这是一个登陆页面,有登陆验证和验证码的功能
(1)生成验证码的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 {
//设置验证码图片的宽度
private static final int WIDTH = 100;
//设置验证码的高度
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 {
//产生一张图片
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();
//设置背景颜色
g.setColor(Color.WHITE);
//填充图片
g.fillRect(0,0,Width,Height);
//设置验证码颜色
g.setColor(Color.RED);
//设置验证码字体及大小
Font font=new Font("微软雅黑",Font.BOLD,20);
//获取验证码
String str=getRandomString(4);
//获取session
HttpSession session=request.getSession();
//给str做标记
session.setAttribute("str",str);
//在图片中画出验证码
g.drawString(str,50,50);
//在图片中随机划线
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);
}
//输出图片
ImageIO.write(image,"jpg",response.getOutputStream());
}}
(2)登陆验证的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");
//获取输入的验证码的值
String yzm=request.getParameter("yzm");
//获取输入的用户名
String username=request.getParameter("username");
//获取输入的密码
String userpassword=request.getParameter("userpassword");
//获取session
HttpSession session=request.getSession();
//获取session标记的值,即服务端生成的验证码的值
String yzm2=(String) session.getAttribute("str");
//比较验证码
if (yzm.equals(yzm2)){
if(username.equals("zhangsan")&&userpassword.equals("123456")){
response.getWriter().print("登陆成功");
}else{
response.getWriter().print("用户名或密码错误");
}
}else{
response.getWriter().print("验证码错误");
}
}}
(3)登陆界面(比较简陋)
(4)配置web.xml
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0"
metadata-complete="true">
Welcome to Tomcat
Welcome to Tomcat
LoginServlet
servlet.LoginServlet
LoginServlet
/Login
YzmServlet
servlet.YzmServlet
YzmServlet
/Yzm
界面还有一些问题,不能更换验证码.