public class Main {
    public static void main(String args[]){
    	while(true) {
        	System.out.println("欢迎进入档案管理系统！");
        	System.out.println("1.登录");
        	System.out.println("2.退出");
			@SuppressWarnings("resource")
			Scanner sc=new Scanner(System.in);
        	int i=sc.nextInt();
        	if(i==1) {
        		System.out.println("请输入用户名：");
        		String name=sc.next();
        		try {
					if(DataProcessing.searchUser(name)!=null) {
						System.out.println("请输入密码：");
						String password=sc.next();
						try {
						    if(DataProcessing.search( name ,password)!=null)
						        DataProcessing.search(name, password).showMenu();
						    else System.out.println("密码错误！");  
						}
						catch(SQLException e) {
							System.out.println("数据库错误"+e.getMessage());
						}
					}
					else {
					   System.out.println("用户不存在！");   
					}
				} 
        		catch (SQLException e) {
        			System.out.println("数据库错误"+e.getMessage());
				}
            }
        	else if(i==2) {
        		System.exit(0);
        	}
        	else {
        		System.out.println("输入非法！请重新输入。");
        	}
    	}
    }
}

以下是需要完成的结果展示：Java面向对象与多线程综合实验（二）之 异常处理

猜你喜欢

转载自blog.csdn.net/m0_37650503/article/details/84439390
今日推荐
火速冲上 GitHub 热榜 —— 开源编程语言、框架哪有这么可爱？
北京人形机器人创新中心发布全球首个纯电驱拟人奔跑的全尺寸人形机器人“天工”
LFOSSA 源来如此公开课 | 掌握云原生未来：CNCF 认证全面攻略与备考秘籍
国产云输入法——仅华为无云端数据上传安全问题
开源日报 | 工业开源项目OGG 1.0；姐姐，你要和我一起配置火狐吗；苹果AI遥遥落后？Fedora 40
开放签电子签章：停止新增，优化体验，前进更进（五一假期前工作）
周排行
Metasploit文件目录与入侵基本概念
跨域(CORS)请求问题[No 'Access-Control-Allow-Origin' header is present on the requested resource]常见解决方案
CodeIgniter 源码解读之 CodeIgniter.php（二）
SAS入门之（四）改变数据类型
初识元组
[数学建模]数学建模算法和模型（B站视频）（二）
Nginx 服务器源码安装配置流程
C#实现语音视频录制 【基于MCapture + MFile】
开发进度4
下载安装vue的方法网址
每日归档
更多
2024-04-28(0)
2024-04-27(56)
2024-04-26(39)
2024-04-25(22)
2024-04-24(36)
2024-04-23(26)
2024-04-22(39)
2024-04-21(0)
2024-04-20(6)
2024-04-19(5)

代码天地 © 2018 codetd.com

境外服务器   最新电视剧2022