用java怎么样生成登录验证码
用java怎么样生成登录验证码 --------------------编程问答-------------------- http://esffor.javaeye.com/blog/96467 --------------------编程问答-------------------- 网上有例子的，自己搜。 --------------------编程问答--------------------
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%@ page import="java.io.OutputStream" %>
<%!
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);
}
%>
<%
try{
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);
OutputStream os=response.getOutputStream();
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);
}
session.setAttribute("rand",sRand);
g.dispose();
ImageIO.write(image, "JPEG",os);
os.flush();
os.close();
os=null;
response.flushBuffer();
out.clear();
out = pageContext.pushBody();
}catch(IllegalStateException e){
System.out.println(e.getMessage());
e.printStackTrace();
}
%>
这是我现在用的，建个jsp文件贴进去。
<img border=0 src="image.jsp"> --------------------编程问答-------------------- 哈哈 ，这个其实 不难 --------------------编程问答-------------------- 给你个我用的servlet的
[code=Java]ublic class ValidationCode extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
//选择其中的字符作为验证码
private static String codeChars="%#123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
private static Color getRandomColor(int minColor,int maxColor){
Random random=new Random();
if(minColor>255)
minColor=255;
if(maxColor>255)
maxColor=255;
int red=minColor+random.nextInt(maxColor-minColor);
int green=minColor+random.nextInt(maxColor-minColor);
int blue=minColor+random.nextInt(maxColor-minColor);
return new Color(red,green,blue);
}
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
int charsLength=codeChars.length();
//关闭缓冲区
response.setHeader("ragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
int width=90,height=20;
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics g=image.getGraphics();
Random random=new Random();
g.setColor(getRandomColor(180,250));//背景
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.ITALIC,height));
g.setColor(getRandomColor(120,180));//字体
StringBuilder validationCode=new StringBuilder();
String[] fontNames={"Times New Roman","Book antique","Arial"};
for(int i=0;i<3+random.nextInt(3);i++){
g.setFont(new Font(fontNames[random.nextInt(3)],Font.ITALIC,height));
char codeChar=codeChars.charAt(random.nextInt(charsLength));
validationCode.append(codeChar);
g.setColor(getRandomColor(10,100));
g.drawString(String.valueOf(codeChar), 16*i+random.nextInt(7),height-random.nextInt(6) );
}
HttpSession session=request.getSession();
session.setMaxInactiveInterval(5*60);
session.setAttribute("validation_code", validationCode.toString());
g.dispose();//关闭graphic
OutputStream os=response.getOutputStream();
ImageIO.write(image, "JPEG", os);
}
}/code] --------------------编程问答-------------------- 其实就是用一个servlet生成一个图片 --------------------编程问答-------------------- 网上许多 --------------------编程问答-------------------- 都是牛人！哎！要加油！ --------------------编程问答-------------------- 楼上的基本可以解决问题了..我就不贴代码了..
我用的是一个servlet..生成图片! --------------------编程问答-------------------- 生成个图片，在随机生成一些数字或汉字加上去。想更模糊点在随机绘制一些线条在图片上
网上例子很多有的做的很美观 --------------------编程问答-------------------- 学习中... --------------------编程问答-------------------- 收藏了！！！！！！！！！！！！！！！！！！！！！ --------------------编程问答-------------------- 网上多的是，找去用 --------------------编程问答--------------------
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa--------------------编程问答-------------------- 验证码？网上一堆 http://esffor.javaeye.com/blog/96467 --------------------编程问答-------------------- fwegdfd --------------------编程问答-------------------- 网上下载一个，直接调用就可以了 --------------------编程问答-------------------- 可以用开源已经实现好的组件
jcaptcha --------------------编程问答-------------------- 这个不错，是apache的。楼主可以试试。哈 --------------------编程问答-------------------- 全是servlet --------------------编程问答-------------------- 用servlet处理
补充：Java , Java EE
