Java IO操作的工具類總結

jopen 11年前發布 | 31K 次閱讀 Java Java開發
/**

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操作的工具類

@author yjd
*/
public class IOHelper {
 private static Logger logger = LoggerFactory.getLogger(IOHelper.class);
private IOHelper() {
 }
/**

根據指定的文件名從classpath下把該文件加載成InputStream實例

@param path
@return
*/
public static InputStream getInputStreamFromClassPath(String path) {
 return Thread.currentThread().getContextClassLoader()

     .getResourceAsStream(path);

}
/**

創建目錄

@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;
}
/**

刪除目錄

@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;
}
/**

清空指定目錄下的所有文件

@param dir
*/
public static boolean deleteSubFiles(File dir) {
 logger.debug("開始清除{}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() + "文件失敗，原因是：{}",
             dir.getAbsolutePath(), e);
 }
 logger.debug("清除{}下的所有文件, 成功{}個", dir.getAbsolutePath(), succ);
 logger.debug("清除{}下的所有文件, 失敗{}個", dir.getAbsolutePath(), fail);

}
 return flag;
}
/**

獲取指定文件的擴展名

@param fileName
@return
*/
public static String getExtend(String fileName) {
 return fileName.substring(fileName.lastIndexOf('.'));
}
/**

使用當前日期時間來產生"yyyyMMddHHmmssSSS"的字符串，主要用來做文件名

@return
*/
public static String generateFileNameByDateTime() {
 return new SimpleDateFormat("yyyyMMddHHmmssSSS").format(new Date());
}
/**

把源文件的內容復制到目標文件

@param src
源文件
@param dest
目標文件
*/
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);
}
}
/**

把源圖片srcImg縮小至指定的寬度和高度并存放至dest目標文件

@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);

}
}
/**

把源圖像縮小成指定寬高

@param srcImg
源圖片
@param outWidth
寬
@param outHeight
高
@return 壓縮后的圖像對象
*/
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);// 寬縮小的倍數
 double vScale = ((double) height) / ((double) outHeight);// 高縮小的倍數
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);// 得到原圖高的Y坐標
 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;
}
/**

同時關閉輸入流和輸出流，并把可能拋出的異常轉換成RuntimeException

@param is
@param os
*/
public static void close(InputStream is, OutputStream os) {
 close(is);
 close(os);
}
/**

關閉輸入流的工具方法，并把可能拋出的異常轉換成RuntimeException

@param is
*/
public static void close(InputStream is) {
 if (is != null) {

 try {
     is.close();
 } catch (IOException e) {
     e.printStackTrace();
 }

}
}
/**

關閉輸出流的工具方法，并把可能拋出的異常轉換成RuntimeException

@param os
*/
public static void close(OutputStream os) {
 if (os != null) {
 try {
     os.close();
 } catch (IOException e) {
     e.printStackTrace();
 }

 }
}
}</pre>
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Java Java開發
Java IO操作的工具類總結

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