JAVA验证码工具实例代码

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