public static Connection getConnection() throws IOException, ClassNotFoundException, SQLException {
        // 1、读取配置文件中的4个基本信息
        InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("jdbc.properties");
        Properties pros = new Properties();
        pros.load(is);

        String user = pros.getProperty("user");
        String password = pros.getProperty("password");
        String url = pros.getProperty("url");
        String driverClass = pros.getProperty("driverClass");

        // 2、加载驱动
        Class.forName(driverClass);

        // 3、获取连接
        Connection conn = DriverManager.getConnection(url, user, password);
        return conn;
    }

public static void closeResource(Connection conn, PreparedStatement ps) {
        try {
            if (ps != null)
                ps.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

package com.JDBCStudy3.PreparedStatement.crud;

import java.sql.Connection;
import java.sql.PreparedStatement;

import JDBC_util.JDBCutils;

public class PreparedStatementUpdateTest {

    // 修改customers表的一条数据
    public void testUpdate() {
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            // 1、获取数据库的连接
            conn = JDBCutils.getConnection();
            
            // 2、预编译sql语句，返回PreparedStatement的实例
            String sql = "update customers set name = ? where id = ?";
            conn.createStatement();
            ps = conn.prepareStatement(sql);

            // 3、填充占位符
            ps.setObject(1, "莫扎特");
            ps.setObject(2, 18);

            // 4、执行
            ps.execute();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            // 5、资源的关闭
            JDBCutils.closeResource(conn, ps);
        }
    }
}