java生成输出验证码图片，并进行验证的代码。包含生成验证码，servlet输出验证码，验证验证码是否正确的代码。
此代码可以直接使用。
需要注意的是，调用验证码图片时，最好在url上加上时间戳参数，可避免刷新时由于缓存而不刷新验证码。
1.获取验证码图片，进行验证的 servlet代码
package org.houyong.test.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.houyong.test.common.RandomValidateCode;
public class ValidateCode extends HttpServlet {
/**
* Constructor of the object.
*/
public ValidateCode() {
super();
}
/**
* Destruction of the servlet.
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet.
*
* 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
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
/**
* The doPost method of the servlet.
*
* This method is called when a form has its tag value method equals to post.
*
* @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
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String action=request.getParameter("action");
try {
if(action.equals("getImgCode")){
response.setContentType("image/jpeg");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expire", 0);
RandomValidateCode randomValidateCode = new RandomValidateCode();
try {
randomValidateCode.getRandcode(request, response);
} catch (Exception e) {
e.printStackTrace();
}
}else if(action.equals("validateCode")){
PrintWriter out=null;
try {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
out = response.getWriter();
String inputCode=request.getParameter("inputCode");
HttpSession session = request.getSession();
String code=(String) session.getAttribute("RANDOMVALIDATECODEKEY");
String returnStr="";
if(inputCode.toUpperCase().equals(code.toUpperCase())){
returnStr="success";
}else{
returnStr="failure";
}
out.print(returnStr);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
out.flush();
out.close();
}
}else{
response.sendRedirect("index.jsp");
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
response.sendRedirect("index.jsp");
}
}
/**
* Initialization of the servlet.
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}2.生成随机验证码图片的java代码
package org.houyong.test.common;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/*生成验证码*/
public class RandomValidateCode {
public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
private Random random = new Random();
private String randString = "123456789ABCDEFGHIJKLMNPQRSTUVWXYZ";//随机产生的字符串
private int width = 80;//图片宽
private int height = 26;//图片高
private int lineSize = 20;//干扰线数量
private int stringNum = 4;//随机产生字符数量
/*
* 获得字体
*/
private Font getFont(){
return new Font("Fixedsys",Font.CENTER_BASELINE,18);
}
/*
* 获得颜色
*/
private Color getRandColor(int fc,int bc){
if(fc > 255)
fc = 255;
if(bc > 255)
bc = 255;
int r = fc + random.nextInt(bc-fc-16);
int g = fc + random.nextInt(bc-fc-14);
int b = fc + random.nextInt(bc-fc-18);
return new Color(r,g,b);
}
/**
* 生成随机图片
*/
public void getRandcode(HttpServletRequest request,
HttpServletResponse response) {
HttpSession session = request.getSession();
//BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();//产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));
g.setColor(getRandColor(110, 133));
//绘制干扰线
for(int i=0;i<=lineSize;i++){
drowLine(g);
}
//绘制随机字符
String randomString = "";
for(int i=1;i<=stringNum;i++){
randomString=drowString(g,randomString,i);
}
session.removeAttribute(RANDOMCODEKEY);
session.setAttribute(RANDOMCODEKEY, randomString);
//System.out.println(randomString);
g.dispose();
try {
ImageIO.write(image, "JPEG", response.getOutputStream());//将内存中的图片通过流动形式输出到客户端
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* 绘制字符串
*/
private String drowString(Graphics g,String randomString,int i){
g.setFont(getFont());
g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
randomString +=rand;
g.translate(random.nextInt(3), random.nextInt(3));
g.drawString(rand, 13*i, 16);
return randomString;
}
/*
* 绘制干扰线
*/
private void drowLine(Graphics g){
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(13);
int yl = random.nextInt(15);
g.drawLine(x, y, x+xl, y+yl);
}
/*
* 获取随机的字符
*/
public String getRandomString(int num){
return String.valueOf(randString.charAt(num));
}
}