javaweb使用jdbc获取MySQL数据

目录

 代码

User

package com.entity;

public class User {
    private int id;
    private String name;
    private String cityAreaName;
    private String address;
    private String phone;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCityAreaName() {
        return cityAreaName;
    }

    public void setCityAreaName(String cityAreaName) {
        this.cityAreaName = cityAreaName;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", cityAreaName='" + cityAreaName + '\'' +
                ", address='" + address + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }


    public User(int id, String name, String cityAreaName, String address,String phone) {
        super();
        this.id = id;
        this.name = name;
        this.cityAreaName = cityAreaName;
        this.address = address;
        this.phone = phone;
    }

    public User() {
        super();
    }
}

　　ServletDemo

ps：

这个不要直接复制，自己生成Servlet文件避免无用

生成Servlet文件：选择Servlet文件夹，右键new，选择Servlet

package com.servlet;

import com.entity.User;
import com.utils.DBHelper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

@WebServlet("/ServletDemo")//注意格式修改成这样，不要用默认的格式会报错
public class ServletDemo extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ServletDemo() {
        super();
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Connection conn = DBHelper.getConnection();
        String sql="select * from driveschool";
        try {
            Statement st = conn.createStatement();
            ResultSet rs = st.executeQuery(sql);
            User user = new User();
            while(rs.next()) {
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setCityAreaName(rs.getString("CityAreaName"));
                user.setAddress(rs.getString("address"));
                user.setPhone(rs.getString("Phone"));
            }
            //将数据库中查询到的信息封装在user对象中，use对象保存在request中，之后将通过request对象将数据传递到页面
            //需要的话也可以只传递一个参数request.setAttribute("id", user.getId());
            request.setAttribute("user", user);
            //这里是转发，从Servlet跳转到showinfo.jsp页面，并且带上request和response对象中原有的参数
            request.getRequestDispatcher("showinfo.jsp").forward(request, response);

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

　　DBHelper

package com.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBHelper {
    private static final String driver = "com.mysql.jdbc.Driver";
    private static final String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8";
    private static final String username = "root";
    private static final String password = "root";

    private static Connection conn=null;

    static {
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() {
        if(conn==null) {
            try {
                conn = DriverManager.getConnection(url,username,password);
                System.out.println("数据库初始化成功");
            } catch (SQLException e) {
                e.printStackTrace();
                System.out.println("数据库初始化失败");
            }
            return conn;
        }else {
            return conn;
        }
    }
}

　　数据库格式

 依赖包附件下载地址

https://dev.mysql.com/downloads/connector/j/

源码下载地址

 https://download.csdn.net/download/qq_41803637/11985600

怎么导入依赖包的地址

https://www.cnblogs.com/hahayixiao/p/10030491.html