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JDBC MySQL 实例之 用户管理系统
1 Java 和 MySQL 怎么建立连接
2 通过Java怎么对数据库进行操作
1 package day01; 2 3 import java.sql.Connection; 4 import java.sql.DriverManager; 5 import java.sql.ResultSet; 6 import java.sql.SQLException; 7 import java.sql.Statement; 8 import java.util.ArrayList; 9 import java.util.List; 10 import java.util.Scanner; 11 12 /** 13 * 用户登录系统 14 * Description: 15 */ 16 public class Service { 17 private static final int USER_REG = 1; 18 private static final int USER_LOGIN = USER_REG + 1; 19 private static final int USER_UPDATE = USER_LOGIN + 1; 20 private static final int USER_DELETE = USER_UPDATE + 1; 21 private static final int USER_INFO = USER_DELETE + 1; 22 private static final int USER_TRANSFER = USER_INFO + 1; 23 private static final int USER_QUIT = USER_TRANSFER + 1; 24 private static final int EXIT = USER_QUIT + 1; 25 26 UserInfo user = null; 27 28 public static void main(String[] args) { 29 Service serv = new Service(); 30 serv.start(); 31 } 32 33 private void start() { 34 welcome(); 35 int code = getCode(); 36 execute(code); 37 } 38 39 /** 40 * 执行选择 41 * Description: 42 */ 43 private void execute(int code) { 44 switch (code) { 45 case USER_REG: 46 user_reg(); 47 break; 48 case USER_LOGIN: 49 user_login(); 50 break; 51 case USER_UPDATE: 52 user_update(); 53 break; 54 case USER_DELETE: 55 user_delete(); 56 break; 57 case USER_INFO: 58 user_info(); 59 break; 60 case USER_TRANSFER: 61 user_transfer(); 62 break; 63 case USER_QUIT: 64 user_quit(); 65 break; 66 case EXIT: 67 exit(); 68 break; 69 default: 70 System.out.println("输入错误，请重新输入"); 71 start(); 72 break; 73 } 74 } 75 76 /** 77 * Description: 78 */ 79 private void exit() { 80 // TODO Auto-generated method stub 81 if(null != this.user) { 82 System.out.println("当前用户还没有退出，所以执行自动退出当前用户"); 83 user_quit(); 84 }else { 85 System.out.println("你选择了退出系统"); 86 System.out.println("系统退出成功"); 87 } 88 89 } 90 91 /** 92 * 退出当前用户 93 * Description: 94 */ 95 private void user_quit() { 96 // TODO Auto-generated method stub 97 if(null != this.user) { 98 System.out.println("你选择了退出当前用户功能"); 99 this.user = null; 100 if(null == this.user) { 101 System.out.println("成功退出当前用户"); 102 }else { 103 System.out.println("退出当前用户失败"); 104 } 105 }else { 106 System.out.println("你还没有登录成功，还不能使用该功能"); 107 System.out.println("请登录！"); 108 user_login(); 109 } 110 start(); 111 } 112 113 /** 114 * 转账功能 115 * Description: 116 */ 117 private void user_transfer() { 118 // TODO Auto-generated method stub 119 if(null != this.user) { 120 System.out.println("你选择了转账功能！"); 121 Scanner scanner = new Scanner(System.in); 122 System.out.println("请输入转入账户的用户名："); 123 String name = scanner.nextLine(); 124 System.out.println("请输入转账金额："); 125 int money = Integer.parseInt(scanner.nextLine()); 126 127 Connection conn = null; 128 try { 129 Class.forName("com.mysql.jdbc.Driver"); 130 conn = DriverManager.getConnection( 131 "jdbc:mysql://localhost:3306/test", 132 "root", 133 "182838"); 134 Statement state = conn.createStatement(); 135 136 //转出 137 String out_sql = "UPDATE userinfo_fury " 138 + "SET account = account - ‘"+money+"‘ " 139 + "WHERE username = ‘"+this.user.getUsername()+"‘ "; 140 int judge01 = state.executeUpdate(out_sql); 141 if(judge01 > 0) { 142 System.out.println("转出成功"); 143 }else { 144 System.out.println("转出失败"); 145 } 146 147 //转入 148 String in_sql = "UPDATE userinfo_fury " 149 + "SET account = account + ‘"+money+"‘ " 150 + "WHERE username = ‘"+name+"‘ "; 151 int judge02 = state.executeUpdate(in_sql); 152 if(judge02 > 0) { 153 System.out.println("转入成功"); 154 }else { 155 System.out.println("转入失败"); 156 } 157 }catch(Exception e) { 158 e.printStackTrace(); 159 }finally { 160 if(null != conn) { 161 try { 162 conn.close(); 163 }catch(SQLException e1) { 164 e1.printStackTrace(); 165 } 166 } 167 } 168 }else { 169 System.out.println("请先登录！"); 170 user_login(); 171 } 172 start(); 173 } 174 175 /** 176 * 查询表中的所有数据 177 * Description: 178 */ 179 private void user_info() { 180 // TODO Auto-generated method stub 181 if(null != this.user) { 182 System.out.println("你选择了查询所有用户功能！"); 183 Connection conn = null; 184 try { 185 Class.forName("com.mysql.jdbc.Driver"); 186 conn = DriverManager.getConnection( 187 "jdbc:mysql://localhost:3306/test", 188 "root", 189 "182838"); 190 Statement state = conn.createStatement(); 191 String sql = "SELECT id,username,password,email,nickname,account " 192 + "FROM userinfo_fury "; 193 ResultSet rs = state.executeQuery(sql); 194 List<UserInfo> list = new ArrayList<UserInfo>(); 195 196 while(rs.next()) { 197 int id = rs.getInt("id"); 198 String username = rs.getString("username"); 199 String password = rs.getString("password"); 200 String email = rs.getString("email"); 201 String nickname = rs.getString("nickname"); 202 double account = rs.getDouble("account"); 203 UserInfo userinfo = new UserInfo(id, username, password, email, nickname, account); 204 list.add(userinfo); 205 } 206 for(UserInfo lis : list) { 207 System.out.println(lis); 208 } 209 }catch(Exception e) { 210 e.printStackTrace(); 211 }finally { 212 if(null != conn) { 213 try { 214 conn.close(); 215 }catch(SQLException e1) { 216 e1.printStackTrace(); 217 } 218 } 219 } 220 }else { 221 System.out.println("请先登录"); 222 user_login(); 223 } 224 start(); 225 } 226 227 /** 228 * 删除用户 229 * Description: 230 */ 231 private void user_delete() { 232 // TODO Auto-generated method stub 233 if(null != this.user) { 234 System.out.println("你选择了删除用户功能"); 235 System.out.println("你不是超级用户，你无法使用删除用户功能"); 236 }else { 237 System.out.println("请先登录！"); 238 user_login(); 239 } 240 start(); 241 } 242 243 /** 244 * 修改用户信息 245 * Description: 246 */ 247 private void user_update() { 248 // TODO Auto-generated method stub 249 if(null != this.user) { 250 System.out.println("你选择了修改当前用户功能!"); 251 //可改进 -->> 可由用户选择需要修改的字段 252 System.out.println("你当前的昵称为：" + this.user.getNickname()); 253 Scanner scanner = new Scanner(System.in); 254 System.out.println("你想将你的昵称修改为："); 255 String nickname = scanner.nextLine(); 256 257 Connection conn = null; 258 try { 259 Class.forName("com.mysql.jdbc.Driver"); 260 conn = DriverManager.getConnection( 261 "jdbc:mysql://localhost:3306/test", 262 "root", 263 "182838"); 264 Statement state = conn.createStatement(); 265 266 String sql = "UPDATE userinfo_fury " 267 + "SET nickname = ‘"+nickname+"‘ " 268 + "WHERE username = ‘"+this.user.getUsername()+"‘ "; 269 int judge = state.executeUpdate(sql); 270 if(judge > 0) { 271 this.user.setNickname(nickname); 272 System.out.println("修改昵称成功,当前昵称为：" + this.user.getNickname()); 273 }else { 274 System.out.println("修改昵称失败"); 275 } 276 }catch(Exception e) { 277 e.printStackTrace(); 278 }finally { 279 if(null != conn) { 280 try { 281 conn.close(); 282 }catch(SQLException e1) { 283 e1.printStackTrace(); 284 } 285 } 286 } 287 }else { 288 System.out.println("请登录成功后在进行此操作！"); 289 user_login(); 290 } 291 start(); 292 } 293 294 /** 295 * 用户登录 296 * Description: 297 */ 298 private void user_login() { 299 // TODO Auto-generated method stub 300 System.out.println("你选择了用户登录功能！"); 301 Scanner scanner = new Scanner(System.in); 302 System.out.println("请输入用户名:"); 303 String username = scanner.nextLine(); 304 System.out.println("请输入密码："); 305 String password = scanner.nextLine(); 306 307 Connection conn = null; 308 try { 309 Class.forName("com.mysql.jdbc.Driver"); 310 conn = DriverManager.getConnection( 311 "jdbc:mysql://localhost:3306/test", 312 "root", 313 "182838"); 314 Statement state = conn.createStatement(); 315 316 String sql = "SELECT id, username, password,email, nickname,account " 317 + "FROM userinfo_fury " 318 + "WHERE username = ‘"+username+"‘ " 319 + "AND password = ‘"+password+"‘ "; 320 System.out.println(sql); 321 ResultSet rs = state.executeQuery(sql); 322 if(rs.next()) { 323 int id = rs.getInt("id"); 324 String name = rs.getString("username"); 325 String word = rs.getString("password"); 326 String email = rs.getString("email"); 327 String nickname = rs.getString("nickname"); 328 double account = rs.getDouble("account"); 329 UserInfo userinfo = new UserInfo(id, name, word, email, nickname, account); 330 this.user = userinfo; 331 System.out.println("登录成功,你的昵称为：" + this.user.getNickname()); 332 }else { 333 System.out.println("登录失败:" + this.user); 334 } 335 /* 336 * 注意： 337 * 当用户输入的密码个的格式是： 任意字符‘ or ‘数值开头 时无论用户名和密码正确与否，都会登录成功 338 * 因为 如果这样输入就改变了 SQL 语句的原意（在SQL语句中AND的优先级要高于OR） 339 * 实例 ： asdfaer1234‘ or ‘1 340 */ 341 }catch(Exception e) { 342 e.printStackTrace(); 343 }finally { 344 if(null != conn) { 345 try { 346 conn.close(); 347 }catch(SQLException e1) { 348 e1.printStackTrace(); 349 } 350 } 351 } 352 start(); 353 } 354 355 /** 356 * 用户注册 357 * Description: 358 */ 359 private void user_reg() { 360 System.out.println("你选择了用户注册功能！"); 361 Scanner scanner = new Scanner(System.in); 362 System.out.println("请输入用户名："); 363 String username = scanner.nextLine(); 364 System.out.println("请输入密码："); 365 String password = scanner.nextLine(); 366 System.out.println("请输入邮箱："); 367 String email = scanner.nextLine(); 368 System.out.println("请输入昵称："); 369 String nickname = scanner.nextLine(); 370 Connection conn = null; 371 try { 372 Class.forName("com.mysql.jdbc.Driver"); 373 conn = DriverManager.getConnection( 374 "jdbc:mysql://localhost:3306/test", 375 "root", 376 "182838"); 377 Statement state = conn.createStatement(); 378 String sql = "INSERT INTO userinfo_fury " 379 + "(username,password,email,nickname) " 380 + "VALUES " 381 + "(‘"+username+"‘,‘"+password+"‘,‘"+email+"‘,‘"+nickname+"‘)"; 382 int judge = state.executeUpdate(sql); 383 if(judge > 0) { 384 System.out.println("注册成功"); 385 }else { 386 System.out.println("注册失败"); 387 } 388 }catch(Exception e) { 389 e.printStackTrace(); 390 }finally { 391 if(null != conn) { 392 try { 393 conn.close(); 394 }catch(SQLException e1) { 395 e1.printStackTrace(); 396 } 397 } 398 } 399 start(); 400 } 401 402 /** 403 * 功能选择 404 * Description: 405 */ 406 private int getCode() { 407 System.out.println("请选择功能："); 408 Scanner scanner = new Scanner(System.in); 409 int code = Integer.parseInt(scanner.nextLine()); 410 return code; 411 } 412 413 /** 414 * 界面信息 415 * Description: 416 */ 417 private void welcome() { 418 System.out.println("欢迎使用用户登录系统！"); 419 System.out.println("请输入需要操作的功能序号"); 420 System.out.println("======================"); 421 System.out.println("================"); 422 System.out.println("1 : 用户注册"); 423 System.out.println("2 : 用户登录"); 424 System.out.println("3 : 修改用户信息"); 425 System.out.println("4 : 删除用户"); 426 System.out.println("5 : 查看所有用户信息"); 427 System.out.println("6 : 转账业务"); 428 System.out.println("7 : 用户退出"); 429 System.out.println("8 : 退出系统"); 430 System.out.println("================"); 431 System.out.println("======================"); 432 } 433 }
上面程序用到的类
3 改进
改程序是典型的 高耦合、低内聚， 改进之处很多很多...
三少今天有点懒，笔记待更新...
2017年4月5日19:42:31
JDBC MySQL 实例之 用户管理系统
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