驗證碼圖片生成工具類——Captcha.java

 

驗證碼圖片生成工具，使用JAVA生成的圖片驗證碼，調用getRandcode方法獲取圖片驗證碼，以流的方式傳輸到前端頁面。

 

源碼如下：(點擊下載  Captcha.java)

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 驗證碼圖片生成工具
 *  使用JAVA生成的圖片驗證碼，調用getRandcode方法獲取圖片驗證碼，以流的方式傳輸到前端頁面。
 *  
 * 
 * 作者: zhoubang 
 * 日期：2015年8月7日 上午10:41:05
 */
public class Captcha {

    public static final String RANDOMCODEKEY = "sess_captcha";// 放到session中的key
    private Random random = new Random();
    private String randString = "0123456789";// 隨機產生的字符串

    private int width = 80;// 圖片寬
    private int height = 26;// 圖片高
    private int lineSize = 40;// 干擾線數量
    private int stringNum = 4;// 隨機產生字符數量

    /*
     * 獲得字體
     */
    private Font getFont() {
        return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
    }

    /*
     * 獲得顏色
     */
    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);
    }

    /*
     * 繪制字符串
     */
    private String drowString(Graphics g, String randomString, int i) {
        g.setFont(getFont());
        g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));
        String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
        randomString += rand;
        g.translate(random.nextInt(3), random.nextInt(3));
        g.drawString(rand, 13 * i, 16);
        return randomString;
    }

    /*
     * 繪制干擾線
     */
    private void drowLine(Graphics g) {
        int x = random.nextInt(width);
        int y = random.nextInt(height);
        int xl = random.nextInt(13);
        int yl = random.nextInt(15);
        g.drawLine(x, y, x + xl, y + yl);
    }

    /*
     * 獲取隨機的字符
     */
    public String getRandomString(int num) {
        return String.valueOf(randString.charAt(num));
    }
    
    
    /**
     * 生成隨機圖片
     */
    public void getRandcode(HttpServletRequest request, HttpServletResponse response) {
        HttpSession session = request.getSession();
        // BufferedImage類是具有緩沖區的Image類,Image類是用於描述圖像信息的類
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
        Graphics g = image.getGraphics();// 產生Image對象的Graphics對象,改對象可以在圖像上進行各種繪制操作
        g.fillRect(0, 0, width, height);
        g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
        g.setColor(getRandColor(110, 133));
        // 繪制干擾線
        for (int i = 0; i <= lineSize; i++) {
            drowLine(g);
        }
        // 繪制隨機字符
        String randomString = "";
        for (int i = 1; i <= stringNum; i++) {
            randomString = drowString(g, randomString, i);
        }
        session.removeAttribute(RANDOMCODEKEY);
        session.setAttribute(RANDOMCODEKEY, randomString);
        g.dispose();
        try {
            ImageIO.write(image, "JPEG", response.getOutputStream());// 將內存中的圖片通過流動形式輸出到客戶端
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

簡單使用方法（可自行設計，此方法為servlet調用）：

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(description = "圖片驗證碼生成", urlPatterns = { "/ImageServlet" })
public class ImageServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ImageServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("image/jpeg");// 設置相應類型,告訴瀏覽器輸出的內容為圖片
        response.setHeader("Pragma", "No-cache");// 設置響應頭信息，告訴瀏覽器不要緩存此內容
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expire", 0);
        Captcha randomValidateCode = new Captcha();
        try {
            randomValidateCode.getRandcode(request, response);// 輸出圖片方法
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}