package cn.lijun.checkimg;

import java.awt.image.BufferedImage;

import java.io.BufferedReader;

import java.awt.Color;

import java.io.FileReader;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import java.util.Random;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.Graphics2D;

import javax.imageio.ImageIO;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

* 验证码生成程序

*/

public class CheckImgServlet extends HttpServlet {

// 集合中保存所有成语

private List<String> words = new ArrayList<String>();

@Override

public void init() throws ServletException {

// 初始化阶段，读取new_words.txt

// web工程中读取 文件，必须使用绝对磁盘路径

String path = getServletContext().getRealPath("/WEB-INF/lijun.txt");

try {

BufferedReader reader = new BufferedReader(new FileReader(path));

String line;

while ((line = reader.readLine()) != null) {

words.add(line);

}

reader.close();

} catch (IOException e) {

e.printStackTrace();

}

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// 禁止缓存

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

// response.setHeader("Pragma", "no-cache");

// response.setDateHeader("Expires", -1);

int width = 120;

int height = 30;

// 步骤一 绘制一张内存中图片

BufferedImage bufferedImage = new BufferedImage(width, height,

BufferedImage.TYPE_INT_RGB);

// 步骤二 图片绘制背景颜色 ---通过绘图对象

Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔

// 绘制任何图形之前 都必须指定一个颜色

graphics.setColor(getRandColor(200, 250));

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

// 步骤三 绘制边框

graphics.setColor(Color.WHITE);

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

// 步骤四 四个随机数字

Graphics2D graphics2d = (Graphics2D) graphics;

// 设置输出字体

graphics2d.setFont(new Font("宋体", Font.BOLD, 18));

Random random = new Random();// 生成随机数

int index = random.nextInt(words.size());

String word = words.get(index);// 获得成语

// 定义x坐标

int x = 10;

for (int i = 0; i < word.length(); i++) {

// 随机颜色

graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random

.nextInt(110), 20 + random.nextInt(110)));

// 旋转 -30 --- 30度

int jiaodu = random.nextInt(60) - 30;

// 换算弧度

double theta = jiaodu * Math.PI / 180;

// 获得字母数字

char c = word.charAt(i);

// 将c 输出到图片

graphics2d.rotate(theta, x, 20);

graphics2d.drawString(String.valueOf(c), x, 20);

graphics2d.rotate(-theta, x, 20);

x += 30;

}

// 将验证码内容保存session

request.getSession().setAttribute("checkcode_session", word);

// 步骤五 绘制干扰线

graphics.setColor(getRandColor(160, 200));

int x1;

int x2;

int y1;

int y2;

for (int i = 0; i < 30; i++) {

x1 = random.nextInt(width);

x2 = random.nextInt(12);

y1 = random.nextInt(height);

y2 = random.nextInt(12);

graphics.drawLine(x1, y1, x1 + x2, x2 + y2);

}

// 将上面图片输出到浏览器 ImageIO

graphics.dispose();// 释放资源

//将图片写到response.getOutputStream()中

ImageIO.write(bufferedImage, "jpg", response.getOutputStream());

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doGet(request, response);

}

/**

* 取其某一范围的color

*

* @param fc

* int 范围参数1

* @param bc

* int 范围参数2

* @return Color

*/

private Color getRandColor(int fc, int bc) {

// 取其随机颜色

Random random = new Random();

if (fc > 255) {

fc = 255;

}

if (bc > 255) {

bc = 255;

}

int r = fc + random.nextInt(bc - fc);

int g = fc + random.nextInt(bc - fc);

int b = fc + random.nextInt(bc - fc);

return new Color(r, g, b);

}

}