package com.fgy.jdbc; import java.sql.*; public class Demo1Jdbc { public static void main(String[] args) throws ClassNotFoundException, SQLException { // 1.导入驱动jar包 // 2.注册驱动 Class.forName("com.mysql.jdbc.Driver"); // 3.获取连接 Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1", "root", "root"); // 4.定义SQL语句 String sql = "select * from stu"; // 5.获取statement对象 Statement statement = con.createStatement(); // 6.执行SQL语句 ResultSet rs = statement.executeQuery(sql); // 7.处理结果 while (rs.next()) { System.out.println(rs.getString("name")); } // 8.释放资源 statement.close(); con.close(); } }
package com.fgy.jdbc; import java.sql.*; public class Demo2Jdbc { public static void main(String[] args) { Connection conn = null; PreparedStatement statement = null; try { // 1.导入驱动jar包 // 2.注册驱动 Class.forName("com.mysql.jdbc.Driver"); // 3.获取连接 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1", "root", "root"); // 4.定义SQL语句 String sql = "insert into stu(name) values ('筱筱')"; // 5.获取statement对象 statement = conn.prepareStatement(sql); // 6.执行SQL语句 // statement.execute(); int i = statement.executeUpdate(); System.out.println("受影响的行数:" + i); // 7.处理结果 // ... } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { // 8.释放资源 if (statement != null) { try { statement.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } }
package com.fgy.jdbc; import java.sql.*; import java.util.Scanner; /** * 登录小案例 */ public class login { public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println("请输入账号:"); String name = sc.next(); System.out.println("请输入密码:"); String password = sc.next(); boolean bool = login(name, password); if (bool) { System.out.println("登陆成功!"); } else { System.out.println("登录失败!"); } } private static boolean login(String name, String password) { if (name == null || password == null) { return false; } Connection conn = null; PreparedStatement pstm = null; ResultSet rs = null; try { // 1.导入驱动jar包 // 2.注册驱动 Class.forName("com.mysql.jdbc.Driver"); // 3.获取连接 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1", "root", "root"); // 4.定义SQL语句 // 为了防止SQL注入,不采用字符串拼接的方式,而是采用占位符的方式 String sql = "select * from user where name = ? and password = ?"; // 5.获取statement对象 pstm = conn.prepareStatement(sql); pstm.setString(1, name); // 给占位符赋值,参数位置从1开始 pstm.setString(2, password); // 6.执行SQL语句 rs = pstm.executeQuery(); // 7.处理结果 // 结果只有一条数据,移动游标时有数据返回true,没有数据返回false return rs.next(); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { // 8.释放资源 if (rs != null) { try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } } if (pstm != null) { try { pstm.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } return false; } }