博客部分内容转载自 LonlySnow的博客：后台java 实现验证码生成
1、controller方法
@RequestMapping(value = "/verifycode/img", method = RequestMethod.GET)
@ApiOperation("generate image verification code")
public void generateImgVerificationCode(HttpServletRequest request, HttpServletResponse response) { try {
// int width = 200;
// int height = 69;
int width = 129;
int height = 40;
BufferedImage verifyImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 生成对应宽高的初始图片
// 生成验证码字符并加上噪点，干扰线，返回值为验证码字符
String randomText = UtilFunctions.drawRandomText(width, height, verifyImg); request.getSession().setAttribute("img_verify_code", randomText.toUpperCase());
request.getSession().setAttribute("img_verify_time", System.currentTimeMillis()); response.setContentType("image/png"); // 必须设置响应内容类型为图片，否则前台不识别
OutputStream os = response.getOutputStream(); // 获取文件输出流
ImageIO.write(verifyImg, "png", os); // 输出图片流 os.flush();
os.close();
} catch (Exception e) {
UtilFunctions.log.error("msg: {}, exception: {}", e.toString(), e);
UtilFunctions.reportError(e.toString(), e);
}
}
2、生成图片的方法
public static String drawRandomText(int width, int height, BufferedImage verifyImg) {
Graphics2D graphics = (Graphics2D) verifyImg.getGraphics();
graphics.setColor(Color.WHITE);// 设置画笔颜色-验证码背景色
graphics.fillRect(0, 0, width, height);// 填充背景
// graphics.setFont(new Font("微软雅黑", Font.BOLD, 40));
graphics.setFont(new Font("微软雅黑", Font.BOLD, 30));
// 数字和字母的组合
//String baseNumLetter = "123456789abcdefghijklmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ";
//String baseNumLetter = "2345678abcdefhijkmnpqrstuvwxyzABCDEFGHJKLMNPQRTUVWXY";
String baseNumLetter = "123456789";
StringBuffer sBuffer = new StringBuffer();
int x = 10; // 旋转原点的 x 坐标
String ch = "";
Random random = new Random();
Color textColor = getRandomColor();
for (int i = 0; i < 4; i++) {
// graphics.setColor(getRandomColor());
graphics.setColor(textColor);
// 设置字体旋转角度
int degree = random.nextInt() % 30; // 角度小于30度
int dot = random.nextInt(baseNumLetter.length());
ch = baseNumLetter.charAt(dot) + "";
sBuffer.append(ch);
// 正向旋转
graphics.rotate(degree * Math.PI / 180, x, 45);
//graphics.drawString(ch, x, 45);
graphics.drawString(ch, x, 30);
// 反向旋转
graphics.rotate(-degree * Math.PI / 180, x, 45);
//x += 48;
x += 30;
}
// 画干扰线
for (int i = 0; i < 6; i++) {
// 设置随机颜色
graphics.setColor(getRandomColor());
// 随机画线
graphics.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width),
random.nextInt(height));
}
// 添加噪点
// for (int i = 0; i < 30; i++) {
// int x1 = random.nextInt(width);
// int y1 = random.nextInt(height);
// graphics.setColor(getRandomColor());
// graphics.fillRect(x1, y1, 2, 2);
// }
return sBuffer.toString();
}
private static Color getRandomColor() {
Random ran = new Random();
Color color = new Color(ran.nextInt(256), ran.nextInt(256), ran.nextInt(256));
return color;
}
3、效果
==========================================================
4、 使用java来画图的api
// 得到图片缓冲区
BufferedImage bi = new BufferedImage(150, 70, BufferedImage.TYPE_INT_RGB);
// 得到它的绘制环境（画图的笔）
Graphics2D g2 = (Graphics2D) bi.getGraphics(); g2.setColor(Color.WHITE);// 设置画笔颜色，即后面背景色为白色
g2.fillRect(0, 0, 150, 70);// 填充整张图片(其实就是设置背景色) g2.setColor(Color.BLUE);// 设置画笔颜色，即后面边框颜色为蓝色
g2.drawRect(0, 0, 150 - 1, 70 - 1);// 设置边框 g2.setFont(new Font("宋体", Font.BOLD, 18));// 设置字体名称、样式、字号
g2.setColor(Color.BLACK);// 设置画笔颜色，即后面字符串颜色为黑色
g2.drawString("HelloWorld", 20, 40);// 设置字符"H"左下角坐标，向图片上写字符串 ImageIO.write(bi, "JPEG", new FileOutputStream("D:/a.jpg"));// 保存图片
5、生成验证码图片的工具类VerifyCode
package com.oy.demo; import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random; import javax.imageio.ImageIO; public class VerifyCode {
private int w = 70;
private int h = 35;
private Random r = new Random();
// {"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"};
//可选字符
private String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
//背景色
private Color bgColor = new Color(255, 255, 255);
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);
} //生成随机字体
private Font randomFont () {
int index = r.nextInt(fontNames.length);
String fontName = fontNames[index];
int style = r.nextInt(4); //生成随机样式，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
return new Font(fontName, style, size);
} //画干扰线
private void drawLine (BufferedImage image) {
int num = 3; //总共画三条干扰线
Graphics2D g2 = (Graphics2D)image.getGraphics();
for(int i = 0; i < num; i++) { //生成两个点的左边，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); //设置干扰线颜色为蓝色
g2.drawLine(x1, y1, x2, y2);
}
} //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 () {
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;
} public BufferedImage getImage () {
BufferedImage image = createImage(); //创建图片缓冲区
Graphics2D g2 = (Graphics2D)image.getGraphics();//得到绘制环境，画笔
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++) {
String s = randomChar() + ""; //随机生成一个字符
sb.append(s);
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this.text
drawLine(image); //添加干扰线
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);
}
}
VerifyCode的使用
@Test
public void fun() throws FileNotFoundException, IOException {
VerifyCode verifyCode = new VerifyCode();
BufferedImage bi = verifyCode.getImage();// 随机的
System.out.println(verifyCode.getText());// 打印图片上的文本内容
VerifyCode.output(bi, new FileOutputStream("d:/b.jpg"));
}
创建一个Servlet：使用VerifyCode返回图片验证码
public class VerifyCodeServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* a、生成图片； b、保存图片上的文本到session域中； c、把图片响应给客户端。
*/
VerifyCode vc = new VerifyCode();
BufferedImage bi = vc.getImage(); // 生成图片
request.getSession().setAttribute("session_verifyCode", vc.getText()); // 保存图片上的文本到session域中
VerifyCode.output(bi, response.getOutputStream());// 把图片响应给客户端
}
}
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%>"> <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">
--> </head> <body>
<h2>登录页面</h2> <%
/*
* 查找名为"uname"的Cookie,如果存在，将该Cookie的值赋给变量uname
*/
String uname="";
Cookie[] cs=request.getCookies(); //获取所有Cookie
if(null!=cs){ //如果存在Cookie
for(Cookie c:cs){ //遍历所有Cookie
if("uname".equals(c.getName())){ //查找名为"uname"的Cookie
uname=c.getValue(); //把名为"uname"的Cookie的值赋给变量uname
}
}
}
%> <!-- 显示登录错误信息 -->
<div style="color:red;">
<%
String msg=(String)request.getAttribute("msg");
if(null!=msg){
out.print(msg);
}
%>
</div> <%
String message_verifyCode="";
String msg_verifyCode=(String)request.getAttribute("msg_verifyCode");
if(null!=msg_verifyCode){
message_verifyCode=msg_verifyCode;
}
%> <!-- 如果存在名为"uname"的Cookie，将其该Cookie的值输出到用户名文本框 -->
<form action="/day11_2/LoginServlet" method="post">
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" size="4" name="verifyCode"/>
<img id="id_img" src="/day11_2/VerifyCodeServlet"/>
<a href="javascript:_change()">看不清，换一张</a>
<span style="color:red"><%= message_verifyCode %></span>
<br/>
<input type="submit" value="登录"/>
</form> </body> <script type="text/javascript">
function _change(){
//获取<img>元素对象
var imgEle=document.getElementById("id_img");
//给<img>元素的src属性赋值为"/day11_2/VerifyCodeServlet"
//"?a="+new Date().getTime()是为了防止浏览器缓存的影响
imgEle.src="/day11_2/VerifyCodeServlet?a="+new Date().getTime();
//alert(1);//用来测试代码 }
</script>
</html>
效果：