這是一個登陸頁面,有登陸驗證和驗證碼的功能
(1)生成驗證碼的servlet:
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;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
public class YzmServlet extends HttpServlet {
//設置驗證碼圖片的寬度
private static final int WIDTH = 100;
//設置驗證碼的高度
private static final int HEIGHT = 80;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//產生一張圖片
BufferedImage image=new BufferedImage(Width,Height,BufferedImage.TYPE_INT_RGB);
response.setHeader("Pragram","no-cache");
response.setHeader("Cache-Control","no-catch");
response.setDateHeader("Exprires",0);
Graphics g=image.getGraphics();
//設置背景顏色
g.setColor(Color.WHITE);
//填充圖片
g.fillRect(0,0,Width,Height);
//設置驗證碼顏色
g.setColor(Color.RED);
//設置驗證碼字體及大小
Font font=new Font("微軟雅黑",Font.BOLD,20);
//獲取驗證碼
String str=getRandomString(4);
//獲取session
HttpSession session=request.getSession();
//給str做標記
session.setAttribute("str",str);
//在圖片中畫出驗證碼
g.drawString(str,50,50);
//在圖片中隨機劃線
for (int i=0;i<15;i++){
int x1= RandomUtils.nextInt(0,Width);
int x2=RandomUtils.nextInt(0,Width);
int y1=RandomUtils.nextInt(0,Height);
int y2=RandomUtils.nextInt(0,Height);
Color color=new Color(RandomUtils.nextInt(0,255),RandomUtils.nextInt(0,255),RandomUtils.nextInt(0,255));
g.setColor(color);
g.drawLine(x1,y1,x2,y2);
}
//輸出圖片
ImageIO.write(image,"jpg",response.getOutputStream());
}}
(2)登陸驗證的servlet:
import org.apache.commons.lang3.RandomUtils;
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 java.io.IOException;
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
request.setCharacterEncoding("utf-8");
//獲取輸入的驗證碼的值
String yzm=request.getParameter("yzm");
//獲取輸入的用戶名
String username=request.getParameter("username");
//獲取輸入的密碼
String userpassword=request.getParameter("userpassword");
//獲取session
HttpSession session=request.getSession();
//獲取session標記的值,即服務端生成的驗證碼的值
String yzm2=(String) session.getAttribute("str");
//比較驗證碼
if (yzm.equals(yzm2)){
if(username.equals("zhangsan")&&userpassword.equals("123456")){
response.getWriter().print("登陸成功");
}else{
response.getWriter().print("用戶名或密碼錯誤");
}
}else{
response.getWriter().print("驗證碼錯誤");
}
}}
(3)登陸界面(比較簡陋)
<html lang="en">
<head>
<meta charset="UTF-8">
<title>登陸</title>
</head>
<script type="text/javascript">
function refreshImg() {
document.getElementById("y").src="./Yzm";
}
</script>
<body>
<table width="760px" height="100%" align="center" style="background-color: azure">
<tr>
<td>
<div align="center"></div>
<table width="200" height="300">
<tr>
<td>
<form action="./Login" name="form1" method="post">
用戶名:<input type="text" name="username">
密 碼:<input type="password" name="userpassword">
<a>
<img id="y" name="y" src="./Yzm" height="100" onclick="refreshImg()">
</a>
<button type="submit" value="看不清?" style="background-color: red" onclick="refreshImg()">看不清?</button><br>
驗證碼:<input type="text" name="yzm" id="yzm" style="width: 30px" onclick="refreshImg()"><br>
<button type="submit" onclick="check()">提交</button>
<button type="reset">重置</button>
</form>
</td>
</tr>
</table>
</div>
</td>
</tr></table>
</body>
</html>
(4)配置web.xml
<?xml version="1.0" encoding="utf-8"?>