数据库的连接

连接数据库。
首先开启Tomcat数据库，利用eclipse创建一个web文本。
建立dao层servlet层util层。分别写入相应代码。用网站语言搭建网页jsp。在数据库里建立相应表，取不同名字注意与eclipse中对应属性的一一对应。首id主键递增非null。
<!-- 输入字段验证部分 -->
<script type="text/javascript">
function check(){
    var username=document.getElementById("gs1");
    var password=document.getElementById("gs2");
    var number=document.getElementById("gs5");
    var mail=document.getElementById("gs6");
    var sReg = /[_a-zA-Z\d\-\.]+@[_a-zA-Z\d\-]+(\.[_a-zA-Z\d\-]+)+$/; //正则表达式
    //判断用户名位数
    if((username.value).length<6||(username.value).length>12){
        alert('账号请输入6到12位英文字符或数字，以英文字母开头');
        gs1.focus();
        return false;
    }
    //判断用户名是否包含汉字
    if(/.*[\u4e00-\u9fa5]+.*$/.test(username.value)){
        alert('账号用户名不能包含汉字');
        gs1.focus();
        return false;
    }
    //判断用户名是否以英文字母开头
    if(!isNaN(username.value[0])){
        alert('登录账号请以英文字母开头');
        gs1.focus();
        return false;
    }
    //判断密码位数
    if((password.value).length!=8){
        alert('密码应为8位英文或数字');
        gs2.focus();
        return false;
    }
    //判断学号是否以2018开头
     if(number.value<"20180000"|| number.value>"20189999")
                {
                 alert(" 学号由2018开头的八位组成");             
                 gs5.focus();
                 return false;
                }
 
    //验证手机号是否合法
     
    //判断邮箱格式是否正确
    if(! sReg.test(mail.value)){   
        alert('邮箱格式错误');
        gs6.focus();
        return false;
    }  
}
</script>
<!-- 验证结束 -->
</body>
</html>

 这里面用JavaScript写了邮箱，账号等等的格式判断
添加成功界面如下:
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1 style="text-align:center;">添加成功</h1>
<h1 style="text-align:center;"><a href="text.jsp">返回继续添加信息</a></h1>
</body>
</html>
 添加失败界面如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1 style="text-align:center;">添加失败</h1>
<h1 style="text-align:center;"><a href="text.jsp">返回继续添加信息</a></h1>
</body>
</html>
 接下来开始封装数据和数据库建立连接，首先创建一个Bean包，来封装数据用代码如下:
package text.jsp.bean;
public class UserBean {
    private String id;
    private String password;
    private String sex;
    private String name;
    private String number;
    private String mail;
    private String yuan;
    private String xi;
    private String classes;
    private String time;
    private String place;
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getNumber() {
        return number;
    }
    public void setNumber(String number) {
        this.number = number;
    }
    public String getMail() {
        return mail;
    }
    public void setMail(String mail) {
        this.mail = mail;
    }
    public String getYuan() {
        return yuan;
    }
    public void setYuan(String yuan) {
        this.yuan = yuan;
    }
    public String getXi() {
        return xi;
    }
    public void setXi(String xi) {
        this.xi = xi;
    }
    public String getClasses() {
        return classes;
    }
    public void setClasses(String classes) {
        this.classes = classes;
    }
    public String getTime() {
        return time;
    }
    public void setTime(String time) {
        this.time = time;
    }
    public String getPlace() {
        return place;
    }
    public void setPlace(String place) {
        this.place = place;
    }
    public UserBean(String id,String password,String sex,String name,String number,String mail,String yuan,String xi,String classes,String time,String place){
        this.id=id;
        this.password=password;
        this.sex=sex;
        this.name=name;
        this.number=number;
        this.mail=mail;
        this.yuan=yuan;
        this.xi=xi;
        this.classes=classes;
        this.time=time;
        this.place=place;
    }
}
 然后创建一个util包主要是连接数据库以及判断数据库是否连接成功，若不成功则在控制台输出报错信息，这个代码一般都是直接复制的 只需要改一下数据库的名字。代码如下:
package text.jsp.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
public class DBUtil
{  
    private static Connection con;
    private static Statement stm;
    private static ResultSet rs;
    private static String classname="com.mysql.cj.jdbc.Driver";
    private static String url="jdbc:mysql://localhost:3306/gs?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT&&useSSL=false&&allowPublicKeyRetrieval=true";
    public  Connection getCon(){         
        try{
            Class.forName(classname);
            System.out.println("驱动加载成功");
        }
        catch(ClassNotFoundException e){
            e.printStackTrace();
        }
        try{
            con=DriverManager.getConnection(url,"root","123456");
            System.out.println("数据库连接成功");
             
        }
        catch(Exception e){
            e.printStackTrace(System.err);
            con=null;
        }
        return con;
    }
    public static void close(Statement stm, Connection conn) {
        if(stm!=null) {
            try {
                stm.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
     
    public static void close(ResultSet rs, Statement stm, Connection con) {
        if(rs!=null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(stm!=null) {
            try {
                stm.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(con!=null) {
            try {
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}
 Dao层这个主要是将数据传到数据库的相应位置，写代码的时候一定要变量一一对应，否则会报错。代码如下:
package text.jsp.dao;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import text.jsp.bean.UserBean;
import text.jsp.util.DBUtil;
 
public class UserDao {
    public boolean add(UserBean user) {
        String sql = "insert into text1021(id,password,sex,name,number,mail,yuan,xi,classes,time,place) values('" + user.getId() + "','" + user.getPassword() + "','" + user.getSex()  + "','" + user.getName()  + "','" + user.getNumber()  + "','" + user.getMail() + "','" + user.getYuan() +"','"+user.getXi() + "','" +user.getClasses() + "','" +user.getTime() + "','" + user.getPlace()+"')";
        DBUtil  db=new DBUtil();
        Connection conn =  db.getCon();//   ÷          
        Statement state = null;
        boolean f = false;
        int a = 0 ;
         
        try {        
            state = conn.createStatement();
            a = state.executeUpdate(sql);
        } catch (Exception e) {          
            e.printStackTrace();
        } finally {
                     
            DBUtil.close(state, conn);
        }
         
        if (a > 0) {
            f = true;
        }
        return f;
    }      
     
}
 servlet包，这个主要作用就是从jsp里面接受请求并作出判断并返回成功或者失败界面
代码如下：
package text.jsp.servlet;
import java.io.IOException;
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 text.jsp.dao.UserDao;
import text.jsp.bean.UserBean;
 
/**
 * Servlet implementation class textservlet
 */
@WebServlet("/textservlet")
public class textservlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
        
    /**
     * @see HttpServlet#HttpServlet()
     */
    public textservlet() {
        super();
        // TODO Auto-generated constructor stub
    }
    UserDao userDao=new UserDao();
    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        response.setContentType("textml;charset=UTF-8");
        response.setHeader("content-type", "textml;charset=UTF-8");
         String id=request.getParameter("gs1");
         String password=request.getParameter("gs2");
         String sex=request.getParameter("p");
         String name=request.getParameter("gs4");
         String number=request.getParameter("gs5");
         String mail=request.getParameter("gs6");
         String yuan=request.getParameter("gs7");
         String xi=request.getParameter("gs8");
         String classes=request.getParameter("gs9");
         String time=request.getParameter("p2");
         String place=request.getParameter("gs11");
         UserBean userbean=new UserBean( id, password, sex, name, number, mail, yuan, xi, classes, time, place);
         if(userDao.add(userbean)) {
                request.getRequestDispatcher("success.jsp").forward(request,response);
            }
            else {
                request.getRequestDispatcher("fail.jsp").forward(request,response);
            }
    }
 
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }
 
}