20160406javaweb 之JDBC简单案例

Posted 2020-07-06 华裳绕指柔

前几天写的user注册登录注销案例，没有用到数据库，现在做出改动，使用数据库存储信息：

一、首先我们需要建立一个数据库：

如下图：

 

创建数据库的代码如下：

-- 导出 database02 的数据库结构
CREATE DATABASE IF NOT EXISTS `database02` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `database02`;


-- 导出  表 database02.users 结构
CREATE TABLE IF NOT EXISTS `users` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `username` varchar(20) NOT NULL,
  `password` varchar(50) NOT NULL,
  `nickname` varchar(40) NOT NULL,
  `email` varchar(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

二、创建包和类

1.创建一个接口

package com.dzq.dao;

import com.dzq.domian.User;

public interface UserDao {
   
    /**
     * 根据用户名查找用户
     * @param username 用户名
     * @return 根据用户名找到的用户信息，如果没找到，返回null
     */
    public User findUserByUserName(String username);
    
    /**
     * 添加用户
     * @param user 要添加用户信息的bean
     */
    public void addUser(User user);
    /**
     * 根据用户名密码查找用户信息
     * @param username 用户名
     * @param password 密码
     * @return 找到的用户，找不到返回null 
     */
    public User findUserByUNAndPWD(String username,String password);
}

2.创建操作数据库的工具类：

 

package com.dzq.util;

import java.io.FileReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JDBCUtils {
    
   private static  Properties prop=null;
   
   private JDBCUtils(){
    
   }
   
   /**
    * 静态代码块，加载数据库配置文件
    */
   static{
       try{
        prop=new Properties();
        prop.load(new FileReader(JDBCUtils.class.getClassLoader().getResource("config.properties").getPath()));
       }catch(Exception e){
           e.printStackTrace();
           throw new RuntimeException();
       }
   }
   
   /**
    * 获取连接
    */
   public static Connection getConn() throws Exception{
      
       
       Class.forName(prop.getProperty("driver"));
       return DriverManager.getConnection(prop.getProperty("url"), prop.getProperty("user"), prop.getProperty("password"));
   }
   
   /**
    * 关闭连接
    */
   public static void close(ResultSet rs,Statement stat,Connection conn){
       if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }finally{
                rs=null;
            }
        }
        if(stat!=null){
            try {
                stat.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }finally{
                stat=null;
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }finally{
                conn=null;
            }
        }
   }
}

 

3.创建异常处理类

package com.dzq.exception;

public class MsgException extends Exception {
public MsgException(){

}

public MsgException(String msg){
    super(msg);
}
}

 

4.创建javabean类

package com.dzq.domian;

import java.io.Serializable;

import com.dzq.exception.MsgException;

public class User implements Serializable{
    private int id;
private String username;
private String password;
private String password2;
private String nickname;
private String email;


public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getUsername() {
    return username;
}
public void setUsername(String username) {
    this.username = username;
}
public String getPassword() {
    return password;
}
public void setPassword(String password) {
    this.password = password;
}
public String getPassword2() {
    return password2;
}
public void setPassword2(String password2) {
    this.password2 = password2;
}
public String getNickname() {
    return nickname;
}
public void setNickname(String nickname) {
    this.nickname = nickname;
}
public String getEmail() {
    return email;
}
public void setEmail(String email) {
    this.email = email;
}

public User(){
    
}
public User(String username, String password, String password2,
        String nickname, String email) {
    
    this.username = username;
    this.password = password;
    this.password2 = password2;
    this.nickname = nickname;
    this.email = email;
}
@Override
public String toString() {
    return username+":"+password;
}
public void checkValue() throws MsgException{
    if(username==null||"".equals(username)){
        throw new MsgException("用户名不能为空");
    }
    if(password==null||"".equals(password)){
        throw new MsgException("密码不能为空");
    }
    if(password2==null||"".equals(password2)){
        throw new MsgException("密码不能为空");
    }
    if(!password.equals(password2)){
        throw new MsgException("两次密码输入不一致");
    }
    if(nickname==null||"".equals(nickname)){
        throw new MsgException("昵称不能为空");
    }
    if(email==null||"".equals(email)){
        throw new MsgException("邮箱不能为空");
    }
}

}

5.实现上述接口

package com.dzq.dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

import com.dzq.domian.User;
import com.dzq.util.JDBCUtils;

public class mysqlUserDao implements UserDao{
    
    @Override
    public User findUserByUserName(String username) {
        String sql="select * from users where username=\'"+username+"\'";
        Connection conn=null;
        Statement stat=null;
        ResultSet rs=null;
        try {
            conn=JDBCUtils.getConn();
            stat=conn.createStatement();
            rs=stat.executeQuery(sql);
            if(rs.next()){
                User user=new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("username"));
                user.setPassword(rs.getString("password"));
                user.setNickname(rs.getString("nickname"));
                user.setEmail(rs.getString("email"));
                return user;
            }else{
                return null;
            }
        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }finally{
            JDBCUtils.close(rs, stat, conn);
        }
    }

    @Override
    public void addUser(User user) {
    String sql="insert into users values (null,\'"+user.getUsername()+"\',\'"+user.getPassword()+"\',\'"+user.getNickname()+"\',\'"+user.getEmail()+"\')";
    Connection conn=null;
    Statement stat=null;
    ResultSet rs=null;
    try {
        conn=JDBCUtils.getConn();
        stat=conn.createStatement();
        int count=stat.executeUpdate(sql);
        
    } catch (Exception e) {
        e.printStackTrace();
        throw new RuntimeException(e);
    }finally{
        JDBCUtils.close(rs, stat, conn);
    }
    }

    @Override
    public User findUserByUNAndPWD(String username, String password) {
        String sql="select * from users where username=\'"+username+"\'and password=\'"+password+"\'";
        Connection conn=null;
        Statement stat=null;
        ResultSet rs=null;
        try {
            conn=JDBCUtils.getConn();
            stat=conn.createStatement();
            rs=stat.executeQuery(sql);
            if(rs.next()){
                User user=new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("username"));
                user.setPassword(rs.getString("password"));
                user.setNickname(rs.getString("nickname"));
                user.setEmail(rs.getString("email"));
                return user;
            }else{
                return null;
            }
        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }finally{
            JDBCUtils.close(rs, stat, conn);
        }
    }

}

6.创建service类

package com.dzq.service;

import com.dzq.dao.MySqlUserDao;
import com.dzq.dao.XmlUserDao;
import com.dzq.domian.User;
import com.dzq.exception.MsgException;

public class UserService {
    //private  XmlUserDao dao=new XmlUserDao();
    private MySqlUserDao dao=new MySqlUserDao();
    /**
     * 添加用户
     * @param user
     * @throws MsgException 
     */
    public void registUser(User user) throws MsgException{
        if(dao.findUserByUserName(user.getUsername())!=null){
            throw new MsgException("用户名已经存在");
        }
        dao.addUser(user);
    }
    /**
     * 检查用户名是否正确
     * @param username
     * @param password
     */
    public User isUser(String username,String password){
        return dao.findUserByUNAndPWD(username, password);
        
    }
}

7.建立几个servlet

package com.dzq.web;

import java.io.IOException;
import java.net.URLEncoder;

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

import com.dzq.domian.User;
import com.dzq.service.UserService;


@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
   
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        UserService service=new UserService();
        User user=service.isUser(username, password);
        if(user==null){
            request.setAttribute("msg", "用户名或者密码错误");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }else{
            request.getSession().setAttribute("user", user);
            if("ok".equals(request.getParameter("remname"))){
                Cookie remNameC=new Cookie("remname",URLEncoder.encode(user.getUsername(),"utf-8"));
                remNameC.setPath(request.getContextPath());
                remNameC.setMaxAge(3600*24*30);
                response.addCookie(remNameC);
            }else{
                Cookie remNameC=new Cookie("remname","");
                remNameC.setPath(request.getContextPath());
                remNameC.setMaxAge(0);
                response.addCookie(remNameC);
            }
            response.sendRedirect(request.getContextPath()+"/index.jsp");
        }
    }

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

}

package com.dzq.web;

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;


@WebServlet("/LogOutServlet")
public class LogOutServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        if(request.getSession(false)!=null&&request.getSession().getAttribute("user")!=null){
            request.getSession().invalidate();
            response.sendRedirect(request.getContextPath()+"/index.jsp");
        }
    }

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

}

package com.dzq.web;

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 org.apache.commons.beanutils.BeanUtils;

import com.dzq.domian.User;
import com.dzq.exception.MsgException;
import com.dzq.service.UserService;


@WebServlet("/RegistServlet")
public class RegistServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
   
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        try {
            UserService service=new UserService();
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        //1。检验验证码
        String valistr=request.getParameter("valistr");
        String valistr2=(String) request.getSession().getAttribute("valistr");
        if(valistr==null||valistr2==null||!valistr.equals(valistr2)){
            request.setAttribute("msg", "验证码不正确");
            request.getRequestDispatcher("/regist.jsp").forward(request, response);
            return;
        }
        //2.封装数据，校验数据
        User user=new User();
        BeanUtils.populate(user, request.getParameterMap());
        user.checkValue();
        service.registUser(user);
        request.getSession().setAttribute("user", user);
        response.getWriter().write("恭喜您注册成功，3秒回到主页");
        response.setHeader("refresh", "3;url="+request.getContextPath()+"/index.jsp");
        }catch(MsgException e){
            request.setAttribute("msg",e.getMessage());
            request.getRequestDispatcher("/regist.jsp").forward(request, response);
            return;
        }catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        } 
        //3.调用service方法添加用户
        
        //4.提示注册成功，3秒跳转主页
    }

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

}

package com.dzq.web;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

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


@WebServlet("/ValiImg")
public class ValiImg extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
   
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        response.setDateHeader("Expires", -1);
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma","no-cache");
        //1.在内存中构建一张图片
        int height=30;
        int width=120;
        int xpyl=5;
        int ypyl=22;
        int bang=20;
        BufferedImage img=new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
        //2.获取图像上的画布
        Graphics2D g=(Graphics2D) img.getGraphics();
        //3.设置背景色
        g.setColor(Color.LIGHT_GRAY);
        g.fillRect(0, 0, width, height);
        //4.设置边框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width-2, height-2);
        //5.画干扰线
        for(int i=0;i<5;i++){
        g.setColor(Color.RED);
        g.drawLine(randNum(0, width), randNum(0, height), randNum(0, width), randNum(0, height));
        }
        //6.写字
        String base = "\\u7684\\u4e00\\u4e86\\u662f\\u6211\\u4e0d\\u5728\\u4eba\\u4eec\\u6709\\u6765\\u4ed6\\u8fd9\\u4e0a\\u7740\\u4e2a\\u5730\\u5230\\u5927\\u91cc\\u8bf4\\u5c31\\u53bb\\u5b50\\u5f97\\u4e5f\\u548c\\u90a3\\u8981\\u4e0b\\u770b\\u5929\\u65f6\\u8fc7\\u51fa\\u5c0f\\u4e48\\u8d77\\u4f60\\u90fd\\u628a\\u597d\\u8fd8\\u591a\\u6ca1\\u4e3a\\u53c8\\u53ef\\u5bb6\\u5b66\\u53ea\\u4ee5\\u4e3b\\u4f1a\\u6837\\u5e74\\u60f3\\u751f\\u540c\\u8001\\u4e2d\\u5341\\u4ece\\u81ea\\u9762\\u524d\\u5934\\u9053\\u5b83\\u540e\\u7136\\u8d70\\u5f88\\u50cf\\u89c1\\u4e24\\u7528\\u5979\\u56fd\\u52a8\\u8fdb\\u6210\\u56de\\u4ec0\\u8fb9\\u4f5c\\u5bf9\\u5f00\\u800c\\u5df1\\u4e9b\\u73b0\\u5c71\\u6c11\\u5019\\u7ecf\\u53d1\\u5de5\\u5411\\u4e8b\\u547d\\u7ed9\\u957f\\u6c34\\u51e0\\u4e49\\u4e09\\u58f0\\u4e8e\\u9ad8\\u624b\\u77e5\\u7406\\u773c\\u5fd7\\u70b9\\u5fc3\\u6218\\u4e8c\\u95ee\\u4f46\\u8eab\\u65b9\\u5b9e\\u5403\\u505a\\u53eb\\u5f53\\u4f4f\\u542c\\u9769\\u6253\\u5462\\u771f\\u5168\\u624d\\u56db\\u5df2\\u6240\\u654c\\u4e4b\\u6700\\u5149\\u4ea7\\u60c5\\u8def\\u5206\\u603b\\u6761\\u767d\\u8bdd\\u4e1c\\u5e2d\\u6b21\\u4eb2\\u5982\\u88ab\\u82b1\\u53e3\\u653e\\u513f\\u5e38\\u6c14\\u4e94\\u7b2c\\u4f7f\\u5199\\u519b\\u5427\\u6587\\u8fd0\\u518d\\u679c\\u600e\\u5b9a\\u8bb8\\u5feb\\u660e\\u884c\\u56e0\\u522b\\u98de\\u5916\\u6811\\u7269\\u6d3b\\u90e8\\u95e8\\u65e0\\u5f80\\u8239\\u671b\\u65b0\\u5e26\\u961f\\u5148\\u529b\\u5b8c\\u5374\\u7ad9\\u4ee3\\u5458\\u673a\\u66f4\\u4e5d\\u60a8\\u6bcf\\u98ce\\u7ea7\\u8ddf\\u7b11\\u554a\\u5b69\\u4e07\\u5c11\\u76f4\\u610f\\u591c\\u6bd4\\u9636\\u8fde\\u8f66\\u91cd\\u4fbf\\u6597\\u9a6c\\u54ea\\u5316\\u592a\\u6307\\u53d8\\u793e\\u4f3c\\u58eb\\u8005\\u5e72\\u77f3\\u6ee1\\u65e5\\u51b3\\u767e\\u539f\\u62ff\\u7fa4\\u7a76\\u5404\\u516d\\u672c\\u601d\\u89e3\\u7acb\\u6cb3\\u6751\\u516b\\u96be\\u65e9\\u8bba\\u5417\\u6839\\u5171\\u8ba9\\u76f8\\u7814\\u4eca\\u5176\\u4e66\\u5750\\u63a5\\u5e94\\u5173\\u4fe1\\u89c9\\u6b65\\u53cd\\u5904\\u8bb0\\u5c06\\u5343\\u627e\\u4e89\\u9886\\u6216\\u5e08\\u7ed3\\u5757\\u8dd1\\u8c01\\u8349\\u8d8a\\u5b57\\u52a0\\u811a\\u7d27\\u7231\\u7b49\\u4e60\\u9635\\u6015\\u6708\\u9752\\u534a\\u706b\\u6cd5\\u9898\\u5efa\\u8d76\\u4f4d\\u5531\\u6d77\\u4e03\\u5973\\u4efb\\u4ef6\\u611f\\u51c6\\u5f20\\u56e2\\u5c4b\\u79bb\\u8272\\u8138\\u7247\\u79d1\\u5012\\u775b\\u5229\\u4e16\\u521a\\u4e14\\u7531\\u9001\\u5207\\u661f\\u5bfc\\u665a\\u8868\\u591f\\u6574\\u8ba4\\u54cd\\u96ea\\u6d41\\u672a\\u573a\\u8be5\\u5e76\\u5e95\\u6df1\\u523b\\u5e73\\u4f1f\\u5fd9\\u63d0\\u786e\\u8fd1\\u4eae\\u8f7b\\u8bb2\\u519c\\u53e4\\u9ed1\\u544a\\u754c\\u62c9\\u540d\\u5440\\u571f\\u6e05\\u9633\\u7167\\u529e\\u53f2\\u6539\\u5386\\u8f6c\\u753b\\u9020\\u5634\\u6b64\\u6cbb\\u5317\\u5fc5\\u670d\\u96e8\\u7a7f\\u5185\\u8bc6\\u9a8c\\u4f20\\u4e1a\\u83dc\\u722c\\u7761\\u5174\\u5f62\\u91cf\\u54b1\\u89c2\\u82e6\\u4f53\\u4f17\\u901a\\u51b2\\u5408\\u7834\\u53cb\\u5ea6\\u672f\\u996d\\u516c\\u65c1\\u623f\\u6781\\u5357\\u67aa\\u8bfb\\u6c99\\u5c81\\u7ebf\\u91ce\\u575a\\u7a7a\\u6536\\u7b97\\u81f3\\u653f\\u57ce\\u52b3\\u843d\\u94b1\\u7279\\u56f4\\u5f1f\\u80dc\\u6559\\u70ed\\u5c55\\u5305\\u6b4c\\u7c7b\\u6e10\\u5f3a\\u6570\\u4e61\\u547c\\u6027\\u97f3\\u7b54\\u54e5\\u9645\\u65e7\\u795e\\u5ea7\\u7ae0\\u5e2e\\u5566\\u53d7\\u7cfb\\u4ee4\\u8df3\\u975e\\u4f55\\u725b\\u53d6\\u5165\\u5cb8\\u6562\\u6389\\u5ffd\\u79cd\\u88c5\\u9876\\u6025\\u6797\\u505c\\u606f\\u53e5\\u533a\\u8863\\u822c\\u62a5\\u53f6\\u538b\\u6162\\u53d4\\u80cc\\u7ec6";
        StringBuffer buffer=new StringBuffer();
        
        for(int i=0;i<4;i++){
            g.setColor(new Color(randNum(0, 255),randNum(0, 255),randNum(0, 255)));
            g.setFont(new Font("黑体",Font.BOLD,bang));
            int r=randNum(-45, 45);
            g.rotate(1.0*r/180*Math.PI,xpyl+i*30, ypyl);
            String s=base.charAt(randNum(0, base.length()-1))+"";
            buffer.append(s);
            g.drawString(s, xpyl+i*30, ypyl);
            g.rotate(1.0*-r/180*Math.PI,xpyl+i*30, ypyl);
        }
        request.getSession().setAttribute("valistr", buffer.toString());
        System.out.println(buffer.toString());
        //将图片输出到浏览器
        ImageIO.write(img, "jpg", response.getOutputStream());
        
    }
    private Random rand=new Random();
    private int randNum(int begin,int end){
        
     return rand.nextInt((end-begin)+begin);        
        
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
    }
}

8. jsp页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
</head>
<body>
<h1>我的网站</h1><hr>
<c:if test="${sessionScope.user!=null}">
欢迎回来！${sessionScope.user.username }<a href="${pageContext.request.contextPath }/LogOutServlet">注销</a>
</c:if>

<c:if test="${sessionScope.user==null}">
游客，欢迎你！<a href="${pageContext.request.contextPath }/regist.jsp">注册</a>|<a href="${pageContext.request.contextPath }/login.jsp">登录</a>
</c:if>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"JavaWeb5.6JDBC：JDBC控制事务转账案例

 初学者学javaweb的学习内容有啥
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