JAVA生成问答式验证码图片，支持加减算法

原文：http://liuguihua0823.iteye.com/blog/1511355

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.servlet.http.HttpServletRequest;

import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.InterceptorRefs;
import org.apache.struts2.convention.annotation.ParentPackage;

import com.rd.p2p.additional.redisCaptcha.util.ResponseUtil;

@ParentPackage("p2p-api")
@InterceptorRefs({ @org.apache.struts2.convention.annotation.InterceptorRef("commonCheck") })
public class TestAction extends AppBaseAction {

    @Action("/app/test2")
    public void test() throws IOException{
        try {
            int width = 140, height = 37;
            String baseStr = generateCheckCode(request);  

            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            Graphics g = image.getGraphics();  

            Random random = new Random();  

            g.setColor(getRandColor(random, 200, 250));
            g.fillRect(0, 0, width, height);  

            String[] fontTypes = { "\u5b8b\u4f53", "\u65b0\u5b8b\u4f53", "\u9ed1\u4f53", "\u6977\u4f53", "\u96b6\u4e66" };
            int fontTypesLength = fontTypes.length;  

            g.setColor(getRandColor(random, 160, 200));
            g.setFont(new Font("Times New Roman", Font.PLAIN, 14 + random.nextInt(6)));  

            for (int i = 0; i < 255; 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);
            }  

            String [] baseChar = baseStr.split(" ");
            for (int i = 0; i < baseChar.length; i++) {
                g.setColor(getRandColor(random, 30, 150));
                g.setFont(new Font(fontTypes[random.nextInt(fontTypesLength)], Font.BOLD, 22 + random.nextInt(6)));
                g.drawString(baseChar[i], 24 * i + 10, 24);
            }  

            g.dispose();  

            //发送图片
            ResponseUtil.sendImg(response, image, "image/jpeg", "code", "jpg");
        } catch (IllegalStateException e) {
            System.out.println(e.getMessage());
            e.printStackTrace();
        }  

    }

    private static Color getRandColor(Random random, int fc, int bc){
        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);
    }  

    private static String generateCheckCode(HttpServletRequest request) {
        Random random = new Random();
        int intTemp;
        int intFirst = random.nextInt(100);
        int intSec = random.nextInt(100);
        String checkCode = "";
        int result = 0;
        switch (random.nextInt(6)) {
            case 0:
                if (intFirst < intSec) {
                    intTemp = intFirst;
                    intFirst = intSec;
                    intSec = intTemp;
                }
                checkCode = intFirst + " - " + intSec + " = ?";
                result = intFirst-intSec;
                break;
            case 1:
                if (intFirst < intSec) {
                    intTemp = intFirst;
                    intFirst = intSec;
                    intSec = intTemp;
                }
                checkCode = intFirst + " - ? = "+(intFirst-intSec);
                result = intSec;
                break;
            case 2:
                if (intFirst < intSec) {
                    intTemp = intFirst;
                    intFirst = intSec;
                    intSec = intTemp;
                }
                checkCode = "? - "+intSec+" = "+(intFirst-intSec);
                result = intFirst;
                break;
            case 3:
                checkCode = intFirst + " + " + intSec + " = ?";
                result = intFirst + intSec;
                break;
            case 4:
                checkCode = intFirst + " + ? ="+(intFirst+intSec);
                result = intSec;
                break;
            case 5:
                checkCode = "? + " + intSec + " ="+(intFirst+intSec);
                result = intFirst;
                break;
        }
        System.out.println("result=" + result);
        request.getSession().setAttribute("VERIFY_CODE", result);
        return checkCode;
    }  

}