SQL ----- JDBC 用ID查询某条记录

package demo;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Edit
 */
@WebServlet("/edit.do")
public class Edit extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public Edit() {
		super();
		// TODO Auto-generated constructor stub
	}

	/**
	 * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		//根据ID查询
		String id = request.getParameter("id");//获取参数--需要修改得记录的ID
		System.out.println(id);

		//设置数据库连接参数
		String url = "jdbc:mysql://localhost:3306/库名?serverTimezone=UTC";
		String user = "用户名";
		String password = "密码";

		//加载数据库驱动
		try {
			Class.forName("com.mysql.jdbc.Driver");// 加载数据库的JDBC驱动程序
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		
		Customer customer = new Customer();

		try (Connection connection = DriverManager.getConnection(url, user, password)) {//连接数据库

			//设置预处理语句,customers为表名
			String sql = "SELECT*FROM customers where customerID= ? ";
			PreparedStatement statement = connection.prepareStatement(sql);//预处理sql语句
			/*
			 * statement.setInt(1, Integer.parseInt(id));//Integer.parseInt(id)将字符串类型转换成整型
			 */
			int _id = Integer.parseInt(id);
			statement.setInt(1, _id);
			ResultSet rs = statement.executeQuery();

			while (rs.next()) {
				// 将数据库的数据转换成POJO实例
				customer.setCustomerID(rs.getInt("CustomerID"));
				customer.setCustomerName(rs.getString("CustomerName"));
				customer.setContactName(rs.getString("ContactName"));
				customer.setAddress(rs.getString("Address"));
				customer.setCity(rs.getString("City"));
				customer.setPostalCode(rs.getString("PostalCode"));
				customer.setCountry(rs.getString("Country"));

			} 
			
			rs.close();
			statement.close();
			
		} catch (SQLException e) {
			e.printStackTrace();
		}
		
		request.setAttribute("customer", customer);//将获取POJO实例传递到edit界面
		request.getRequestDispatcher("edit.jsp").forward(request, response);
	}

}