最简单的验证码（利用JSP生成验证码）

忘是亡心i 2022-07-17 03:27 152阅读 0赞

可以直接利用jsp输出验证码。jsp文件如下：

<%@ page contentType="image/jpeg"
    	import="java.awt.*,
    java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="utf-8"%>
    <%!
    Color getRandColor(int fc,int bc)
    {
    Random random = new Random();
    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);
    }
    %>
    <%
    out.clear();//这句针对resin服务器，如果是tomacat可以不要这句
    response.setHeader("Pragma","No-cache");
    response.setHeader("Cache-Control","no-cache");
    response.setDateHeader("Expires", 0);
    int width=60, height=20;
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    Graphics g = image.getGraphics();
    Random random = new Random();
    g.setColor(getRandColor(200,250));
    g.fillRect(0, 0, width, height);
    g.setFont(new Font("Times New Roman",Font.PLAIN,18));
    g.setColor(getRandColor(160,200));
    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);
    }
    String sRand="";
    for (int i=0;i<4;i++){
    String rand=String.valueOf(random.nextInt(10));
    sRand+=rand;
    g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
    g.drawString(rand,13*i+6,16);
    }
    // 将认证码存入SESSION
    session.setAttribute("sRand",sRand);
    g.dispose();
    ImageIO.write(image, "JPEG", response.getOutputStream());
    %>

前台获取这个验证码代码如下：

<img οnclick="javascript:loadimage();" title="换一张试试" name="randImage" id="randImage" src="image.jsp

因为需要刷新验证码，所以还需要加点js代码。

function loadimage(){
    		document.getElementById("randImage").src = "image.jsp?"+Math.random();
    	}