JSP產生隨機證碼，並且局部重新整理驗證碼

最後更新：2018-12-05 來源：互聯網

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1.前台jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>管理員登陸</title>

function change(){

var o = document.getElementById("random");

var timenow = new Date().getTime();

o.src = "<%=path%>/server/ImageValidate?d=" + timenow;

}

</script>

</head>

<body>

<img width="80px" height="30px" id="random" src="<%=path %>/server/ImageValidate"/>

</body>

</html>

2.後台生存隨機碼的servlet

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.util.Random;

import javax.servlet.ServletException;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.sun.image.codec.jpeg.JPEGCodec;

import com.sun.image.codec.jpeg.JPEGImageEncoder;

@SuppressWarnings("serial")

public class ImageValidate extends HttpServlet {

public ImageValidate() {

super();

}

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

request.setCharacterEncoding("GBK");

response.setCharacterEncoding("GBK");

response.setContentType("image/jpeg");

response.addHeader("pragma","NO-cache");

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

response.addDateHeader("Expries",0);

int width=80, height=30;

response.setContentType("text/html; charset=GBK");

String chose="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

char temp;//儲存隨機產生的chose元素

Random rand=new Random();

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

Graphics g = image.getGraphics();

//以下填充背景顏色

g.setColor(Color.YELLOW);

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

//畫邊框

g.setColor(Color.BLACK);

Font font;

g.drawRect(0,0,width-1,height-1);

StringBuffer sRand = new StringBuffer();

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

temp=chose.charAt(rand.nextInt(chose.length()));

sRand.append(temp);

font=new Font("Arial",Font.PLAIN,15 + rand.nextInt(10));//字型

g.setFont(font);

g.setColor(new Color(rand.nextInt(255),0,rand.nextInt(255)));//驗證碼的顏色

g.drawString(String.valueOf(temp),15*i+5,20+rand.nextInt(10));//位置

}

request.getSession().setAttribute("randomNumber",sRand.toString());//儲存產生的驗證碼值

//設定字型顏色

g.dispose();

ServletOutputStream outStream = response.getOutputStream();

JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(outStream);

encoder.encode(image);

outStream.close();

}

public void init() throws ServletException {

}

3.xml設定檔<servlet> <servlet-name>ImageValidate</servlet-name> <servlet-class>user.ImageValidate</servlet-class> </servlet> <servlet-mapping> <servlet-name>ImageValidate</servlet-name> <url-pattern>/server/ImageValidate</url-pattern> </servlet-mapping>

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