JAVA验证码工具实例代码
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2022-03-10 10:51:31
工具类:
package com.lhy.web.servlet;
import java.awt.basicstroke;
import java.awt....
工具类:
package com.lhy.web.servlet; import java.awt.basicstroke; import java.awt.color; import java.awt.font; import java.awt.graphics2d; import java.awt.image.bufferedimage; import java.io.filenotfoundexception; import java.io.fileoutputstream; import java.io.ioexception; import java.io.outputstream; import java.util.random; import javax.imageio.imageio; public class verifycode { private int w = 70;//图片长 private int h = 35;//图片宽 private random r = new random();//random类 生成随机数 // 列举验证图片中验证码的字体类型 //{"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_gb2312"} private string[] fontnames = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_gb2312"}; // 验证码可选字符 private string codes="23456789abcdefghjkmnopqrstuvwxyzabcdefghjkmnpqrstuvwxyz"; // 背景色 private color bgcolor = new color(255, 255, 255); // 验证码上的文本 private string text ; // 生成随机的颜色 private color randomcolor () { int red = r.nextint(150); int green = r.nextint(150); int blue = r.nextint(150); return new color(red, green, blue); } // 生成随机的字体 private font randomfont () { int index = r.nextint(fontnames.length); string fontname = fontnames[index];//生成随机的字体名称 int style = r.nextint(4);//生成随机的样式, 0(无样式), 1(粗体), 2(斜体), 3(粗体+斜体) int size = r.nextint(5) + 24; //生成随机字号, 24 ~ 28 return new font(fontname, style, size); } // 画干扰线 private void drawline (bufferedimage image) { int num = 3;//一共画3条 graphics2d g2 = (graphics2d)image.getgraphics(); for(int i = 0; i < num; i++) {//生成两个点的坐标,即4个值 int x1 = r.nextint(w); int y1 = r.nextint(h); int x2 = r.nextint(w); int y2 = r.nextint(h); g2.setstroke(new basicstroke(1.5f)); g2.setcolor(color.blue); //干扰线是蓝色 g2.drawline(x1, y1, x2, y2);//画线 } } // 随机生成一个字符 private char randomchar () { int index = r.nextint(codes.length()); return codes.charat(index); } // 创建bufferedimage private bufferedimage createimage () { //宽,高,图片的类型 bufferedimage image = new bufferedimage(w, h, bufferedimage.type_int_rgb); graphics2d g2 = (graphics2d)image.getgraphics(); g2.setcolor(this.bgcolor); g2.fillrect(0, 0, w, h); return image; } // 返回验证码图片上的文本 public string gettext () { return text; } // 保存图片到指定的输出流 public static void output (bufferedimage image, outputstream out) throws ioexception { imageio.write(image, "jpeg", out); } // 调用这个方法得到验证码 public bufferedimage getimage () { bufferedimage image = createimage();//创建图片缓冲区 graphics2d g2 = (graphics2d)image.getgraphics();//得到绘制环境 stringbuilder sb = new stringbuilder();//用来装载生成的验证码文本 // 向图片中画4个字符 for(int i = 0; i < 4; i++) {//循环四次,每次生成一个字符 string s = randomchar() + "";//随机生成一个字母 sb.append(s); //把字母添加到sb中 float x = i * 1.0f * w / 4; //设置当前字符的x轴坐标 g2.setfont(randomfont()); //设置随机字体 g2.setcolor(randomcolor()); //设置随机颜色 g2.drawstring(s, x, h-5); //画图 } this.text = sb.tostring(); //把生成的字符串赋给了this.text drawline(image); //添加干扰线 return image; } public static void main(string[] args) throws filenotfoundexception, ioexception { verifycode vc = new verifycode();//创建verifycode类的对象 bufferedimage bi = vc.getimage();//调用getimge()方法获得一个bufferedimage对象 verifycode.output(bi, new fileoutputstream("c:/验证码3.jpg"));//调用静态方法output()方法将图片保存在文件输出流中 system.out.println(vc.gettext());//在控制台上打印验证码的文本值 } }
verifycodeservlet:
package com.lhy.web.servlet; import java.awt.image.bufferedimage; import java.io.ioexception; import javax.servlet.servletexception; import javax.servlet.http.httpservlet; import javax.servlet.http.httpservletrequest; import javax.servlet.http.httpservletresponse; public class verifycodeservlet extends httpservlet { public void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { /* * 1. 生成图片 * 2. 保存图片上的文本到session域中 * 3. 把图片响应给客户端 */ verifycode vc = new verifycode(); bufferedimage image = vc.getimage(); request.getsession().setattribute("session_vcode", vc.gettext());//保存图片上的文本到session域 verifycode.output(image, response.getoutputstream()); } }
loginservlet:
package com.lhy.web.servlet; import java.io.ioexception; import javax.servlet.requestdispatcher; import javax.servlet.servletexception; import javax.servlet.http.cookie; import javax.servlet.http.httpservlet; import javax.servlet.http.httpservletrequest; import javax.servlet.http.httpservletresponse; import javax.servlet.http.httpsession; public class loginservlet extends httpservlet { public void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { /* * 校验验证码 * 1. 从session中获取正确的验证码 * 2. 从表单中获取用户填写的验证码 * 3. 进行比较! * 4. 如果相同,向下运行,否则保存错误信息到request域,转发到login.jsp */ string sessioncode = (string) request.getsession().getattribute("session_vcode"); string paramcode = request.getparameter("verifycode"); if(!paramcode.equalsignorecase(sessioncode)) { request.setattribute("msg", "验证码错误!"); request.getrequestdispatcher("/login.jsp").forward(request, response); return; } /* * 1. 获取表单数据 */ // 处理中文问题 request.setcharacterencoding("utf-8"); // 获取 string username = request.getparameter("username"); string password = request.getparameter("password"); /* * 2. 校验用户名和密码是否正确 */ if("itcast".equalsignorecase(username)) {//登录成功 /* * 附加项:把用户名保存到cookie中,发送给客户端浏览器 * 当再次打开login.jsp时,login.jsp中会读取request中的cookie,把它显示到用户名文本框中 */ cookie cookie = new cookie("uname", username);//创建cookie cookie.setmaxage(60*60*24);//设置cookie命长为1天 response.addcookie(cookie);//保存cookie /* * 3. 如果成功 * > 保存用户信息到session中 * > 重定向到succ1.jsp */ httpsession session = request.getsession();//获取session session.setattribute("username", username);//向session域中保存用户名 response.sendredirect("/test/succ1.jsp"); } else {//登录失败 /* * 4. 如果失败 * > 保存错误信息到request域中 * > 转发到login.jsp */ request.setattribute("msg", "用户名或密码错误!"); requestdispatcher qr = request.getrequestdispatcher("/login.jsp");//得到转发器 qr.forward(request, response);//转发 } } }
login.jsp:
<%@ page language="java" import="java.util.*" pageencoding="utf-8"%> <%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 'login.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" > --> <script type="text/javascript"> function _change() { /* 1. 得到img元素 2. 修改其src */ var imgele = document.getelementbyid("img"); imgele.src = "<%=basepath%>servlet/verifycodeservlet?a=" + new date().gettime(); } </script> </head> <body> <%-- 本页面提供登录表单,还要显示错误信息 --%> <h1>登录</h1> <% /* 读取名为uname的cookie! 如果为空显示:"" 如果不为空显示:cookie的值 */ string uname = ""; cookie[] cs = request.getcookies();//获取请求中所有的cookie if(cs != null) {// 如果存在cookie for(cookie c : cs) {//循环遍历所有的cookie if("uname".equals(c.getname())) {//查找名为uname的cookie uname = c.getvalue();//获取这个cookie的值,给uname这个变量 } } } %> <% string message = ""; string msg = (string)request.getattribute("msg");//获取request域中的名为msg的属性 if(msg != null) { message = msg; } %> <font color="red"><b><%=message %> </b></font> <form action="servlet/loginservlet" method="post"> <%-- 把cookie中的用户名显示到用户名文本框中 --%> 用户名:<input type="text" name="username" value="<%=uname%>"/><br/> 密 码:<input type="password" name="password"/><br/> 验证码:<input type="text" name="verifycode" size="3"/> <img id="img" src="<%=basepath%>servlet/verifycodeservlet"/> <a href="javascript:_change()" rel="external nofollow" >换一张</a> <br/> <input type="submit" value="登录"/> </form> </body> </html>
loginsuccess:
<body> <h1>succ1</h1> <% string username = (string)session.getattribute("username"); if(username == null) { /* 1. 向request域中保存错误信息,转发到login.jsp */ request.setattribute("msg", "您还没有登录!请先登录!"); request.getrequestdispatcher("/login.jsp").forward(request, response); return; } %>
欢迎欢迎,热烈欢迎,欢迎<%=username %>
领导指导工作!
</body> </html>
配置文件:
<servlet> <servlet-name>loginservlet</servlet-name> <servlet-class>com.lhy.web.servlet.loginservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>loginservlet</servlet-name> <url-pattern>/servlet/loginservlet</url-pattern> </servlet-mapping> <servlet> <servlet-name>verifycodeservlet</servlet-name> <servlet-class>com.lhy.web.servlet.verifycodeservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>verifycodeservlet</servlet-name> <url-pattern>/servlet/verifycodeservlet</url-pattern> </servlet-mapping>
建议:生成验证码的servlet最好设置成不缓存,这样就不用再页面请求验证码图片的时候加上时间戳了,加上时间戳就是欺骗浏览器防止浏览器读取缓存里的验证码图片,而点击换一张后没反应。 这样的不是很好的一点就是,每次点击换一张,浏览器都会把新获取的图片缓存到本地,而在servlet里设置不缓存,就不会缓存到本地了。
总结
以上所述是小编给大家介绍的java验证码工具实例代码,希望对大家有所帮助
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