package com.pb.thread.demo;import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;import java.io.RandomaccessFile;/** * 多線程復(fù)制文件工具類 *  * @author denny * */public class MutiCopyFileUtil {    PRivate String src;// 源文件    private String dst;// 目標(biāo)文件    private int threadSize;// 開(kāi)啟多少個(gè)線程去復(fù)制源文件    /**     * 包含3個(gè)參數(shù)的構(gòu)造方法     *      * @param src     *            源文件     * @param dst     *            目標(biāo)文件     * @param threadSize     *            開(kāi)啟多少個(gè)線程去復(fù)制源文件     */    public MutiCopyFileUtil(String src, String dst, int threadSize) {        super();        this.src = src;        this.dst = dst;        this.threadSize = threadSize;    }    /**     * 復(fù)制文件的方法     */    public void copyFile() {        File file = new File(src);// 源文件的File對(duì)象        // 獲取源文件大小字節(jié)數(shù)        long fsize = file.length();        // 計(jì)算每個(gè)線程下載的字節(jié)數(shù)        long block = fsize % threadSize == 0 ? fsize / threadSize : fsize / threadSize + 1;        // 開(kāi)啟循環(huán)調(diào)用        for (int threadId = 0; threadId < threadSize; threadId++) {            // 開(kāi)啟多個(gè)個(gè)線程來(lái)進(jìn)行文件的復(fù)制，            new DownloadThread(fsize, block, threadId).start();        }    }    /**     *      * @author denny     *     */    private class DownloadThread extends Thread {        private long fsize;// 文件大小        private long block;// 每個(gè)線程下載的字節(jié)數(shù)        private int threadId;// 線程的ID號(hào),從0開(kāi)始        private int buffSize=1024*1024; //緩沖區(qū)大小        public DownloadThread(long fsize, long block, int threadId) {            super();            this.fsize = fsize;            this.block = block;            this.threadId = threadId;        }        /**         * 重寫run方法         */        public void run() {            try {                // 隨機(jī)訪問(wèn)文件對(duì)象 聲明IO類，以只讀的模式訪問(wèn)文件                RandomAccessFile reader = new RandomAccessFile(src, "r");                // 隨機(jī)訪問(wèn)文件對(duì)象                RandomAccessFile writer = new RandomAccessFile(dst, "rw");                // 每個(gè)線程下載的啟始位置                long startPos = threadId * block;                // 確定每個(gè)線程下載的結(jié)束位置                long endPos = startPos + block > fsize ? fsize : startPos + block;                /*                 * 判斷下載的結(jié)束位置是不是比文件最大的位置還大，                  * 是的話就是文件的最大位置，                  * 不是的話就是開(kāi)始位置+要下載的字節(jié)大小                 */                                //設(shè)置游標(biāo)的位置                reader.seek(startPos);                //設(shè)置目標(biāo)文件的                writer.seek(startPos);                //設(shè)置緩沖區(qū)                byte[] buf=new byte[buffSize];                while(startPos<endPos){                    int len=0;                    //判斷是不是到結(jié)束位置                    if(startPos+buffSize<endPos){                        //讀取文件到緩沖區(qū),讀滿                        len=reader.read(buf);                                            }else{                            //把剩下的填不滿緩沖區(qū)的數(shù)據(jù)寫到緩沖區(qū)中                        len=reader.read(buf, 0, (int)(endPos-startPos));                    }                    //改變起始位置                    startPos+=len;                    /*寫入目標(biāo)文件                     * 把緩沖區(qū)的文件寫入目標(biāo)文件                    */                    writer.write(buf,0,len);                    System.out.println("線程"+(threadId+1)+"下載了:"+len);                }                reader.close();                writer.close();                System.out.println("線程"+(threadId+1)+"下載完畢");            } catch (IOException e) {                e.printStackTrace();            }        }    }}

package com.pb.thread.demo;import java.io.File;/** *  * @author denny * */public class MutiCopyFileDemo {    public static void main(String[] args) {        /*         * /home/denny/Downloads         * android-studio-ide-141.2135290-linux.zip         */        String src="/home/denny/Downloads/android-studio-ide-141.2135290-linux.zip";        String dst="/home/denny/Downloads/a.zip";        MutiCopyFileUtil mcf=new MutiCopyFileUtil(src,dst,10);        mcf.copyFile();    }}

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