一
首先需要链接数据库的jar包 mysql-connector-java-5.0.4-bin.jar
二
用到的工具类
验证码图片的工具类 package com.yinhe.util; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.OutputStream; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class CodeServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String codes="abcdefghijklmnopqrstuvwxyz"; BufferedImage img=new BufferedImage(80,30,BufferedImage.TYPE_3BYTE_BGR); Graphics g=img.getGraphics(); //填充图片 g.setColor(new Color(255,255,255)); g.fillRect(0, 0, 80, 30); //画入五个随机数 Random rm=new Random(); StringBuffer sb=new StringBuffer(); for(int i=0;i<5;i++){ int index=rm.nextInt(codes.length()); char code=codes.charAt(index); g.setColor(new Color(rm.nextInt(256),rm.nextInt(256),rm.nextInt(256))); g.setFont(new Font("宋体", Font.BOLD, 25)); g.drawString(code+"", 2+15*i, 22); sb.append(code); } //画干扰线 for(int i=0;i<10;i++){ g.setColor(new Color(rm.nextInt(256),rm.nextInt(256),rm.nextInt(256))); g.drawLine(rm.nextInt(100), rm.nextInt(50), rm.nextInt(100), rm.nextInt(50)); } //将验证码图片回写给浏览器 response.setContentType("image/jpeg;charset=utf-8"); OutputStream out=response.getOutputStream(); ImageIO.write(img, "jpeg", out); //将随机字符串保存在session中 request.getSession().setAttribute("code", sb.toString()); } } 链接数据库的工具类 package com.yinhe.util; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class DbOperation { protected Connection conn; protected PreparedStatement ps; protected ResultSet rs; private final String uname="root"; private final String psw="root"; //获取数据库链接 public void getConn(){ try { //加载驱动 Class.forName("com.mysql.jdbc.Driver"); //获取链接 conn = DriverManager.getConnection( "jdbc:mysql:///test",uname,psw); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } //关闭 public void closeAll(){ try { if(conn!=null){ conn.close(); } if(ps!=null){ ps.close(); } if(rs!=null){ rs.close(); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } //更新 Object... 会把传过来的任意个object类型的变量封装成一个数组 public void extUpdate(String sql, Object... obj){ try { ps=conn.prepareStatement(sql); for(int i=0;i<obj.length;i++){ ps.setObject(i+1, obj[i]); } ps.executeUpdate(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } //查询 public void extQuery(String sql, Object... obj){ try { ps=conn.prepareStatement(sql); for(int i=0;i<obj.length;i++){ ps.setObject(i+1, obj[i]); } rs=ps.executeQuery(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } 封装类User package com.yinhe.vo; public class User { private int uid; private String username; private String psw; public int getUid() { return uid; } public void setUid(int uid) { this.uid = uid; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPsw() { return psw; } public void setPsw(String psw) { this.psw = psw; } public User(String username, String psw) { super(); this.username = username; this.psw = psw; } }
前台需要的登录页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <body> <form action="login" method="post"> username:<input name="username" type="text"> <br>password:<input name="psw" type="text"> <br>yanzhengma:<input name="yzm" type="text"> <img src="checkCode" alt="" id="codeImg" style="width: 80px; height: 30px; border: 1px solid black;" /> <a href="javascript:;" οnclick="document.getElementById('codeImg').src = 'checkCode?'+(new Date()).getTime()">换一张</a> <span id="codemsg" style="color: red; font-size: 20px;">${message}</span> <br><input type="submit" value="submit"> </form> </body> </html> controller层 package com.yinhe.controller; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.yinhe.service.LoginService; import com.yinhe.service.serviceImpl.LoginServiceImpl; import com.yinhe.vo.User; public class LoginServlet extends HttpServlet { private LoginService ls = new LoginServiceImpl(); @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub //获取前台参数 String username=req.getParameter("username"); String psw = req.getParameter("psw"); String yzm = req.getParameter("yzm"); // String yzmb = (String) req.getSession().getAttribute("code"); if (yzm.equals(yzmb)){ User user = new User(username,psw); String count = ls.doLogin(user); if (count.equals("0")){ req.setAttribute("message", "账户或密码错误"); req.getRequestDispatcher("/login.jsp").forward(req, resp); } else if (count.equals("1")){ req.getSession().setAttribute("username", user.getUsername()); req.getRequestDispatcher("/main.jsp").forward(req, resp); } } else{ req.setAttribute("message", "验证码错误"); req.getRequestDispatcher("/login.jsp").forward(req, resp); } } } Dao层接口 package com.yinhe.dao; import com.yinhe.vo.User; public interface LoginDao { public String doLogin(User user); } Dao代码 package com.yinhe.dao.daoImpl; import java.sql.SQLException; import com.yinhe.dao.LoginDao; import com.yinhe.util.DbOperation; import com.yinhe.vo.User; public class LoginDaoImpl extends DbOperation implements LoginDao { @Override public String doLogin(User user) { getConn(); String sql = "select count(*) from user where username=? and psw=?"; extQuery(sql, user.getUsername(),user.getPsw()); int count = 0; try { if(rs.next()){ count = rs.getInt(1); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } closeAll(); return count + ""; } } Service层接口
package com.yinhe.service; import com.yinhe.vo.User; public interface LoginService { public String doLogin(User user); }
Service层代码
package com.yinhe.service.serviceImpl; import com.yinhe.dao.LoginDao; import com.yinhe.dao.daoImpl.LoginDaoImpl; import com.yinhe.service.LoginService; import com.yinhe.vo.User; public class LoginServiceImpl implements LoginService { private LoginDao ld = new LoginDaoImpl(); @Override public String doLogin(User user) { return ld.doLogin(user); } }
