javax异常： javax.imageio.IIOException: Can't create output stream解决方法
- 验证码工具类：
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package com.newcapec.utils;
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import com.sun.image.codec.jpeg.JPEGCodec;
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import com.sun.image.codec.jpeg.JPEGImageEncoder;
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import java.awt.*;
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import java.awt.image.BufferedImage;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.util.Random;
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/**
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* Title: ValidateCode.java
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* Description: 验证码工具类
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*/
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public class ValidateCode {
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// 图片的宽度。
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private int width = 120;
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// 图片的高度。
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private int height = 40;
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// 验证码字符个数
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private int codeCount = 4;
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// 验证码干扰线数
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private int lineCount = 30;
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// 验证码
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private String code = null;
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// 验证码图片Buffer
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private BufferedImage buffImg = null;
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private char[] codeSequence = { 'A','a', 'B','b', 'C','c', 'D','d', 'E','e', 'F','f', 'g','H','h',
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'J','j', 'K','k','L', 'M','m', 'N','n', 'P','p', 'Q','q', 'R','r', 'S','s', 'T', 'U','u', 'V', 'W','w',
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'X','x', 'Y', 'Z', '2', '3', '4', '5', '6', '7', '8', '9'};
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// 生成随机数
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private Random random = new Random();
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public ValidateCode() {
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this.createCode();
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}
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/**
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*
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* @param width
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* 图片宽
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* @param height
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* 图片高
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*/
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public ValidateCode(int width, int height) {
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this.width = width;
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this.height = height;
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this.createCode();
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}
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/**
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*
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* @param width
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* 图片宽
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* @param height
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* 图片高
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* @param codeCount
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* 字符个数
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* @param lineCount
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* 干扰线条数
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*/
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public ValidateCode(int width, int height, int codeCount, int lineCount) {
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this.width = width;
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this.height = height;
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this.codeCount = codeCount;
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this.lineCount = lineCount;
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this.createCode();
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}
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public void createCode() {
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Random heightRandom = new Random();
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int codeX = 0;
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int fontHeight = 0;
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fontHeight = height-heightRandom.nextInt(7)-7;// 字体的高度
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codeX = width / (codeCount+1);// 每个字符的宽度
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// 图像buffer
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buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
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Graphics2D g = buffImg.createGraphics();
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// 将图像填充为白色
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g.setColor(Color.WHITE);
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g.fillRect(0, 0, width, height);
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// 创建字体
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ImgFontByte imgFont = new ImgFontByte();
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Font font = imgFont.getFont(fontHeight);
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g.setFont(font);
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// 绘制干扰线
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for (int i = 0; i < lineCount; i++) {
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int xs = getRandomNumber(width);
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int ys = getRandomNumber(height);
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int xe = xs + getRandomNumber(width / 8);
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int ye = ys + getRandomNumber(height / 8);
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g.setColor(getRandomColor());
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g.drawLine(xs, ys, xe, ye);
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}
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StringBuffer randomCode = new StringBuffer();
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// int x = 5;
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// 随机产生验证码字符
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for (int i = 0; i < codeCount; i++) {
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int h = height-8;
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int w = (i + 1) * codeX+heightRandom.nextInt(4);
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String strRand = String.valueOf(codeSequence[random
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.nextInt(codeSequence.length)]);
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// 设置字体颜色
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g.setColor(getRandomColor());
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int degree = new Random().nextInt() % 10;
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g.rotate(degree * Math.PI / 180,(w+codeX-5)/2, (h+fontHeight)/2);
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// 设置字体位置
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g.drawString(strRand, w, h ); //getRandomNumber(height / 2) + 25
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g.rotate(-degree * Math.PI / 150, (w+codeX-5)/2, (h+fontHeight)/2);
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randomCode.append(strRand);
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}
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code = randomCode.toString();
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}
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/** 获取随机颜色 */
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private Color getRandomColor() {
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int r = getRandomNumber(225);
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int g = getRandomNumber(225);
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int b = getRandomNumber(225);
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return new Color(r, g, b);
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}
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/** 获取随机数 */
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private int getRandomNumber(int number) {
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return random.nextInt(number);
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}
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public void write(String path) throws IOException {
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OutputStream sos = new FileOutputStream(path);
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this.write(sos);
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}
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public void write(OutputStream sos) throws IOException {
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// ImageIO.write(buffImg, "png", sos);
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JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(sos);
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encoder.encode(buffImg);
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sos.close();
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}
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public BufferedImage getBuffImg() {
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return buffImg;
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}
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public String getCode() {
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return code;
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}
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/** 字体样式类 */
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class ImgFontByte {
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public Font getFont(int fontHeight) {
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return new Font("Arial", Font.PLAIN, fontHeight);
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}
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}
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}
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- 使用
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public void scaptcha(){
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HttpServletResponse response = ServletActionContext.getResponse();
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response.reset();
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// 设置响应的类型格式为图片格式
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response.setContentType("image/jpeg");
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// 禁止图像缓存。
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response.setHeader("Pragma", "no-cache");
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response.setHeader("Cache-Control", "no-cache");
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response.setDateHeader("Expires", 0);
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ValidateCode instance = new ValidateCode();
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CookieUtil.setCookie(response, "scaptcha", instance.getCode().toUpperCase(), null, -1);
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try {
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instance.write(response.getOutputStream());
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
在使用ImageIO.write时，发现在Linux平台上，会出现异常：
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javax.imageio.IIOException: Can't create output stream
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检查tomcat的日志，终于真相大白：
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javax.imageio.IIOException: Can't create output stream!
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at javax.imageio.ImageIO.write(ImageIO.java:1521)
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Caused by: javax.imageio.IIOException: Can't create cache file!
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at javax.imageio.ImageIO.createImageOutputStream(ImageIO.java:395)
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at javax.imageio.ImageIO.write(ImageIO.java:1519)
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... 34 more
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Caused by: java.io.IOException: 系统找不到指定的路径。
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原来是ImageIO.write(image, "jpeg", response.getOutputStream());
查看日志，发现是由找不到文件引起
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Java.nio.file.NoSuchFileException: xxx.../temp/imageio4138671232726624650.tmp
- 主要原因如下：
在使用ImageIO进行图片写操作时，默认会使用缓存目录:${tomcat}/temp，在此缓存目录会生成缓存文件imageio4138671232726624650.tmp(这一串数字应该是当前时间戳，临时文件名)，有些生产环境的tomcat，会将temp目录删除，因此报错
- 4种解决方法如下：
- 在tomcat下新建temp目录;
- 与方法1相似，通过ImageIO.setCacheDirectory(cacheDirectory);设置任意的、存在的缓存目录
- ImageIO默认是使用缓存目录，可以通过ImageIO.setUseCache(false)来设置，更改缓存策略，不使用文件目录缓存，使用内存缓存
- 不使用ImageIO，换成其它JDK方法
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ImageIO.write(bi, "jpg", baos);
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换成：
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JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(response.getOutputStream());
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encoder.encode(image);