文件复制.md

四种复制文件的方法

• 字节复制
• 缓冲流复制
• 使用Buffer的FileChanel
• 直接使用FileChannel

/**
 * @作者 ming
 * @目标 当你的才华还撑不起你的野心时，就应该静下心来学习；
 * 当你的能力还驾驭不了你的目标时，就应该沉下心来历练；
 * 梦想不是浮躁，而是沉淀和积累。
 * @创建时间 2020/8/9 14:29
 */
package filecopy;

import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;


public class FileCopyTest {
    public static void close(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        FileCopyRunner runner1 = (source, target) -> {
            InputStream fin = null;
            OutputStream fout = null;
            try {
                fin = new FileInputStream(source);
                fout = new FileOutputStream(target);
                int size = 0;
                while ((size = fin.read()) != -1) {
                    fout.write(size);
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                close(fin);
                close(fout);
            }
        };
        long startTime = System.currentTimeMillis();
        File sourceFile1 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\test.doc");
        File targetFile1 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\runner1.doc");
        runner1.copyFile(sourceFile1, targetFile1);
        System.out.println("runner1总耗时:" + (System.currentTimeMillis() - startTime));

        FileCopyRunner runner2 = (source, target) -> {
            InputStream fin = null;
            OutputStream fout = null;
            try {
                fin = new BufferedInputStream(new FileInputStream(source));
                fout = new BufferedOutputStream(new FileOutputStream(target));
                byte[] buffer = new byte[1024];
                while ((fin.read(buffer)) != -1) {
                    fout.write(buffer, 0, buffer.length);
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                close(fin);
                close(fout);
            }
        };
        startTime = System.currentTimeMillis();
        File sourceFile2 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\test.doc");
        File targetFile2 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\runner2.doc");
        runner1.copyFile(sourceFile2, targetFile2);
        System.out.println("runner2总耗时:" + (System.currentTimeMillis() - startTime));

        FileCopyRunner runner3 = (source, target) -> {
            FileChannel fin = null;
            FileChannel fout = null;

            try {
                fin = new FileInputStream(source).getChannel();
                fout = new FileOutputStream(target).getChannel();
                ByteBuffer buffer = ByteBuffer.allocate(1024);
                while (fin.read(buffer) != -1) {
                    // 切换为写模式
                    buffer.flip();
                    while (buffer.hasRemaining()) {
                        fout.write(buffer);
                    }
                    // 切换为读模式
                    buffer.clear();
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                close(fin);
                close(fout);
            }
        };
        startTime = System.currentTimeMillis();
        File sourceFile3 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\test.doc");
        File targetFile3 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\runner3.doc");
        runner1.copyFile(sourceFile3, targetFile3);
        System.out.println("runner3总耗时:" + (System.currentTimeMillis() - startTime));

        FileCopyRunner runner4 = (source, target) -> {
            FileChannel fin = null;
            FileChannel fout = null;

            try {
                fin = new FileInputStream(source).getChannel();
                fout = new FileOutputStream(target).getChannel();
                long totalSize = 0;
                while (totalSize != fin.size()) {
                    totalSize += fin.transferTo(0, fin.size(), fout);
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                close(fin);
                close(fout);
            }
        };
        startTime = System.currentTimeMillis();
        File sourceFile4 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\test.doc");
        File targetFile4 = new File("D:\\IDEA Pro\\sockets\\src\\filecopy\\runner4.doc");
        runner1.copyFile(sourceFile4, targetFile4);
        System.out.println("runner4总耗时:" + (System.currentTimeMillis() - startTime));
    }
}