package com.newcapec.utils;

import com.sun.image.codec.jpeg.JPEGCodec;

import com.sun.image.codec.jpeg.JPEGImageEncoder;

import java.awt.*;

import java.awt.image.BufferedImage;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Random;

/** 

 * <p>Title: ValidateCode.java</p>  

 * <p>Description: 验证码工具类</p>  

 */

public class ValidateCode {    

    // 图片的宽度。  

    private int width = 120;  

    // 图片的高度。  

    private int height = 40;  

    // 验证码字符个数  

    private int codeCount = 4;  

    // 验证码干扰线数  

    private int lineCount = 30;  

    // 验证码  

    private String code = null;  

    // 验证码图片Buffer  

    private BufferedImage buffImg = null;  

    private char[] codeSequence = { 'A','a', 'B','b', 'C','c', 'D','d', 'E','e', 'F','f', 'g','H','h',  

            'J','j', 'K','k','L', 'M','m', 'N','n', 'P','p', 'Q','q', 'R','r', 'S','s', 'T', 'U','u', 'V', 'W','w',  

            'X','x', 'Y', 'Z', '2', '3', '4', '5', '6', '7', '8', '9'};  

    // 生成随机数  

    private Random random = new Random();  

    public ValidateCode() {  

        this.createCode();  

    }  

    /** 

     *  

     * @param width 

     *            图片宽 

     * @param height 

     *            图片高 

     */  

    public ValidateCode(int width, int height) {  

        this.width = width;  

        this.height = height;  

        this.createCode();  

    }  

    /** 

     *  

     * @param width 

     *            图片宽 

     * @param height 

     *            图片高 

     * @param codeCount 

     *            字符个数 

     * @param lineCount 

     *            干扰线条数 

     */  

    public ValidateCode(int width, int height, int codeCount, int lineCount) {  

        this.width = width;  

        this.height = height;  

        this.codeCount = codeCount;  

        this.lineCount = lineCount;  

        this.createCode();  

    }  

    public void createCode() {  

        Random heightRandom = new Random();

        int codeX = 0;  

        int fontHeight = 0;  

        fontHeight = height-heightRandom.nextInt(7)-7;// 字体的高度  

        codeX = width / (codeCount+1);// 每个字符的宽度  

        // 图像buffer  

        buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);  

        Graphics2D g = buffImg.createGraphics();  

        // 将图像填充为白色  

        g.setColor(Color.WHITE);  

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

        // 创建字体  

        ImgFontByte imgFont = new ImgFontByte();  

        Font font = imgFont.getFont(fontHeight);  

        g.setFont(font);  

        // 绘制干扰线  

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

            int xs = getRandomNumber(width);  

            int ys = getRandomNumber(height);  

            int xe = xs + getRandomNumber(width / 8);  

            int ye = ys + getRandomNumber(height / 8);  

            g.setColor(getRandomColor());  

            g.drawLine(xs, ys, xe, ye);  

        }  

        StringBuffer randomCode = new StringBuffer();  

//        int x = 5;

        // 随机产生验证码字符  

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

            int h = height-8;

            int w = (i + 1) * codeX+heightRandom.nextInt(4);

            String strRand = String.valueOf(codeSequence[random  

                    .nextInt(codeSequence.length)]);  

            // 设置字体颜色  

            g.setColor(getRandomColor());  

            int degree = new Random().nextInt() % 10;

            g.rotate(degree * Math.PI / 180,(w+codeX-5)/2, (h+fontHeight)/2);

            // 设置字体位置  

            g.drawString(strRand, w, h );  //getRandomNumber(height / 2) + 25

            g.rotate(-degree * Math.PI / 150, (w+codeX-5)/2, (h+fontHeight)/2);

            randomCode.append(strRand);  

        }  

        code = randomCode.toString();  

    }  

    /** 获取随机颜色 */  

    private Color getRandomColor() {  

        int r = getRandomNumber(225);  

        int g = getRandomNumber(225);  

        int b = getRandomNumber(225);  

        return new Color(r, g, b);  

    }

    /** 获取随机数 */  

    private int getRandomNumber(int number) {  

        return random.nextInt(number);  

    }  

    public void write(String path) throws IOException {  

        OutputStream sos = new FileOutputStream(path);  

        this.write(sos);  

    }  

    public void write(OutputStream sos) throws IOException {  

//         ImageIO.write(buffImg, "png", sos);

        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(sos);

        encoder.encode(buffImg);

        sos.close();  

    }  

    public BufferedImage getBuffImg() {  

        return buffImg;  

    }  

    public String getCode() {  

        return code;  

    }  

    /** 字体样式类 */  

    class ImgFontByte {

        public Font getFont(int fontHeight) {  

            return new Font("Arial", Font.PLAIN, fontHeight);

        }  

    }  

}

检查tomcat的日志，终于真相大白：

javax.imageio.IIOException: Can't create output stream!

 at javax.imageio.ImageIO.write(ImageIO.java:1521)

Caused by: javax.imageio.IIOException: Can't create cache file!

 at javax.imageio.ImageIO.createImageOutputStream(ImageIO.java:395)

 at javax.imageio.ImageIO.write(ImageIO.java:1519)

 ... 34 more

Caused by: java.io.IOException: 系统找不到指定的路径。

原来是ImageIO.write(image, "jpeg", response.getOutputStream());