Java文件复制

Java文件复制代码如下：

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 FileCope {
	
	/***
	 * 方式一：使用文件流复制
	 */	
	public static void copyFile(String source, String target) {
		InputStream in = null;
		OutputStream out = null;
		try {
			in = new FileInputStream(source);
			out = new FileOutputStream(target);
			byte[] buffer = new byte[2048];
			int readBuffer;
			while ((readBuffer = in.read(buffer)) != -1) { // 从输入流中读取一定数量的字节，并将其存储在缓冲区数组buffer中。
				out.write(buffer, 0, readBuffer); // buffer数组中从偏移量为0开始的readBuffer个字节写入到out输出流。
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				out.close();
				in.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
	
	
	/***
	 * 方式二：使用Try-with-resources (TWR)进行复制
	 */	
	public static void copyFileTWR(String source, String target)throws IOException{
		try (InputStream in = new FileInputStream(source)) {
			try (OutputStream out = new FileOutputStream(target)) {
				byte[] buffer = new byte[2048];
				int bytesToRead;
				while ((bytesToRead = in.read(buffer)) != -1) {
					out.write(buffer, 0, bytesToRead);
				}
			}
		}
	}


	/***
	 * 方式三：使用FileChannel复制
	 */	
	public static void copyFileNIO(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(2048);  //分配一个大小为2048的字节缓冲区。
				while (inChannel.read(buffer) != -1) {
					buffer.flip();                        //反转缓冲区。通常情况下，在准备从缓冲区中读取数据时调用flip方法。
					outChannel.write(buffer);
					buffer.clear();
				}
			}
		}
	}
	
	public static void main(String args[]){		
		copyFile("E://1.txt","E://2.text");
		try {
			copyFileTWR("E://2.txt","E://3.txt");
			copyFileNIO("E://3.txt","E://4.text");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}		
	}
}