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package com.boot.demo.test.io;
import java.io.*;
import java.lang.reflect.Method;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* @author braska
* @date 2020/3/19
**/
public class FileTest {
public static void fileStream(String sourceFile, String targetFile) {
File file = new File(targetFile);
try (FileInputStream fis = new FileInputStream(sourceFile);
FileOutputStream fos = new FileOutputStream(file)) {
byte[] bytes = new byte[1024 * 1024];
int len;
while ((len = fis.read(bytes)) > 0) {
fos.write(bytes, 0, len);
}
} catch (Exception e) {
}
}
public static void bufferStream(String sourceFile, String targetFile) {
try (BufferedInputStream bis = new BufferedInputStream(Files.newInputStream(Paths.get(sourceFile)));
BufferedOutputStream bos =
new BufferedOutputStream(Files.newOutputStream(Paths.get(targetFile),
StandardOpenOption.CREATE,
StandardOpenOption.TRUNCATE_EXISTING,
StandardOpenOption.WRITE))) {
byte[] bytes = new byte[1024 * 1024];
int len;
while ((len = bis.read(bytes)) > 0) {
bos.write(bytes, 0, len);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void randomFile(String sourceFile, String targetFile) {
try (RandomAccessFile read = new RandomAccessFile(sourceFile, "r");
RandomAccessFile write = new RandomAccessFile(targetFile, "rw")) {
byte[] bytes = new byte[1024 * 1024];
int len;
while ((len = read.read(bytes)) > 0) {
write.write(bytes, 0, len);
}
} catch (Exception e) {
}
}
public static void memoryMap(String sourceFile, String targetFile) {
try (FileChannel rc = FileChannel.open(Paths.get(sourceFile));
FileChannel wc = FileChannel.open(Paths.get(targetFile),
StandardOpenOption.CREATE,
StandardOpenOption.READ,
StandardOpenOption.TRUNCATE_EXISTING,
StandardOpenOption.WRITE)) {
long copy = 1L << 30;
long cur = 0;
long fileLength = rc.size();
while (cur < fileLength) {
copy = cur + copy > fileLength ? (fileLength - cur) : copy;
MappedByteBuffer rMap = rc.map(FileChannel.MapMode.READ_ONLY, cur, copy);
MappedByteBuffer wMap = wc.map(FileChannel.MapMode.READ_WRITE, cur, copy);
for (int i = 0; i < copy; i++) {
byte b = rMap.get(i); //从源文件读取字节
wMap.put(i, b); //把字节写到目标文件中
}
System.gc(); //手动调用 GC <必须的，否则出现异常>
System.runFinalization();
cur += copy;
}
} catch (Exception e) {
e.printStackTrace();
}
}
private static String buildFilePath(String path, String fileName, String extension) {
return String.format("%s%s.%s", path, fileName, extension);
}
public static void main(String[] args) {
/* String path = "F:\\workspace\\demo\\";
String extension = "hprof";
// 30M文件
String sourceFile = buildFilePath(path, "01", extension);*/
/* String path = "E:\\software\\";
String extension = "exe";
// 460M文件
String sourceFile = buildFilePath(path, "Anaconda3-2019.10-Windows-x86_64", extension);*/
String path = "E:\\software\\";
String extension = "zip";
// 1.47G文件
String sourceFile = buildFilePath(path, "software", extension);
String targetFile;
long start;
/* targetFile = buildFilePath(path, "target_file_stream", extension);
start = System.currentTimeMillis();
FileTest.fileStream(sourceFile, targetFile);
System.out.println("file stream used time:" + (System.currentTimeMillis() - start));*/
/* targetFile = buildFilePath(path, "target_buffer_stream", extension);
start = System.currentTimeMillis();
FileTest.bufferStream(sourceFile, targetFile);
System.out.println("buffer stream used time:" + (System.currentTimeMillis() - start));*/
/* targetFile = buildFilePath(path, "target_random_file", extension);
start = System.currentTimeMillis();
FileTest.randomFile(sourceFile, targetFile);
System.out.println("random file used time:" + (System.currentTimeMillis() - start));*/
targetFile = buildFilePath(path, "target_memory_map", extension);
start = System.currentTimeMillis();
FileTest.memoryMap(sourceFile, targetFile);
System.out.println("memory map used time:" + (System.currentTimeMillis() - start));
}
}
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