java生成图片验证码

public class RandomVerificationCode {

private StringBuffer stringBuffer = new StringBuffer();

private RandomVerificationCode() {
}

private static final Random random = new Random();
private String randomString = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";// 随机产生的字符串
private static String randomNumber = "0123456789";// 随机产生的验证码

private int width;//图片宽
private int height;//图片高
private int lineNum;//干扰线数量
private int codeNum;//验证码长度
private int textSize;//字号

/**
* 获得字体
*/
private Font getFont() {
//字体，风格，字号
return new Font("Clanner", Font.CENTER_BASELINE, textSize);
}

/**
* 随机生成验证码
*/
public static String getRandomNumber(int n){
StringBuffer stringBuffer = new StringBuffer();
for (int i = 0;i < n;i++){
stringBuffer.append(String.valueOf
(randomNumber.charAt(random.nextInt(randomNumber.length()))));
}
return stringBuffer.toString();
}

/**
* 获得颜色
*/
private Color getRandColor(int fc, int bc) {
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc - 16);
int g = fc + random.nextInt(bc - fc - 14);
int b = fc + random.nextInt(bc - fc - 18);
return new Color(r, g, b);
}

/**
* 绘制字符串
* @param g
* @param randomString 要绘制的字符
* @param i 该字符的位置
* @return
*/
private String drawString(Graphics g, String randomString, int i) {
g.setFont(getFont());
g.setColor(new Color(random.nextInt(101),
random.nextInt(111), random.nextInt(121)));
g.translate(random.nextInt(3), random.nextInt(3));
g.drawString(randomString, 13 * i, 16);
return randomString;
}

/**
* 绘制干扰线
*/
private void drawLine(Graphics g) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(13);
int yl = random.nextInt(15);
g.setColor(new Color(random.nextInt(101),
random.nextInt(111), random.nextInt(121)));
g.drawLine(x, y, x + xl, y + yl);
}

/**
* 生成随机图片
* @param request
* @param response
* @param key 保存在session中的键值
*/
public void getRandomImage(HttpServletRequest request, HttpServletResponse response, String key) {

// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,该对象可以在图像上进行各种绘制操作
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
g.setColor(getRandColor(110, 133));
// 绘制干扰线
for (int i = 0; i <= lineNum; i++) {
drawLine(g);
}
// 绘制随机字符
for (int i = 0; i < codeNum; i++) {
stringBuffer.append(drawString
(g, String.valueOf
(this.randomString.charAt(random.nextInt(this.randomString.length()))), i));
}
String randomString = stringBuffer.toString();
request.getSession().setAttribute(key, randomString);
System.out.println("验证码是"+randomString);

g.dispose();
try {
ByteArrayOutputStream tmp = new ByteArrayOutputStream();
ImageIO.write(image, "png", tmp);
tmp.close();
Integer contentLength = tmp.size();
response.setHeader("content-length", contentLength + "");
response.getOutputStream().write(tmp.to
4000
ByteArray());// 将内存中的图片通过流动形式输出到客户端
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.getOutputStream().flush();
response.getOutputStream().close();
} catch (Exception e2) {
e2.printStackTrace();
}
}
}

public static class Builder {
private int width = 80;//图片宽
private int height = 26;//图片高
private int lineNum = 40;//干扰线数量
private int codeNum = 4;//验证码长度
private int textSize = 18;//字号

public Builder setWidth(int width) {
this.width = width;
return this;
}

public Builder setHeight(int height) {
this.height = height;
return this;
}

public Builder setLineNum(int lineNum) {
this.lineNum = lineNum;
return this;
}

public Builder setCodeNum(int codeNum) {
this.codeNum = codeNum;
return this;
}

public Builder setTextSize(int textSize) {
this.textSize = textSize;
return this;
}

public RandomVerificationCode build() {
RandomVerificationCode randomVerificationCode = new RandomVerificationCode();
randomVerificationCode.width = width;
randomVerificationCode.height = height;
randomVerificationCode.lineNum = lineNum;
randomVerificationCode.codeNum = codeNum;
randomVerificationCode.textSize = textSize;
return randomVerificationCode;
}
}
}

/**
* 获取验证码
*/
public void getVerificationCode(HttpServletResponse response,
HttpServletRequest request) {
response.setContentType("image/jpeg");// 设置相应类型,告诉浏览器输出的内容为图片
response.setHeader("Pragma", "No-cache");//设置响应头信息，告诉浏览器不要缓存此内容
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Set-Cookie", "name=value; HttpOnly");//设置HttpOnly属性,防止Xss攻击
response.setDateHeader("Expire", 0);
new RandomVerificationCode.Builder().build().getRandomImage(request, response, "imageCode");
}

/**
* 验证验证码
*/
private boolean checkVerificationCode(String verificationCode, HttpSession session) {
String code = (String) session.getAttribute("imageCode");
System.out.println("DEBUG" + code);
if (verificationCode.equalsIgnoreCase(code)) {
session.removeAttribute("imageCode");
return true;
} else {
return false;
}
}