简单实现Java验证码功能

今晚看到网上有关验证码的实现的代码，很早就想写一个了，感觉验证码挺有意思的，于是就写了一个，然而后来一直加载不出图片。尝试了很多方法，后来终于解决了，原来是我项目里面的 web.xml中没有部署servlet的映射，web.xml如下图：

运行效果如下：

代码如下：

package model; 
 
import javax.imageio.imageio; 
import java.awt.*; 
import java.awt.image.bufferedimage; 
import java.io.ioexception; 
import java.io.outputstream; 
import java.util.random; 
 
/** 
 * created by petty on 2017/5/4. 
 */ 
public class vcode { 
 
 private int w; //图片宽 
 private int h;//图片高 
 private color bgcolor = new color(240,240,240);//背景色 
 private random random = new random();//随机对象 
 //设置字体范围 
 private string[] fontnames = {"宋体","华文楷体","黑体","华文新魏","华文隶书","微软雅黑","楷体"}; 
 //设置字体样式范围 
 private int[] fontstyle = {0,1,2,3}; 
 //设置字号范围 
 private int[] fontsizes = {24,25,26,27,28}; 
 //设置所有字符串范围 
 private string codes="abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789"; 
 
 
 //无参数构造函数 
 public vcode(){ 
 
 } 
 
 //带宽和高的构造函数 
 public vcode(int w,int h){ 
  this.w = w; 
  this.h = h; 
 } 
 
 //返回一张背景图片 
 private bufferedimage createimage(){ 
  /** 
   * 1.创建图片 2.设置背景色 
   */ 
  //创建图片 
  bufferedimage img = new bufferedimage(w,h,bufferedimage.type_int_rgb); 
  //设置背景色 
  graphics g = img.getgraphics(); 
  g.setcolor(bgcolor); 
  g.fillrect(0,0,w,h); 
  return img; 
 } 
 
 
 // 随机返回字体颜色 
 private color randomcolor() { 
     int r = random.nextint(256); 
     int g = random.nextint(256); 
     int b = random.nextint(256); 
   return new color(r, g, b); 
   } 
 
 
 //随机返回字体样式 
 private font randomfont(){ 
  //随机生成字体下标，随机从给定的范围内获取一个字体 
  int index = random.nextint(fontnames.length); 
  string name = fontnames[index]; 
 
  //随机生成字体样式下标，随即从给定的范围内获取一个字体样式 
  index = random.nextint(fontstyle.length); 
  int style = fontstyle[index]; 
 
  //随机生成字体大小下标，随机从给定的范围内获取一个字体大小 
  index = random.nextint(fontsizes.length); 
  int size = fontsizes[index]; 
 
  return new font(name,style,size); 
 } 
 
 
 //随机返回字体内容 
 private string randomchar(){ 
  int index = random.nextint(codes.length()); 
 
  return codes.charat(index)+""; 
 } 
 
 
 //随机返回几条干扰线 
 private void getline(bufferedimage img){ 
  //设置干扰线的宽度为1.5倍宽，随机画五条 
  graphics2d g =(graphics2d) img.getgraphics(); 
  g.setcolor(color.black); 
  g.setstroke(new basicstroke(1.5f)); 
  for(int i=0;i<5;i++){ 
   int x1 = random.nextint(w); 
   int y1 = random.nextint(h); 
   int x2 = random.nextint(w); 
   int y2 = random.nextint(h); 
   g.drawline(x1,y1,x2,y2); 
  } 
 } 
 
 
 //用户调用该方法获取图片 
 public bufferedimage getimage(){ 
  /** 
   * 随机生成字符0-9a-za-z,设置字体，字号，是否粗体，字符颜色，都是随机的 
   */ 
  bufferedimage img = createimage(); 
 
  this.getline(img); 
 
  //获取画笔 
  graphics g = img.getgraphics(); 
 
  //画内容 
  for(int i=0;i<4;i++){ 
   g.setcolor(this.randomcolor());//获取随机颜色 
   g.setfont(this.randomfont());//获取随机字体 
   g.drawstring(this.randomchar(),w/4*i,h-5);//获取字符串随机内容 
  } 
  return img; 
 } 
 
 
 //用户调用该方法保存图片到本地 
 public void saveimage(bufferedimage img, outputstream ous){ 
 
  try { 
   imageio.write(img,"jpeg",ous); 
  } catch (ioexception e) { 
   e.printstacktrace(); 
  } 
 } 
}

package model; 
 
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.image.bufferedimage; 
import java.io.ioexception; 
 
/** 
 * created by petty on 2017/5/4. 
 */ 
@webservlet(name = "bservlet") 
public class bservlet extends httpservlet { 
 public void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { 
  vcode v = new vcode(70,35); 
  bufferedimage img = v.getimage(); 
  v.saveimage(img,response.getoutputstream()); 
 } 
 
 public void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { 
  vcode v = new vcode(70,35 ); 
  bufferedimage img = v.getimage(); 
  v.saveimage(img,response.getoutputstream()); 
 } 
} 

<%-- 
 created by intellij idea. 
 user: petty 
 date: 2017/5/4 
 time: 22:28 
 to change this template use file | settings | file templates. 
--%> 
<%@ page contenttype="text/html;charset=utf-8" language="java" %> 
<html> 
 <head> 
 <title>一次性验证码</title> 
 </head> 
 <body> 
 <form action="" method="get"> 
  <table align="center"> 
   <tr> 
    <td><img id="img" alt="" src="servlet/bservlet" onclick="changenext()"></td> 
   </tr> 
  </table> 
 </form> 
 </body> 
</html> 
<script type="text/javascript"> 
 function changenext(){ 
  var a=document.getelementbyid("img"); 
  a.src="servlet/bservlet?a="+new date().gettime(); 
 } 
</script>

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。