SQL -------- JDBC 查询所有记录

package demo;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
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 Queryalldata
 */
@WebServlet("/queryalldata.jsp")
public class Queryalldata extends HttpServlet {
	private static final long serialVersionUID = 1L;

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

	/**
	 * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//查询所有数据

		//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();
		}

		List<Customer> list = new ArrayList<Customer>();//初始化一个Customer线性列表

		try(Connection connection=DriverManager.getConnection(url, user, password)){//连接数据库
			Statement statement = connection.createStatement();
			String sql="SELECT*FROM customers";//查询所有数据的sql语句,customers为表名
			ResultSet rs=statement.executeQuery(sql);

			//遍历数据库所有数据,并添加到列表list中
			while(rs.next()) {
				Customer customer = new Customer();
				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"));
				list.add(customer);
			}

			rs.close();
			statement.close();

		}catch(SQLException e) {
			e.printStackTrace();
		}

		String msg =(String) request.getAttribute("msg");
		if(msg!=null || msg !=" ")
			request.setAttribute("msg", msg);

		//将有数据的列表传递到显示记录所有界面
		request.setAttribute("customers", list);
		request.getRequestDispatcher("all.jsp").forward(request, response);
	}

}