生成验证码JSP【复用代码】

该JSP可以生成验证码。以后用到的时候就方便了。

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ page contentType="image/jpeg"  import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
    public Color getColor(){
        Random random = new Random();
        int r = random.nextInt(256);//0-255
        int g = random.nextInt(256);
        int b = random.nextInt(256);
        return new Color(r,g,b);
    }
    public String getNum(){
        String str = "";
        Random random = new Random();
        for(int i=0;i<4;i++){
            str += random.nextInt(10);//0-9
        }
        return str;
    }
%>
<%
    response.setHeader("pragma", "mo-cache");
    response.setHeader("cache-control", "no-cache");
    response.setDateHeader("expires", 0);

    BufferedImage image = new BufferedImage(80,30,BufferedImage.TYPE_INT_RGB);

    Graphics g = image.getGraphics();
    g.setColor(new Color(200,200,200));
    g.fillRect(0,0,80,30);

    for (int i = 0; i < 30; i++) {
        Random random = new Random();
        int x = random.nextInt(80);
        int y = random.nextInt(30);
        int xl = random.nextInt(x+10);
        int yl = random.nextInt(y+10);
        g.setColor(getColor());
        g.drawLine(x, y, x + xl, y + yl);
    }

    g.setFont(new Font("serif", Font.BOLD,16));
    g.setColor(Color.BLACK);
    String checkNum = getNum();//"2525"

    StringBuffer sb = new StringBuffer();
    for(int i=0;i<checkNum.length();i++){
        sb.append(checkNum.charAt(i)+" ");//"2 5 2 5"
    }
    g.drawString(sb.toString(),15,20);

    session.setAttribute("CHECKNUM",checkNum);//2525

    ImageIO.write(image,"jpeg",response.getOutputStream());
    out.clear();
    out = pageContext.pushBody();
%>