JDBC 增删查改(2)

1 // ==================== Program Description ========================== 2 // 程序名称：示例13-2: User.java 3 // 程序目的：创建一个用来操作用户信息的类 4 // ============================================================== 5 public class User 6 { 7 private String username; 8 private String password; 9 private String regDate; 10 11 // 获取用户名 12 public String getUsername() { 13 return username; 14 } 15 16 // 设置用户名 17 public void setUsername(String username) { 18 this.username = username; 19 } 20 21 // 获取用户密码 22 public String getPassword() { 23 return password; 24 } 25 26 // 设置用户密码 27 public void setPassword(String password) { 28 this.password = password; 29 } 30 31 // 获取用户注册时间 32 public String getRegDate() { 33 return regDate; 34 } 35 36 // 设置用户注册时间 37 public void setRegDate(String regDate) { 38 this.regDate = regDate; 39 } 40 } 

 

1 // ==================== Program Description ========================== 2 // 程序名称：示例13-3: UserMgr.java 3 // 程序目的：利用JDBC对数据库进行增删查改操作 4 // ============================================================== 5 import java.sql.*; 6 import test.DBConnection; 7 8 public class UserMgr 9 { 10 // 向数据库中添加用户信息 11 public boolean addUser(User user) 12 { 13 // 构造SQL语句 14 String sql = "insert into tbl_user (vcUsername, vcPassword,dtRegDate) values('" + 15 user.getUsername() + "','" + user.getPassword() +"',getDate())"; 16 Statement stmt; 17 Connection conn; 18 try { 19 // 获取数据库连接 20 conn = DBConnection.getConnection(); 21 22 // 创建Statement对象 23 stmt = conn.createStatement(); 24 25 // 执行SQL语句 26 stmt.executeUpdate(sql); 27 stmt.close(); 28 conn.close(); 29 30 return true; 31 } 32 catch (SQLException e) { 33 System.out.println(e.getMessage()); 34 } 35 36 return false; 37 } 38 39 // 删除数据库中某个用户的信息 40 public boolean deleteUser(User user) 41 { 42 String sql="delete from tbl_user where vcUsername="+"'"+user.getUsername()+"'"; 43 Connection conn; 44 Statement stmt; 45 46 try { 47 conn=DBConnection.getConnection(); 48 stmt=conn.createStatement(); 49 stmt.executeUpdate(sql); 50 stmt.close(); 51 conn.close(); 52 53 return true; 54 } 55 catch (SQLException e) 56 { 57 System.out.println(e.getMessage()); 58 } 59 60 return false; 61 } 62 63 // 根据用户名查询数据库获取一个用户对象 64 public User getUser( String username ) 65 { 66 User user; 67 String sql="select * from tbl_user where vcUsername='"+username+"'"; 68 Statement stmt; 69 Connection conn; 70 71 try { 72 conn= DBConnection.getConnection(); 73 stmt=conn.createStatement(); 74 75 // 执行SQL语句并将查询结果放入结果集中 76 ResultSet rs=stmt.executeQuery(sql); 77 78 // 将结果集中的数据取出放入User类的对象中 79 if (rs.next()) 80 { 81 user=new User(); 82 user.setUsername(rs.getString("vcUsername")); 83 user.setPassword(rs.getString("vcPassword")); 84 user.setRegDate(rs.getDate("dtRegDate").toString()); 85 stmt.close(); 86 conn.close(); 87 return user; 88 } 89 } 90 catch (SQLException e) 91 { 92 System.out.println(e.getMessage()); 93 } 94 95 return null; 96 } 97 98 // 通过验证密码鉴定用户的身份 99 public int checkUser(User user) 100 { 101 User dbUser= getUser(user.getUsername()); 102 if (dbUser==null) 103 return 0; 104 else if (dbUser.getPassword().equals(user.getPassword()) ) 105 return 1; 106 else return -1; 107 } 108 109 // 修改数据库中某个用户的信息 110 public boolean modifyUser(User user) 111 { 112 Connection conn; 113 Statement stmt; 114 String sql="update tbl_user set vcPassword= '"+user.getPassword()+"' where 115 vcUsername='"+user.getUsername()+"'"; 116 117 try { 118 conn=DBConnection.getConnection(); 119 stmt=conn.createStatement(); 120 stmt.executeUpdate(sql); 121 stmt.close(); 122 conn.close(); 123 124 return true; 125 } 126 catch (SQLException e) 127 { 128 System.out.println(e.getMessage()); 129 } 130 131 return false; 132 } 133 }