java web中图片验证码功能的简单实现方法

用户在注册网站信息的时候基本上都要数据验证码验证。那么图片验证码功能该如何实现呢？

大概步骤是：

1.在内存中创建缓存图片

2.设置背景色

3.画边框

4.写字母

5.绘制干扰信息

6.图片输出

废话不多说，直接上代码

package com.lsgjzhuwei.servlet.response;

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.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
* Servlet implementation class VerificationCode
*/
@WebServlet(asyncSupported = true, urlPatterns = { "/VerificationCode" })
public class VerificationCode extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
  * @see HttpServlet#HttpServlet()
  */
 public VerificationCode() {
   super();
   // TODO Auto-generated constructor stub
 }

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub

int width = 120;
int height = 30;

//创建一张内存中的缓存图片
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

///背景色
//通过graphics绘制图像
Graphics graphics = bufferedImage.getGraphics();
//设置颜色
graphics.setColor(Color.yellow);
//填充
graphics.fillRect(0, 0, width, height);

///画边框
graphics.setColor(Color.blue);
graphics.drawRect(0, 0, width-1, height-1);

//写字母
String content = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcedfghijklmnopqrstuvwxyz1234567890";
Random random = new Random();
//设置字体颜色
graphics.setColor(Color.red);
//设置字体及大小
graphics.setFont(new Font("宋体", Font.BOLD, 20));
int x=20;
int y=20;
for(int i = 0; i < 4; i++)
{
int index = random.nextInt(content.length());
char letter = content.charAt(index);
graphics.drawString(letter+" ", x, y);
x = x+20;
}

//绘制干扰线
int x1;
int x2;
int y1;
int y2;
graphics.setColor(Color.LIGHT_GRAY);
for(int i = 0;i <50;i++)
{
x1=random.nextInt(width);
x2=random.nextInt(width);
y1=random.nextInt(height);
y2=random.nextInt(height);
graphics.drawLine(x1, y1, x2, y2);
}

//将图片输出到浏览器
//将内存的图片通过浏览器输出流输出成jpg图片
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());

}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

}