Java IO操作的工具类总结

/**   *  ClassName: IOHelper.java   *  Created on 2013   *  Copyrights 2013 hi.csdn.net/tjcyjd All rights reserved.   *  site: http://hi.csdn.net/tjcyjd   *  email: 908599713@qq.com   */  package com.kinder.common;    import java.awt.image.BufferedImage;  import java.io.BufferedInputStream;  import java.io.BufferedOutputStream;  import java.io.File;  import java.io.FileInputStream;  import java.io.FileOutputStream;  import java.io.IOException;  import java.io.InputStream;  import java.io.OutputStream;  import java.text.SimpleDateFormat;  import java.util.Date;    import org.slf4j.Logger;  import org.slf4j.LoggerFactory;    import com.sun.image.codec.jpeg.ImageFormatException;  import com.sun.image.codec.jpeg.JPEGCodec;  import com.sun.image.codec.jpeg.JPEGImageEncoder;    /**   * IO操作的工具类   *    * @author yjd   */  public class IOHelper {   private static Logger logger = LoggerFactory.getLogger(IOHelper.class);     private IOHelper() {   }     /**    * 根据指定的文件名从classpath下把该文件加载成InputStream实例    *     * @param path    * @return    */   public static InputStream getInputStreamFromClassPath(String path) {    return Thread.currentThread().getContextClassLoader()      .getResourceAsStream(path);   }     /**    * 创建目录    *     * @param dirFile    * @return    * @throws RuntimeException    */   public static boolean createDir(File dirFile) throws RuntimeException {    boolean flag = false;    if (dirFile.exists()) {     flag = true;    } else {     flag = dirFile.mkdirs();    }    return flag;   }     /**    * 删除目录    *     * @param dirFile    * @return    * @throws RuntimeException    */   public static boolean deleteDir(File dirFile) throws RuntimeException {    boolean flag = false;    if (!dirFile.exists()) {     flag = true;    } else {     if (deleteSubFiles(dirFile)) {      flag = dirFile.delete();     }    }    return flag;   }     /**    * 清空指定目录下的所有文件    *     * @param dir    */   public static boolean deleteSubFiles(File dir) {    logger.debug("开始清除{}下的所有文件", dir.getAbsolutePath());    boolean flag = false;    if (dir.exists() && dir.isDirectory()) {     File[] subs = dir.listFiles();     int succ = 0;     int fail = 0;     int length = subs == null ? 0 : subs.length;     File sub = null;     try {      for (int i = 0; i < length; i++) {       sub = subs[i];       if (sub.delete()) {        succ++;       } else {        fail++;       }      }      flag = true;     } catch (Exception e) {      logger.error("清除{}下的" + sub.getAbsolutePath() + "文件失败，原因是：{}",        dir.getAbsolutePath(), e);     }     logger.debug("清除{}下的所有文件, 成功{}个", dir.getAbsolutePath(), succ);     logger.debug("清除{}下的所有文件, 失败{}个", dir.getAbsolutePath(), fail);    }    return flag;   }     /**    * 获取指定文件的扩展名    *     * @param fileName    * @return    */   public static String getExtend(String fileName) {    return fileName.substring(fileName.lastIndexOf('.'));   }     /**    * 使用当前日期时间来产生"yyyyMMddHHmmssSSS"的字符串，主要用来做文件名    *     * @return    */   public static String generateFileNameByDateTime() {    return new SimpleDateFormat("yyyyMMddHHmmssSSS").format(new Date());   }     /**    * 把源文件的内容复制到目标文件    *     * @param src    *            源文件    * @param dest    *            目标文件    */   public static void copy(File src, File dest) throws IOException {    BufferedInputStream bis = null;    BufferedOutputStream bos = null;    byte[] b = new byte[8192];    try {     bis = new BufferedInputStream(new FileInputStream(src));     bos = new BufferedOutputStream(new FileOutputStream(dest));       for (int count = -1; (count = bis.read(b)) != -1;) {      bos.write(b, 0, count);     }     bos.flush();    } catch (IOException e) {     throw e;    } finally {     close(bis);     close(bos);    }   }     /**    * 把源图片srcImg缩小至指定的宽度和高度并存放至dest目标文件    *     * @param srcImg    * @param dest    * @param outWidth    * @param outHeight    */   public static void resizeToFile(BufferedImage srcImg, File dest,     int outWidth, int outHeight) throws RuntimeException {    BufferedImage pbFinalOut = null;    if (srcImg.getWidth() == outWidth && srcImg.getHeight() == outHeight) {     pbFinalOut = srcImg;    } else {     pbFinalOut = IOHelper.scaleImage(srcImg, outWidth, outHeight);    }    FileOutputStream out = null;    try {     out = new FileOutputStream(dest);     JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);     encoder.encode(pbFinalOut);    } catch (ImageFormatException e) {     throw new RuntimeException(e);    } catch (IOException e) {     throw new RuntimeException(e);    } finally {     close(out);    }   }     /**    * 把源图像缩小成指定宽高    *     * @param srcImg    *            源图片    * @param outWidth    *            宽    * @param outHeight    *            高    * @return 压缩后的图像对象    */   public static BufferedImage scaleImage(BufferedImage srcImg, int outWidth,     int outHeight) {    int width = srcImg.getWidth();    int height = srcImg.getHeight();    int[] rgbArray = srcImg.getRGB(0, 0, width, height, null, 0, width);    BufferedImage pbFinalOut = new BufferedImage(outWidth, outHeight,      BufferedImage.TYPE_INT_RGB);    double hScale = ((double) width) / ((double) outWidth);// 宽缩小的倍数    double vScale = ((double) height) / ((double) outHeight);// 高缩小的倍数      int winX0, winY0, winX1, winY1;    int valueRGB = 0;    long R, G, B;    int x, y, i, j;    int n;    for (y = 0; y < outHeight; y++) {     winY0 = (int) (y * vScale + 0.5);// 得到原图高的Y坐标     if (winY0 < 0) {      winY0 = 0;     }     winY1 = (int) (winY0 + vScale + 0.5);     if (winY1 > height) {      winY1 = height;     }     for (x = 0; x < outWidth; x++) {      winX0 = (int) (x * hScale + 0.5);      if (winX0 < 0) {       winX0 = 0;      }      winX1 = (int) (winX0 + hScale + 0.5);      if (winX1 > width) {       winX1 = width;      }      R = 0;      G = 0;      B = 0;      for (i = winX0; i < winX1; i++) {       for (j = winY0; j < winY1; j++) {        valueRGB = rgbArray[width * j + i];        R += getRedValue(valueRGB);        G += getGreenValue(valueRGB);        B += getBlueValue(valueRGB);       }      }      n = (winX1 - winX0) * (winY1 - winY0);      R = (int) (((double) R) / n + 0.5);      G = (int) (((double) G) / n + 0.5);      B = (int) (((double) B) / n + 0.5);      valueRGB = comRGB(clip((int) R), clip((int) G), clip((int) B));      pbFinalOut.setRGB(x, y, valueRGB);     }    }    return pbFinalOut;   }     private static int clip(int x) {    if (x < 0)     return 0;    if (x > 255)     return 255;    return x;   }     private static int getRedValue(int rgbValue) {    int temp = rgbValue & 0x00ff0000;    return temp >> 16;   }     private static int getGreenValue(int rgbValue) {    int temp = rgbValue & 0x0000ff00;    return temp >> 8;   }     private static int getBlueValue(int rgbValue) {    return rgbValue & 0x000000ff;   }     private static int comRGB(int redValue, int greenValue, int blueValue) {    return (redValue << 16) + (greenValue << 8) + blueValue;   }     /**    * 同时关闭输入流和输出流，并把可能抛出的异常转换成RuntimeException    *     * @param is    * @param os    */   public static void close(InputStream is, OutputStream os) {    close(is);    close(os);   }     /**    * 关闭输入流的工具方法，并把可能抛出的异常转换成RuntimeException    *     * @param is    */   public static void close(InputStream is) {    if (is != null) {     try {      is.close();     } catch (IOException e) {      e.printStackTrace();     }    }   }     /**    * 关闭输出流的工具方法，并把可能抛出的异常转换成RuntimeException    *     * @param os    */   public static void close(OutputStream os) {    if (os != null) {     try {      os.close();     } catch (IOException e) {      e.printStackTrace();     }    }   }  }