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今天就跟大家聊聊有關Java web如何實現一個驗證碼權限登錄功能，可能很多人都不太了解，為了讓大家更加了解，小編給大家總結了以下內容，希望大家根據這篇文章可以有所收獲。
所用到的開發工具為myeclipse10，MySQL數據庫。
首先，在myeclipse中新建一個Java web項目。
項目的結構：
數據庫結構：
下面將各個包中的代碼粘貼出來。
com.ningmeng.dao包
package com.ningmeng.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.ningmeng.model.User;
public class UserDao {
public User login(Connection con,User user) throws SQLException{
User resultUser=null;
String sql="select * from user where username=? and password=?";
PreparedStatement ps=con.prepareStatement(sql);//
ps.setString(1, user.getUsername());
ps.setString(2, user.getPassword());
ResultSet rs=ps.executeQuery();
if(rs.next()){
resultUser=new User();
resultUser.setUsername(rs.getString("username"));
resultUser.setPassword(rs.getString("password"));
}
return resultUser;
}
}com.ningmeng.model包
package com.ningmeng.model;
public class User {
private int id;
private String username;
private String password;
public User() {
super();
}
public User(String username, String password) {
super();
this.username = username;
this.password = password;
}
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;
}
}com.ningmeng.util包
package com.ningmeng.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DbUtil {
private String url="jdbc:mysql://localhost:3306/db-jsp";
private String user="root";
private String password="123";
private String driver="com.mysql.jdbc.Driver";
public Connection getCon() throws Exception{
Class.forName(driver);
Connection con=DriverManager.getConnection(url, user, password);
return con;
}
public static void getClose(Connection con) throws SQLException{
if(con!=null){
con.close();
}
}
/*public static void main(String[] args) {
DbUtil db=new DbUtil();
try {
db.getCon();
System.out.println("測試連接數據庫，連接成功");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("測試連接數據庫，連接失敗");
}
}*/
}com.ningmeng.web包
package com.ningmeng.web;
import java.io.IOException;
import java.sql.Connection;
import java.io.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.http.*;
import com.ningmeng.dao.UserDao;
import com.ningmeng.model.User;
import com.ningmeng.util.DbUtil;
public class LoginServlet extends HttpServlet{
DbUtil db=new DbUtil();
UserDao userDao=new UserDao();
/**
*
*/
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username=request.getParameter("username");
String password=request.getParameter("password");
String checkcode=request.getParameter("checkCode");
HttpSession session=request.getSession();
//session.getAttribute("randCheckCode");
String s = (String)session.getAttribute("randCheckCode");
if(!checkcode.equals(s))
{
response.sendRedirect("linmao.jsp");
}else{
if(request.getParameter("ra").equals("l")){
Connection con=null;
try {
User user=new User(username,password);
con=db.getCon();
User currentUser=userDao.login(con, user);
if(currentUser==null){
//System.out.println("no");
request.setAttribute("error", "用戶名或者密碼錯誤");
request.setAttribute("username", username);
request.setAttribute("password", password);
request.getRequestDispatcher("login.jsp").forward(request, response);
}else{
//System.out.println("yes");
HttpSession session1=request.getSession();
session1.setAttribute("currentUser",currentUser);
response.sendRedirect("main.jsp");
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else{
response.sendRedirect("linmao.jsp");
}
}
}
}com.servlet包
package com.servlet;
import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.imageio.ImageIO;
public class PictureCheckCode extends HttpServlet {
private static final long serialVersionUID = 1L;
public PictureCheckCode() {
super();
}
public void destroy() {
super.destroy();
}
public void init() throws ServletException {
super.init();
}
/*該方法主要作用是獲得隨機生成的顏色*/
public Color getRandColor(int s,int e){
Random random=new Random ();
if(s>255) s=255;
if(e>255) e=255;
int r,g,b;
r=s+random.nextInt(e-s); //隨機生成RGB顏色中的r值
g=s+random.nextInt(e-s); //隨機生成RGB顏色中的g值
b=s+random.nextInt(e-s); //隨機生成RGB顏色中的b值
return new Color(r,g,b);
}
@Override
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//設置不緩存圖片
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "No-cache");
response.setDateHeader("Expires", 0);
//指定生成的響應圖片,一定不能缺少這句話,否則錯誤.
response.setContentType("image/jpeg");
int width=86,height=33; //指定生成驗證碼的寬度和高度
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //創建BufferedImage對象,其作用相當于一圖片
Graphics g=image.getGraphics(); //創建Graphics對象,其作用相當于畫筆
Graphics2D g2d=(Graphics2D)g; //創建Grapchics2D對象
Random random=new Random();
Font mfont=new Font("楷體",Font.BOLD,20); //定義字體樣式
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height); //繪制背景
g.setFont(mfont); //設置字體
g.setColor(getRandColor(180,200));
//繪制100條顏色和位置全部為隨機產生的線條,該線條為2f
for(int i=0;i<100;i++){
int x=random.nextInt(width-1);
int y=random.nextInt(height-1);
int x1=random.nextInt(6)+1;
int y1=random.nextInt(12)+1;
BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL); //定制線條樣式
Line2D line=new Line2D.Double(x,y,x+x1,y+y1);
g2d.setStroke(bs);
g2d.draw(line); //繪制直線
}
//輸出由英文，數字，和中文隨機組成的驗證文字，具體的組合方式根據生成隨機數確定。
String sRand="";
String ctmp="";
int itmp=0;
//制定輸出的驗證碼為四位
for(int i=0;i<4;i++){
switch(random.nextInt(3)){
case 1: //生成A-Z的字母
itmp=random.nextInt(26)+65;
ctmp=String.valueOf((char)itmp);
break;
default:
itmp=random.nextInt(10)+48;
ctmp=String.valueOf((char)itmp);
break;
}
sRand+=ctmp;
Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),random.nextInt(110));
g.setColor(color);
//將生成的隨機數進行隨機縮放并旋轉制定角度 PS.建議不要對文字進行縮放與旋轉,因為這樣圖片可能不正常顯示
/*將文字旋轉制定角度*/
Graphics2D g2d_word=(Graphics2D)g;
AffineTransform trans=new AffineTransform();
trans.rotate((45)*3.14/180,15*i+8,7);
/*縮放文字*/
float scaleSize=random.nextFloat()+0.8f;
if(scaleSize>1f) scaleSize=1f;
trans.scale(scaleSize, scaleSize);
g2d_word.setTransform(trans);
g.drawString(ctmp, 15*i+18, 14);
}
HttpSession session=request.getSession(true);
session.setAttribute("randCheckCode", sRand);
g.dispose(); //釋放g所占用的系統資源
ImageIO.write(image,"JPEG",response.getOutputStream()); //輸出圖片
}
}配置web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>web04</display-name> <welcome-file-list> <welcome-file>login.jsp</welcome-file> <welcome-file>main.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>com.ningmeng.web.LoginServlet</servlet-class> </servlet> <servlet> <description>輸出驗證碼</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>PictureCheckCode</servlet-name> <servlet-class>com.servlet.PictureCheckCode</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/login</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>PictureCheckCode</servlet-name> <url-pattern>/PictureCheckCode</url-pattern> </servlet-mapping> </web-app>
login.jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script language="javascript">
function myReload() {
document.getElementById("CreateCheckCode").src = document
.getElementById("CreateCheckCode").src
+ "?nocache=" + new Date().getTime();
}
</script>
</head>
<body>
<form action="login" method="post">
<table>
<tr>
<th colspan="2">登錄界面</th>
</tr>
<tr>
<td>賬號：</td>
<td><input type="text" id="username" name="username" value="${username}"></td>
</tr>
<tr>
<td>密碼：</td>
<td><input type="password" id="password" name="password" value="${password}"></td>
</tr>
<tr>
<td>驗證碼：</td>
<td><input name="checkCode" type="text" id="checkCode" title="驗證碼區分大小寫"
size="8" ,maxlength="4" />
<img src="PictureCheckCode" id="CreateCheckCode" align="middle">
<a href="" onclick=" rel="external nofollow" myReload()"> 看不清,換一個</a>
</tr>
<tr>
<td>類型：</td>
<td>
<input type="radio" name="ra" value="l" checked="checked"/>一般研究人員
<input type="radio" name="ra" value="m" />管理員研究人員
</td>
</tr>
<tr>
<td>
<input type="submit" value="提交">
<font color="red">${error}</font>
</td>
</tr>
</table>
</form>
</body>
</html>main.jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<p>登錄成功</p>
當前用戶：${currentUser.username}<br/>
當前密碼：${currentUser.password}<br/>
</body>
</html>linmao.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>" rel="external nofollow" > <title>My JSP 'linmao.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" > --> </head> <body> This is my JSP page. <br> </body> </html>
項目現在做到驗證碼和權限這一塊，找回密碼功能還沒有做完，結構中Check.jsp還用不到。還有連接數據庫的操作，就不詳細敘述了。
看完上述內容，你們對Java web如何實現一個驗證碼權限登錄功能有進一步的了解嗎？如果還想了解更多知識或者相關內容，請關注億速云行業資訊頻道，感謝大家的支持。
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