import java.sql.Connection;import java.sql.DriverManager;public class DBUtil {    // 建立连接方法    public static Connection open() {        try {            Class.forName("com.mysql.jdbc.Driver");            return DriverManager.getConnection(                    "jdbc:mysql://localhost:3306/GeekDB", "root", "123456");        } catch (Exception e) {            e.printStackTrace();        }        return null;    }    // 关闭连接方法    public static void close(Connection conn) {        if (conn != null) {            try {                conn.close();            } catch (Exception e) {                e.printStackTrace();            }        }    }}

import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.Statement;public class Test {    public static void main(String[] args) {        Connection conn = null;        String sql = null;        Statement stmt = null;        PreparedStatement pstmt = null;        ResultSet rs = null;        // Statement查询*        sql = "select * from customertbl";        conn = DBUtil.open();        try {            stmt = conn.createStatement();            rs = stmt.executeQuery(sql);            while (rs.next()) {                int id = rs.getInt(1);                String name = rs.getString(2);                String email = rs.getString(3);                System.out.println(id + " " + name + " " + email);            }        } catch (Exception e) {            e.printStackTrace();        } finally {            DBUtil.close(conn);            System.out.println("-----DONE-----");        }        // PreparedStatement插入一条        sql = "insert into customertbl (name, email) values (?, ?)";        conn = DBUtil.open();        try {            pstmt = conn.prepareStatement(sql);            pstmt.setString(1, "Amy");            pstmt.setString(2, "amy@163.com");            pstmt.executeUpdate();        } catch (Exception e) {            e.printStackTrace();        } finally {            DBUtil.close(conn);            System.out.println("-----DONE-----");        }    }}