java登录验证码

package com.demo.vcode;

import java.io.InputStream;

public class VcodeObject {
	private String code;
	private InputStream in;

	public VcodeObject() {
	}

	public VcodeObject(String code, InputStream in) {
		this.code = code;
		this.in = in;
	}
//getters & setters
}

package com.demo.vcode;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Random;

import javax.imageio.ImageIO;

public class Vcode {
	public VcodeObject create() {
		// 生成随机验证码
		String code = this.generateRandomVerifyCode(4);
		// 生成附带验证码的图片
		BufferedImage img = this.generateImgWithCode(code, 80, 34);
		InputStream in = this.putImgInStream(img);
		return new VcodeObject(code, in);
	}

	/**
	 * 随机生成验证码
	 * 
	 * @param length
	 * @return String
	 */
	private String generateRandomVerifyCode(int length) {
		// 需要生成验证码的长度
		if (length <= 0 || length >= 8)
			length = 4;
		// 随机生成字符的范围
		String scope = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
		StringBuffer code = new StringBuffer();
		Random random = new Random();
		for (int i = 0; i < length; i++) {
			code.append(scope.charAt(random.nextInt(62)));
		}
		return code.toString();
	}

	/**
	 * 生成带有验证码的图片
	 * 
	 * @param code
	 * @param width
	 * @param height
	 * @return BufferedImage
	 */
	private BufferedImage generateImgWithCode(String code, int width, int height) {
		BufferedImage img = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		Graphics brush = img.getGraphics();
		// 设置背景和边框颜色
		brush.setColor(this.getColor());
		brush.fillRect(0, 0, width - 1, height - 1);
		brush.drawRect(0, 0, width - 1, height - 1);
		// 写入验证码
		brush.setColor(this.getColor());
		brush.setFont(new Font("Times New Roman", Font.ITALIC, 28));
		brush.drawString(code, 7, 22);
		// 绘制干扰线条
		// 图片画完，关闭资源
		brush.dispose();
		return img;
	}

	/**
	 * 获取随机颜色
	 * 
	 * @return Color
	 */
	private Color getColor() {
		Random random = new Random();
		int r = random.nextInt(255);
		int g = random.nextInt(255);
		int b = random.nextInt(255);
		return new Color(r, g, b);
	}

	/**
	 * 将图片放入输入流中
	 * 
	 * @param image
	 * @return InputStream
	 */
	private InputStream putImgInStream(BufferedImage image) {
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		try {
			ImageIO.write(image, "JPEG", out);
		} catch (IOException e) {
			e.printStackTrace();
		}
		InputStream in = new ByteArrayInputStream(out.toByteArray());
		return in;
	}
}

package com.demo.vcode;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DemoServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void init(ServletConfig config) throws ServletException {
	}

	public void doGet(HttpServletRequest req, HttpServletResponse res)
			throws IOException, ServletException {
		res.setContentType("image/png");
		Vcode vcode = new Vcode();
		VcodeObject vcodeObject = vcode.create();
		InputStream in = vcodeObject.getIn();
		req.getSession().setAttribute("vcode", vcodeObject.getCode());
		
		byte[] bytes = new byte[1024];
		int length = 0;
		try {
			OutputStream out = res.getOutputStream();
			while ((length = in.read(bytes)) != -1) {
				out.write(bytes, 0, length);
			}
			in.close();
			out.flush();
		} catch (Exception e) {

		}
	}

	public void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws IOException, ServletException {
	}

	public void destroy() {
	}
}

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

	<servlet>
		<servlet-name>vcode</servlet-name>
		<servlet-class>com.demo.vcode.DemoServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>vcode</servlet-name>
		<url-pattern>/vcode</url-pattern>
	</servlet-mapping>
</web-app>

http://127.0.0.1:8080/vcode/vcode