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 stub119 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 stub181 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 list = new ArrayList ();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 stub233 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 stub249 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 stub300 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 '1340 */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