图片的多线程处理

public class PhotoHandle {    public static void main(String[] args) {        File file = new File("D:\\photo.bmp");        photoHandle(file, 4);//把文件分成4个线程来处理    }    public static void photoHandle(File file, int threadNumber) {        long length = file.length();        long unitLength = length/threadNumber;//把图片长度按线程数等分        for(int i=0; i

MyThread类

public class MyThread implements Runnable {    private String name;//线程名    private File file;//文件名    private long begin;//起始位置    private long end;//读取的结束位置    public MyThread(String name, File file, long begin, long end) {        this.name = name;        this.file = file;        this.begin = begin;        this.end = end;    }    @Override    public void run() {        RandomAccessFile raf = null;        try {            raf = new RandomAccessFile(file, "rw");            raf.seek(begin);// raf指针定位到最开始            while (begin <= end) {//还没到最后，则继续                int i = 255 - raf.read();                raf.seek(raf.getFilePointer() - 1);// 或raf.seek(begin)                raf.write(i);                begin++;            }            System.out.println(name + "拷贝完成!");        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } finally {            IOUtils.closeRandomAccessFile(raf);        }    }}复制代码

多线程分段示意图如下

此图同样适用于下例的文件拷贝

(大)文件的的多线程拷贝

public class MultiThreadCopy{    public static void main(String[] args) {        File sourceFile = new File("E:\\javaIO\\myeclipse.exe");//源文件地址        File targetDir = new File("e:/javaFile");//目标文件地址        int threadNumber = 4;        copyFile(sourceFile, targetDir, threadNumber);    }    public static void copyFile(File sourceFile, File targetDir, int threadNumber) {        // TODO Auto-generated method stub        if(!targetDir.exists()){            targetDir.mkdirs();        }        File targetFile = new File(targetDir, sourceFile.getName());        long length = sourceFile.length();        long unitLength = length/threadNumber;        for(int i=0; i

MyThread类

public class MyThread extends Thread{    private String name;    private File sourceFile;    private File targetDir;    private long begin;    private long end;    public MyThread(String name, File sourceFile, File targetDir, long begin, long end) {        this.name = name;        this.sourceFile = sourceFile;        this.targetDir = targetDir;        this.begin = begin;        this.end = end;    }    @Override    public void run() {        //定义读写的文件访问流        RandomAccessFile rafRead = null;        RandomAccessFile rafWrite = null;        try {            rafRead = new RandomAccessFile(sourceFile, "r");            rafWrite = new RandomAccessFile(targetDir, "rw");            //设置文件指针的开始位置和文件长度            rafWrite.setLength(end);            rafRead.seek(begin);            rafWrite.seek(begin);            int buffSize = 1024*6;            byte[] buff = new byte[buffSize];            while((begin+buffSize)<=end){                //把数据读入到buff缓冲数组中                rafRead.read(buff);                //把buff缓冲数组的数据写入到目标文件                rafWrite.write(buff);                //起始位置再向前移                begin+=buffSize;            }            //begin+buffSize超出了每一段的结尾，最后那一撮另外读            long lastSize = end-begin;            rafRead.read(buff, 0, (int) lastSize);            rafWrite.write(buff, 0, (int) lastSize);            System.out.println(this.name+"拷贝完成!");        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }finally{            IOUtils.closeRandomAccessFile(rafRead);            IOUtils.closeRandomAccessFile(rafWrite);        }    }}复制代码

IOUtils工具类

public class IOUtils {    public static void closeInputStream(InputStream is){//传入的是具体的子类        if (is != null){            try {                is.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            is = null;        }    }    public static void closeOutputStream(OutputStream os){        if (os != null){            try {                os.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            os = null;        }    }    public static void closeReader(Reader reader){        if (reader != null){            try {                reader.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            reader = null;        }    }    public static void closeWriter(Writer writer){        if (writer != null){            try {                writer.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            writer = null;        }    }    public static void closeRandomAccessFile(RandomAccessFile raf){        if (raf != null){            try {                raf.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            raf = null;        }    }}复制代码