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。