使用多线程以及RandomAccessfile来实现多线程复制文件

  1 package com.edu.testThreadDlFile;
  2 
  3 import java.io.File;
  4 import java.io.FileNotFoundException;
  5 import java.io.IOException;
  6 import java.io.RandomAccessFile;
  7 import java.util.concurrent.TimeUnit;
  8 
  9 /**
 10  * @作者 five-five
 11  * @创建时间 2020/10/15
 12  */
 13 public class DownloadUtil {
 14     private File fromFile;//源文件
 15     private File toFile;//要拷贝到的地方
 16     private int threadNum;//线程数量
 17 
 18     //下载的方法
 19     public void doDownLoad() {
 20         System.out.println(fromFile.length());
 21         for (int i=0;i<threadNum;i++){
 22             MydownLoadThread thread = new MydownLoadThread(i);
 23             thread.setName("线程"+(i+1));
 24             System.out.println(thread.getName()+"的任务量是	"+thread.getBlockSize());
 25             thread.start();
 26         }
 27         System.out.println("文件上传完毕");
 28     }
 29 
 30     public DownloadUtil() {
 31     }
 32 
 33     public DownloadUtil(File fromFile, File toFile, int threadNum) {
 34         this.fromFile = fromFile;
 35         this.toFile = toFile;
 36         this.threadNum = threadNum;
 37     }
 38 
 39     class MydownLoadThread extends Thread {
 40 
 41         private volatile int index;//表示第几个线程
 42         private long blockSize = fromFile.length() % threadNum == 0
 43                 ? fromFile.length() / threadNum
 44                 : fromFile.length() / threadNum + (fromFile.length() % threadNum); //每个线程下载的文件大小
 45         private volatile long startPos;//起始位置
 46 
 47         /**
 48          * 第多少个线程
 49          *
 50          * @param index
 51          */
 52         public MydownLoadThread(int index) {
 53             this.index = index;
 54             startPos = index * blockSize;//计算下载了多少
 55         }
 56 
 57         @Override
 58         public void run() {
 59             RandomAccessFile rf = null;
 60             RandomAccessFile wf = null;
 61             try {
 62 //                System.out.println("起始位置"+startPos);
 63                 //"r", "rw", "rws", or "rwd"
 64                 rf = new RandomAccessFile(fromFile, "r");//只读
 65                 wf = new RandomAccessFile(toFile, "rw");//只写
 66                 rf.seek(startPos);
 67                 wf.seek(startPos);
 68                 byte[] buf = new byte[1024 * 1024];//缓存区为1MB
 69                 int len = -1;
 70                 do {
 71                     //记录每次读取的大小(缓冲区可能大于线程任务量)
 72                     len = blockSize > buf.length ? buf.length : (int) blockSize;
 73                     //io操作
 74                     rf.read(buf, 0, len);
 75                     wf.write(buf, 0, len);
 76                     blockSize -= len;
 77                     System.out.println(Thread.currentThread().getName() + "读取了" + len + "个字节");
 78                 } while (blockSize>0);
 79                 wf.close();
 80                 rf.close();
 81 //                TimeUnit.SECONDS.sleep(1);//每次睡一秒
 82             } catch (Exception e) {
 83                 e.printStackTrace();
 84             }
 85         }
 86 
 87         public int getIndex() {
 88             return index;
 89         }
 90 
 91         public void setIndex(int index) {
 92             this.index = index;
 93         }
 94 
 95         public long getBlockSize() {
 96             return blockSize;
 97         }
 98 
 99         public void setBlockSize(long blockSize) {
100             this.blockSize = blockSize;
101         }
102 
103         public long getStartPos() {
104             return startPos;
105         }
106 
107         public void setStartPos(long startPos) {
108             this.startPos = startPos;
109         }
110     }
111 
112     public File getFromFile() {
113         return fromFile;
114     }
115 
116     public void setFromFile(File fromFile) {
117         this.fromFile = fromFile;
118     }
119 
120     public File getToFile() {
121         return toFile;
122     }
123 
124     public void setToFile(File toFile) {
125         this.toFile = toFile;
126     }
127 
128     public int getThreadNum() {
129         return threadNum;
130     }
131 
132     public void setThreadNum(int threadNum) {
133         this.threadNum = threadNum;
134     }
135 }