Java常用面试题16 用IO和NIO两种方式实现文件拷贝

问：用IO和NIO两种方式实现文件拷贝

答：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;


public class MyUtil {


//// 工具类中的方法都是静态方式访问的因此将构造器私有不允许创建对象(绝对好习惯)
private MyUtil() {}


public  static void fileCopy(String source, String target)
throws IOException {
try (InputStream in = new FileInputStream(source)) {
try (OutputStream out = new FileOutputStream(target)) {
byte[] buffer = new byte[4096];
int bytesToRead;
while ((bytesToRead = in.read(buffer)) != -1) {
out.write(buffer, 0, bytesToRead);
}
}
}
}


public  static void fileCopyNIO(String source, String target)
throws IOException {
try (FileInputStream in = new FileInputStream(source)) {
try (FileOutputStream out = new FileOutputStream(target)) {
FileChannel inChannel = in.getChannel();
FileChannel outChannel = out.getChannel();
ByteBuffer buffer = ByteBuffer.allocate(4096);
while (inChannel.read(buffer) != -1) {
buffer.flip();
outChannel.write(buffer);
buffer.clear();
}
}
}
}

public static void main(String[] args) {

//获取你当前的路径

File f = new File(MyUtil.class.getClass().getResource("/").getPath()); 
System.out.println(f); 

try {
MyUtil.fileCopyNIO("F:\\WorkSpace feature\\rule_center\\target\\classes\\aa\\aa.txt", "F:\\WorkSpace feature\\rule_center\\target\\classes\\aa\\bb.txt");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

运行结果：F:\WorkSpace%20feature\rule_center\target\classes