欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

JSP + Servlet实现生成登录验证码示例

程序员文章站 2023-01-03 23:27:27
随机生成四位数验证码,包括汉字,数字,英文大小写。 1.servlet类 package servlet; import java.awt.basicst...

随机生成四位数验证码,包括汉字,数字,英文大小写。

1.servlet类

package servlet;

import java.awt.basicstroke;
import java.awt.color;
import java.awt.font;
import java.awt.graphics;
import java.awt.graphics2d;
import java.awt.geom.affinetransform;
import java.awt.geom.line2d;
import java.awt.image.bufferedimage;
import java.io.ioexception;
import java.io.printwriter;
import java.util.random;

import javax.imageio.imageio;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import javax.servlet.http.httpsession;

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(); 
    } 
    /*该方法主要作用是获得随机生成的颜色*/  
    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);  //随机生成rgb颜色中的r值 
      g=s+random.nextint(e-s);  //随机生成rgb颜色中的g值 
      b=s+random.nextint(e-s);  //随机生成rgb颜色中的b值 
      return new color(r,g,b); 
    } 

  public void doget(httpservletrequest request, httpservletresponse response)
      throws servletexception, ioexception {
    system.out.println("this is doget method");
    this.dopost(request, response);

  }

  public void dopost(httpservletrequest request, httpservletresponse response)
      throws servletexception, ioexception {

    //设置不缓存图片 
    response.setheader("pragma", "no-cache"); 
    response.setheader("cache-control", "no-cache"); 
    response.setdateheader("expires", 0); 
    //指定生成的响应图片,一定不能缺少这句话,否则错误. 
    response.setcontenttype("image/jpeg"); 
    int width=80,height=35;   //指定生成验证码的宽度和高度 
    bufferedimage image=new bufferedimage(width,height,bufferedimage.type_int_rgb); //创建bufferedimage对象,其作用相当于一图片 
    graphics g=image.getgraphics();   //创建graphics对象,其作用相当于画笔 
    graphics2d g2d=(graphics2d)g;    //创建grapchics2d对象 
    random random=new random(); 
    font mfont=new font("楷体",font.bold,16); //定义字体样式 
    g.setcolor(getrandcolor(200,250)); 
    g.fillrect(0, 0, width, height);  //绘制背景 
    g.setfont(mfont);          //设置字体 
    g.setcolor(getrandcolor(180,200)); 

    //绘制100条颜色和位置全部为随机产生的线条,该线条为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); //定制线条样式 
      line2d line=new line2d.double(x,y,x+x1,y+y1); 
      g2d.setstroke(bs); 
      g2d.draw(line);   //绘制直线 
    } 
    //输出由英文,数字,和中文随机组成的验证文字,具体的组合方式根据生成随机数确定。 
    string srand=""; 
    string ctmp=""; 
    int itmp=0; 
    //制定输出的验证码为四位 
    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; 
        case 2:   //生成汉字 
           string[] rbase={"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"};  
           //生成第一位区码 
           int r1=random.nextint(3)+11; 
           string str_r1=rbase[r1]; 
           //生成第二位区码 
           int r2; 
           if(r1==13){ 
             r2=random.nextint(7);   
           }else{ 
             r2=random.nextint(16); 
           } 
           string str_r2=rbase[r2]; 
           //生成第一位位码 
           int r3=random.nextint(6)+10; 
           string str_r3=rbase[r3]; 
           //生成第二位位码 
           int r4; 
           if(r3==10){ 
             r4=random.nextint(15)+1; 
           }else if(r3==15){ 
             r4=random.nextint(15); 
           }else{ 
             r4=random.nextint(16); 
           } 
           string str_r4=rbase[r4]; 
           //将生成的机内码转换为汉字 
           byte[] bytes=new byte[2]; 
           //将生成的区码保存到字节数组的第一个元素中 
           string str_12=str_r1+str_r2; 
           int templow=integer.parseint(str_12, 16); 
           bytes[0]=(byte) templow; 
           //将生成的位码保存到字节数组的第二个元素中 
           string str_34=str_r3+str_r4; 
           int temphigh=integer.parseint(str_34, 16); 
           bytes[1]=(byte)temphigh; 
           ctmp=new string(bytes); 
           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); 
      //将生成的随机数进行随机缩放并旋转制定角度 ps.建议不要对文字进行缩放与旋转,因为这样图片可能不正常显示 
      /*将文字旋转制定角度*/ 
      graphics2d g2d_word=(graphics2d)g; 
      affinetransform trans=new affinetransform(); 
      trans.rotate((45)*3.14/180,15*i+8,7); 
      /*缩放文字*/ 
      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); 
    system.out.println(srand);
    g.dispose();  //释放g所占用的系统资源 
    imageio.write(image,"jpeg",response.getoutputstream()); //输出图片 
  }

}

2.web.xml配置

<servlet>
  <description>this is the description of my j2ee component</description>
  <display-name>this is the display name of my j2ee component</display-name>
  <servlet-name>picturecheckcode</servlet-name>
  <servlet-class>servlet.picturecheckcode</servlet-class>
 </servlet>

<servlet-mapping>
  <servlet-name>picturecheckcode</servlet-name>
  <url-pattern>/picturecheckcode</url-pattern>
 </servlet-mapping>

3.jsp页面输出验证码

<%@ page language="java" import="java.util.*" pageencoding="utf-8"%>

<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>

<title>登录页面</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">
<script language="javascript">
  function myreload() {
    document.getelementbyid("createcheckcode").src = document
        .getelementbyid("createcheckcode").src
        + "?nocache=" + new date().gettime();
  }
</script>

</head>

<body>
  <form action="loginservlet" method="get">
      <p class="font tdheight">
        验证码:<input type="text" name="checkcode"
          style="width:70px;height:35px;"> <img
          src="picturecheckcode" id="createcheckcode" align="middle"
          style="margin-top:-10px;"> <br> <a href=""
          onclick="myreload()"
          style="font-size:12px;color:red;margin-left:156px;"> 看不清,换一个</a>
      </p>
      <br><input type="submit" value="提交"
            class="font" style="width:240px;height:35px;background:#f19e28">

    </form>
</body>
</html>

4.后台servlet判断验证码是否与输入一致

通过request.getparameter(“checkcode”)获取输入验证码,与session.getattribute(“randcheckcode”)比较是否一致。

public void doget(httpservletrequest request, httpservletresponse response)
      throws servletexception, ioexception {

    string code = request.getparameter("checkcode");
    httpsession session = request.getsession();
    if (!code.equals(session.getattribute("randcheckcode"))) {
      request.setattribute("errormsg", "验证码不正确");
    } 
    system.out.println(request.getattribute("errormsg"));
  }

运行结果:

JSP + Servlet实现生成登录验证码示例

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。