驗證碼繪制

package com.oracle.mvc;



import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet("/validateCode")
public class ValidateCodeServelet extends HttpServlet{

    //驗證碼 GDI+技術  PHP NET JAVA 繪圖技術 點 線  面 圖檔
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //jsp-api jar包
        //jsp的九大内置對象
        //request response session application out Exception config page pageContext
        //作用域 pageContext request session application
        //servelt-api jar包
        //Servlet的5大對象
        //HttpServletRequest HttpServletResponse HttpSession ServletContext HttpCookie
        //request.getParamter("");  //擷取前台的參數
        //response.sendRedirect("");//重定向  不帶資料
        //req.getRequestDispatcher().forward();//轉發 //帶資料
        //req.getSession();
        HttpSession session=req.getSession();
        Random random=new Random();
        int width=100;
        int height=52;

        //1、準備好一張圖檔  矩形
        BufferedImage validateCodeIMG=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        //2、擷取圖檔的畫筆
        Graphics graphics = validateCodeIMG.getGraphics();
        graphics.setColor(Color.WHITE);
        //3、繪制矩形
        graphics.fillRect(0,0,width,height);
        //4、準備素材 0-9+A-Z+a-z
        String[] res = {"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","j","m","n","q","r","t","v","x","y","A","B","C","D","E","F","G","H","I","J","M","N","Q","R","T","X","Y","中","大","國","華","人","名","共","你","張","三"};
        Font font=new Font("微軟雅黑",Font.BOLD,25);
        graphics.setFont(font);

        //5、開始繪制4個 随機
        String data="";
        for (int i=0;i<4;i++){
            graphics.setColor(new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255)));
            int index = random.nextInt(res.length);
            String num=res[index];
            data+=num;
            graphics.drawString(num,i*20,30);
        }
        session.setAttribute("validateCode",data);

        //6、繪制幹擾線
        for (int i=0;i<10;i++){
            graphics.setColor(new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255)));
            int ox=random.nextInt(width);
            int oy=random.nextInt(height);
            int ox2=random.nextInt(width);
            int oy2=random.nextInt(height);
            graphics.drawLine(ox,oy,ox2,oy2);
        }

        //7、繪制幹擾點
        for (int i=0;i<10;i++){
            graphics.setColor(new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255)));
            int ox=random.nextInt(width);
            int oy=random.nextInt(height);
            graphics.fillOval(ox,oy,5,5);
        }

        //8、渲染到圖檔  圖檔格式 png jpeg
        ImageIO.write(validateCodeIMG,"jpeg",resp.getOutputStream());





    }
}