java8中nio通道(Channel)的基本使用
1、利用通道完成文件的复制
@Test
public void test4() throws Exception{
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"),
StandardOpenOption.READ);
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"),
StandardOpenOption.WRITE,
StandardOpenOption.READ,StandardOpenOption.CREATE_NEW);
//inChannel.transferTo(0,inChannel.size(),outChannel);
outChannel.transferFrom(inChannel,0,inChannel.size());
inChannel.close();
outChannel.close();
}
2、使用直接缓冲区完成文件的复制(内存映射文件)
@Test
public void test2() throws Exception{
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"),StandardOpenOption.WRITE,StandardOpenOption.CREATE_NEW);
//内存映射文件
MappedByteBuffer inMappedBuff = inChannel.map(FileChannel.MapMode.READ_ONLY,0,inChannel.size());
MappedByteBuffer outMappedBuff = outChannel.map(FileChannel.MapMode.READ_WRITE,0,inChannel.size());
//直接对缓冲区进行数据的读写操作
byte[] dst = new byte[inMappedBuff.limit()];
inMappedBuff.get(dst);
outMappedBuff.put(dst);
}
3、通道之间的数据传输
@Test
public void test4() throws Exception{
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"),
StandardOpenOption.READ);
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"),
StandardOpenOption.WRITE,
StandardOpenOption.READ,StandardOpenOption.CREATE_NEW);
inChannel.transferTo(0,inChannel.size(),outChannel);
}
4、通道之间的数据传输(直接缓冲区)
@Test
public void test4() throws Exception{
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"),
StandardOpenOption.READ);
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"),
StandardOpenOption.WRITE,
StandardOpenOption.READ,StandardOpenOption.CREATE_NEW);
outChannel.transferFrom(inChannel,0,inChannel.size());
}
5、关闭输入通道连接
@Test
public void test4() throws Exception{
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"),
StandardOpenOption.READ);
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"),
StandardOpenOption.WRITE,
StandardOpenOption.READ,StandardOpenOption.CREATE_NEW);
outChannel.transferFrom(inChannel,0,inChannel.size());
inChannel.close();
}
6、关闭输出通道连接
@Test
public void test4() throws Exception{
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"),
StandardOpenOption.READ);
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"),
StandardOpenOption.WRITE,
StandardOpenOption.READ,StandardOpenOption.CREATE_NEW);
outChannel.transferFrom(inChannel,0,inChannel.size());
inChannel.close();
outChannel.close();
}
