文件分段读取示例，分段读取示例,package my.t

文件分段读取示例，分段读取示例,package my.t

package my.test;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.RandomAccessFile;public class ImageFileCopy {    /**     * @param args     */    public static void main(String[] args) {        String prePath = "D:\\\\testFile\\\\test.jpg";        String curPath = "";        copyImgFile(prePath, curPath);    }    /**     * 文件图像文件     * @param prePath   图片之前存放路径     * @param curPath   图片拷贝之后存放路径     */    private static void copyImgFile(String prePath, String curPath) {        long segmentLength = 1024 * 1024;   //1M大小        try {            RandomAccessFile randomAccessFile = new RandomAccessFile(prePath, "r");            File tempFile = new File("D:\\\\testFile\\\\", "temp.jpg");            FileOutputStream fileOutputStream = new FileOutputStream(tempFile, true);            int currentSegment = 0;            int count = (int)(randomAccessFile.length() / segmentLength ) + (randomAccessFile.length() % segmentLength > 0 ? 1 : 0);            for(int i = 0; i < count; i++) {                currentSegment = i + 1;                System.out.println("分段：" + currentSegment);                randomAccessFile.seek(i * segmentLength);                long toal = 0; //当前已读取的长度                int read = 0; //一次读取的长度                int bufferLenght = 500 * 1024; //缓存长度                byte[] buffer = new byte[bufferLenght];                while ((read = randomAccessFile.read(buffer, 0, bufferLenght)) > 0) {                    System.out.println("bufferLength:" + bufferLenght);                    fileOutputStream.write(buffer, 0, read);                    toal += read;                    bufferLenght = (int) ((toal + bufferLenght) > segmentLength ? segmentLength - toal : bufferLenght);                }                /*long toal = 0; //当前已读取的长度                int read = 0; //一次读取的长度                int bufferLenght = 500 * 1024; //缓存长度                int bufferLenghtTemp = bufferLenght;                byte[] buffer = new byte[bufferLenght];                while ((read = randomAccessFile.read(buffer, 0, bufferLenght)) > 0) {                    fileOutputStream.write(buffer, 0, read);                    toal += read;                    //bufferLenght = (int) ((toal + bufferLenght) > segmentLength ? segmentLength - toal : bufferLenght);                    if(toal >= segmentLength) break;                    else                    {                        if((toal + bufferLenghtTemp) >= segmentLength) bufferLenght = bufferLenghtTemp;                        else bufferLenght = (int) (bufferLenghtTemp - toal);                    }                }*/            }            fileOutputStream.flush();            fileOutputStream.close();            System.out.println("源文件大小：" + randomAccessFile.length() + " , 拷贝后文件大小：" + tempFile.length());        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }     }}//该片段来自于http://byrx.net