待解决：验证码不显示

最新推荐文章于 2025-01-20 14:41:24 发布

转载最新推荐文章于 2025-01-20 14:41:24 发布 · 1.4k 阅读

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看别人的程序，却没有别人的结果

AuthCode.java

package aa.dd;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Font;
import java.awt.image.BufferedImage;
import java.util.Random;

public class AuthCode {
public static final int AUTHCODE_LENGTH = 5; // 验证码长度
public static final int SINGLECODE_WIDTH = 15; // 单个验证码宽度
public static final int SINGLECODE_HEIGHT = 30; // 单个验证码高度
public static final int SINGLECODE_GAP = 4; // 单个验证码之间间隔
public static final int IMG_WIDTH = AUTHCODE_LENGTH * (SINGLECODE_WIDTH + SINGLECODE_GAP);
public static final int IMG_HEIGHT = SINGLECODE_HEIGHT;
public static final char[] CHARS = {'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',
'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' };
static Random random = new Random();

/**
* 返回图片中的数字
* @return String
*/
public static String getAuthCode() {
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < 5; i++) {// 生成6个字符
buffer.append(CHARS[random.nextInt(CHARS.length)]);
}
return buffer.toString();
}

/**
* 返回带数字的图片
* @return BufferedImage
*/
public static BufferedImage getAuthImg(String authCode) {
// 设置图片的高、宽、类型
// RGB编码：red、green、blue
BufferedImage img = new BufferedImage(IMG_WIDTH, IMG_HEIGHT,
BufferedImage.TYPE_INT_BGR);
// 得到图片上的一个画笔
Graphics g = img.getGraphics();
// 设置画笔的颜色，用来做背景色
g.setColor(Color.RED);
// 用画笔来填充一个矩形，矩形的左上角坐标，宽，高
g.fillRect(0, 0, IMG_WIDTH, IMG_HEIGHT);
// 将画笔颜色设置为黑色，用来写字
g.setColor(Color.BLACK);
// 设置字体：宋体、不带格式的、字号
g.setFont(new Font("宋体", Font.PLAIN, SINGLECODE_HEIGHT + 5));
// 输出数字
char c;
for (int i = 0; i < authCode.toCharArray().length; i++) {
// 取到对应位置的字符
c = authCode.charAt(i);
// 画出一个字符串：要画的内容，开始的位置，高度
g.drawString(c + "", i * (SINGLECODE_WIDTH + SINGLECODE_GAP)
+ SINGLECODE_GAP / 2, IMG_HEIGHT);
}
Random random = new Random();
// 干扰素
for (int i = 0; i < 15; i++) {
int x = random.nextInt(IMG_WIDTH);
int y = random.nextInt(IMG_HEIGHT);
int x2 = random.nextInt(IMG_WIDTH);
int y2 = random.nextInt(IMG_HEIGHT);
g.drawLine(x, y, x + x2, y + y2);
}
return img;
}
}

getAuthCodeServlet.java

package aa.dd;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 得到生成验证码图片的servlet
* @author 林炳文Evankaka（博客：http://blog.youkuaiyun.com/evankaka）
* @since 2015.6.22
*/
public class getAuthCodeServlet extends HttpServlet {

/**
*
*/
private static final long serialVersionUID = 56859;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

String authCode = AuthCode.getAuthCode();

request.getSession().setAttribute("authCode", authCode); //将验证码保存到session中，便于以后验证

try {
//发送图片
ImageIO.write(AuthCode.getAuthImg(authCode), "JPEG", response.getOutputStream());
} catch (IOException e){
e.printStackTrace();
}

}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}

}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

<servlet>
<servlet-name>getAuthCodeServlet</servlet-name>
<servlet-class>aa.dd.getAuthCodeServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>getAuthCodeServlet</servlet-name>
<url-pattern>/servlet/getAuthCodeServlet</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
</web-app>

index.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>
<base href="<%=basePath%>">

<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

</head>

<body>
<form action="index.jsp" method="post">
<img src="servlet/getAuthCodeServlet" id="authImg"/>
<a href="#" onClick="window.location.reload()">看不清</a><br>
<input type="text" name="inputCode">
<%
String inputCode = (String)request.getParameter("inputCode");
String authCode = (String)session.getAttribute("authCode");
if(inputCode!=null){
if(authCode.equalsIgnoreCase(inputCode)){
out.print("验证码正确！");
}else{
out.print("验证码错误！请重新输入！");
}
}
%>
<br>
<input type="submit" value="提交">
</form>
</body>
</html>