問：用IO和NIO兩種方式實現檔案拷貝

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 {


//// 工具類中的方法都是靜態方式訪問的因此將構造器私有不允許建立物件(絕對好習慣)
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) {

//獲取你當前的路徑

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();
}
}
}

執行結果：F:\WorkSpace%20feature\rule_center\target\classes