Java IO1 复制粘贴文件

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;

import com.sun.xml.internal.bind.v2.runtime.unmarshaller.XsiNilLoader.Array;

public class Copy {
/**
 * 文件复制
 * @param
 * @param
 * 
 */
public Copy() {
// TODO Auto-generated constructor stub
}

public static void cp(File src, File desc) {
//使用输入流从源读取(接收)
InputStream in = null;
OutputStream out = null;

try {
//打开目标文件
in = new FileInputStream(src);
out = new FileOutputStream(desc);
//读，写
byte[] buf = new byte[4];
//in.read() 读一个字节，返回的是字节(读到的数据本身)
//in.read(buf) 读取放入buf，会一直往前读，读完了，缓冲满了，返回的是读到的数据的数量
int size ;

while(-1 != (size = in.read(buf))) {
//如果这样的话会出现倒数第二次留下的以前的脏数据
//out.write(buf); 
//每次写入剩下的size，避免写入的了脏垃圾
out.write(buf, 0, size);
size = in.read();
System.out.println(Arrays.toString(buf));
}
System.out.println("ok");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
//出错才执行
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
//都执行
if(in != null) {
//成功打开 in
try {
in.close();
} catch (IOException e2) {
// TODO: handle exception
in = null;
}
}
}
}
}

import java.io.File;

public class Test {
public static void main(String args[]) {
Copy.cp(new File("a.txt"), new File("b.txt"));
}
}