1. 字节流
@Test
public void test4() throws IOException {
File src = new File("2.png");
File dest = new File("2_copy.png");
FileInputStream fis = new FileInputStream(src);
FileOutputStream fos = new FileOutputStream(dest);
byte[] bytes = new byte[1024];
int len;
while((len=fis.read(bytes))!=-1){
fos.write(bytes,0,len);
}
fis.close();
fos.close();
}