java创建图片验证码
package com;
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.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class ImgServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
private static Random random = new Random();
private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色
if(fc > 255)
fc=255;
if(bc > 255)
bc=255;
int r=fc + random.nextInt(bc - fc);
int g=fc + random.nextInt(bc - fc);
int b=fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
public void goRegister(HttpServletRequest request, HttpServletResponse response) {
// 设置页面不缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 在内存中创建图象
int width=100, height=40; // 图象大小
BufferedImage image=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics2D g=image.createGraphics();
g.setColor(new Color(255, 255, 255)); // 设定背景色
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman", Font.BOLD, 30)); // 设定字体
Color c = getRandColor(160, 200);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(c);
for(int i=0; i < 155; i++) {
int x=random.nextInt(width);
int y=random.nextInt(height);
int xl=random.nextInt(12);
int yl=random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
// 添加噪点
float yawpRate = 0.05f;// 噪声率
int area = (int) (yawpRate * width * height);
for (int i = 0; i < area; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int rgb = getRandomIntColor();
image.setRGB(x, y, rgb);
}
//随机生成不同的字体、字体样式和字体大小
String[] fontName = {"微软雅黑","黑体","Georgia","Verdana","Arial","Comic Sans MS","Lucida Console"};
int [] fontEffect = {Font.PLAIN, Font.ITALIC, Font.BOLD};
int [] fontSize = {28, 30, 32, 26};
Font[] fonts = new Font[fontName.length*fontEffect.length*fontSize.length];
int fontsIndex=0;
for(String str: fontName){
for(int effect: fontEffect){
for(int size : fontSize){
Font font = new Font(str, effect, size);
fonts[fontsIndex]=font;
fontsIndex = fontsIndex +1;
}
}
}
String s="abcdefghijknpqrstuvxyzABCDEFGHJKLNPQRSTUVXYZ23456789"; // 设置备选验证码
String sRand="";
// 用随机产生的颜色将验证码绘制到图像中。
int length = 4; // 设置默认生成4个验证码
for(int i=0;i<length;i++){
g.setColor(new Color(20+random.nextInt(110), 20+random.nextInt(110), 20+random.nextInt(110))); // 生成随机颜色(因为是做前景，所以偏深)
g.setFont(fonts[random.nextInt(fonts.length)]); //调用上方的随机字体
String ch=String.valueOf(s.charAt(random.nextInt(s.length())));
//设置字体旋转
int zhuan = random.nextInt(20);
int fzhuan = -random.nextInt(20);
g.rotate(Math.toRadians(zhuan),25*(i-1),20); /// 坐标系顺时针转
g.rotate(Math.toRadians(fzhuan),25*(i-1),20); /// 坐标系逆时针转
sRand+=ch;
g.drawString(ch, 18 * i + 15, 30); //将认证码用 drawString 函数显示到图象里
g.rotate(Math.toRadians(-1*zhuan),25*(i-1),20);
g.rotate(Math.toRadians(-1*fzhuan),25*(i-1),20);
}
//在认证码的上端画一条不规则的线
int visit[] = new int[6];
for (int i = 0; i < visit.length; i++) {
visit[i] = 1 + (int) (Math.random() * 10);
}
g.setColor(Color.BLACK);
int drawHigh[] = new int[6];
int drawwidth[] = new int[6];
//折点坐标
for (int i = 0; i < 6; i++) {
drawHigh[i] = 40 - (int) (Math.ceil(visit[i] * 3.8));
drawwidth[i] = 5 + i * 17;
}
g.setStroke(new BasicStroke(3.0f)); //折线粗细
g.setPaint(Color.gray);//折线的颜色
g.drawPolyline(drawwidth, drawHigh, 6); //画折线
// 将认证码存入Session
HttpSession session = request.getSession(true);
String time=String.valueOf(System.currentTimeMillis());
String value=time + "_" + sRand;
session.setAttribute("", time);
session.setAttribute("",value);
// 图象生效
g.dispose();
try {
ImageIO.write(image, "JPEG", response.getOutputStream()); // 输出图象到页面
} catch(IOException e) {
e.printStackTrace();
}
}
private static int getRandomIntColor() {
int[] rgb = getRandomRgb();
int color = 0;
for (int c : rgb) {
color = color << 8;
color = color | c;
}
return color;
}
private static int[] getRandomRgb() {
int[] rgb = new int[3];
Random random = new Random();
for (int i = 0; i < 3; i++) {
rgb[i] = random.nextInt(255);
}
return rgb;
}
}
