Eclipse对mysql数据库进行增删改查

package com.hznu.qjc.daos; import com.hznu.qjc.users.*; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class DAO { private static Connection getConn() { Connection conn = null; try { Class.forName("com.mysql.jdbc.Driver"); //classLoader,加载对应驱动       } catch (ClassNotFoundException e) { e.printStackTrace(); } String url = "jdbc:mysql://localhost:3306/mysql?serverTimezone=UTC"; String username = "root";//数据库账户，一般为root String password = "liuhao";//数据库密码 try{ conn = DriverManager.getConnection(url, username, password); } catch (SQLException e) { e.printStackTrace(); } return conn; } public static int insert(Student student) { Connection conn = getConn(); int i = 0; String sql = "insert into students (Name,Sex,Age) values(?,?,?)"; PreparedStatement pstmt; try { pstmt = (PreparedStatement) conn.prepareStatement(sql); pstmt.setString(1, student.getName()); pstmt.setString(2, student.getSex()); pstmt.setString(3, student.getAge()); i = pstmt.executeUpdate(); pstmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } return i; } public static int update(Student student) { Connection conn = getConn(); int i = 0; String sql = "update students set Age='" + student.getAge() + "' where Name='" + student.getName() + "'"; PreparedStatement pstmt; try { pstmt = (PreparedStatement) conn.prepareStatement(sql); i = pstmt.executeUpdate(); System.out.println("resutl: " + i); pstmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } return i; } public static Integer getAll() { Connection conn = getConn(); String sql = "select * from students"; PreparedStatement pstmt; try { pstmt = (PreparedStatement)conn.prepareStatement(sql); ResultSet rs = pstmt.executeQuery(); int col = rs.getMetaData().getColumnCount(); System.out.println("============================"); while (rs.next()) { for (int i = 1; i <= col; i++) { System.out.print(rs.getString(i) + "\t"); if ((i == 2) && (rs.getString(i).length() < 8)) { System.out.print("\t"); } } System.out.println(""); } System.out.println("============================"); } catch (SQLException e) { e.printStackTrace(); } return null; } public static int delete(String name) { Connection conn = getConn(); int i = 0; String sql = "delete from students where Name='" + name + "'"; PreparedStatement pstmt; try { pstmt = (PreparedStatement) conn.prepareStatement(sql); i = pstmt.executeUpdate(); System.out.println("resutl: " + i); pstmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } return i; } }