登录验证码。。

html页面：

<form action="login" method="post">
用户名：<input type="text" name="username" id="username"/><br/>
密码：&nbsp;&nbsp;&nbsp;<input type="password" name="password" id="password"/><br/>
验证码：<input type="text" name="identifyCode" id="identifyCode"/>
<img src="identifyCode" id="identifyCodeImg" onclick="getCode();" title="换一张"/><br/>
<input type="button" value="登录" onclick="test();"/>
<span id="resultMsg" style="color: red;"></span>
</form>

js：

function test(){
$.ajax({
url:"login",
data:{
username:$("#username").val(),
password:$("#password").val(),
identifyCode:$("#identifyCode").val()
},
type:"POST",
dataType:"json",
success:function(data){
if(data.success){
window.location.href="user/operation";
}
else{
$("#resultMsg").html(data.message);
}

},
erro:function(){
alert("爆炸了！");
}

});
}
function getCode(){
$("#identifyCodeImg").attr("src","identifyCode?flag="+Math.random());
}

controller：

private Random random = new Random();
private String[] allCodes = {
"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
"A", "B", "C", "D", "E", "F", "G", "H", "I",
"J", "K", "L", "M", "N", "O", "P", "Q", "R",
"S", "T", "U", "V", "W", "X", "Y", "Z"
};

@RequestMapping(value="identifyCode")
public void getCode(HttpServletRequest request,HttpServletResponse response) throws IOException {
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "No-cache");
response.setDateHeader("Expires", 0);//禁止客户端缓存页面
response.setContentType("image/jpg");//设置响应正文类型为图片
int height = 20;
int width = 60;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();//获取处理图片的画笔
g.setColor(getRandomColor(200, 250));//设置背景色
g.fillRect(0, 0, width, height);//画一个矩形
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));//设置字体
g.setColor(getRandomColor(160, 200));//设置干扰线的颜色
for (int i = 0; i < 100; i++){//画一百条干扰线
int x = random.nextInt(width);
int y = random.nextInt(height);
int x1 = random.nextInt(10);
int y1 = random.nextInt(10);
g.drawLine(x, y, x1, y1);//干扰线的两个顶点坐标
}

String strCode = "";
for (int i = 0; i < 4; i++){//生成四个随机字符
String strNumber = allCodes[random.nextInt(36)];
strCode += strNumber;
g.setColor(getRandomColor(20, 120));
g.drawString(strNumber , 13 * i + 3, 16);
}
request.getSession(true).setAttribute("code", strCode);//将生成的验证码存入session
g.dispose();//释放图像的上下文资源
ImageIO.write(image, "JPEG", response.getOutputStream());//输出JPEG格式图像
response.getOutputStream().flush();//刷新输出流
response.getOutputStream().close();//关闭输出流
}

private Color getRandomColor(int min, int max){
int r = min + random.nextInt(max - min);
int b = min + random.nextInt(max - min);
int g = min + random.nextInt(max - min);
return new Color(r, b, g);
}

依照前人的来做的。。前几天写的。。忘了来源了。。。0.0.0