java jsp实现登录验证码

工作中使用的java jsp实现的登录验证码。代码记录如下：

1.登录主页面(login.jsp)

pageEncoding="UTF-8"%>

登录

function refresh() {

//IE存在缓存,需要new Date()实现更换路径的作用

document.getElementById("image").src="../login/image.jsp?"+new Date();

}

用户名：

密码：

验证码：

2. 验证码生成jsp(image.jsp)

pageEncoding="UTF-8"%>

//获取随机颜色

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);

}

%>

//设置页面不缓存

response.setHeader("Pragma", "No-cache");

response.setHeader("Cache-Control", "no-cache");

response.setDateHeader("Expires", 0);

//在内存中创建图像

int width = 60;

int height = 20;

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

//获取图形上下文

Graphics g = image.getGraphics();

//随机类

Random random = new Random();

//设定背景

g.setColor(getRandColor(200, 250));

g.fillRect(0, 0, width, height);

//设定字体

g.setFont(new Font("Times New Roman",Font.PLAIN,18));

//随机产生干扰线

g.setColor(getRandColor(160, 200));

for (int i = 0; i < 100; 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);

}

//随机产生4位验证码

String[] codes = {"2","3","4","5","6","7","8","9","A","B","C","D","E","F","G","H","J","K","L","M","N","P","Q","R","S","T","U","V","W","X","Y","Z"};

String code = "";

for(int i=0;i<4;i++){

String str = codes[random.nextInt(codes.length)];

code += str;

// 将认证码显示到图象中

g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));

//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成

g.drawString(str, 13 * i + 6, 16);

}

// 将认证码存入SESSION

session.setAttribute("code", code);

// 图象生效

g.dispose();

// 输出图象到页面

ImageIO.write(image, "JPEG", response.getOutputStream());

//加上下面代码,运行时才不会出现java.lang.IllegalStateException: getOutputStream() has already been called ..........等异常

response.getOutputStream().flush();

response.getOutputStream().close();

response.flushBuffer();

out.clear();

out = pageContext.pushBody();

%>

3. 验证码检查页面(check.jsp：检查验证码是否输入正确)

pageEncoding="UTF-8"%>

验证

function same(){

loginForm.action = "login/login_login";

loginForm.submit();

}

function different(){

alert("请输入正确的验证码");

location.href = "login.jsp";

}

String userName = request.getParameter("userName");

String password = request.getParameter("userPwd");

%>

name="user.userName">

name="user.userPwd">

String rand = session.getAttribute("code").toString();

String input = request.getParameter("code");

if(rand.equals(input)){

out.println("");

}else{

out.print("");

}

%>