如何用原始InputStream实例化FSDataInputStream？
我真的不知道如何创建这样的inputStream，它是Seekable和PositionedReadable ...
Resource resource = new ClassPathResource("somefile");
InputStream bla = resource.getInputStream();
FSDataInputStream inputStream = new FSDataInputStream (bla);
在FS线投掷：
java.lang.IllegalArgumentException: In is not an instance of Seekable or PositionedReadable
我需要做嘲笑，这对我来说是一个阻碍。
FSDataInputStream构造函数，如下所示，在FSDataInputStream.java中定义，它需要InputStream参数为Seekable或PositionedReadable的instance
public FSDataInputStream(InputStream in) throws IOException
{
super(in);
if( !(in instanceof Seekable) || !(in instanceof PositionedReadable) ) {
throw new IllegalArgumentException(
"In is not an instance of Seekable or PositionedReadable");
}
}
希望以下solution可帮助您
import java.io.*;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.PositionedReadable;
import org.apache.hadoop.fs.Seekable;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
public class SeekableTest {
public static void main(String[] args) throws IOException
{
Resource resource = new ClassPathResource("somefile");
InputStream in = resource.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte buf[] = new byte[1024];
int read;
while ((read = in.read(buf)) > 0)
baos.write(buf, 0, read);
byte data[] = baos.toByteArray();
SeekableByteArrayInputStream bais = new SeekableByteArrayInputStream(data);
FSDataInputStream in2 = new FSDataInputStream(bais);
}
static class SeekableByteArrayInputStream extends ByteArrayInputStream implements Seekable, PositionedReadable {
public SeekableByteArrayInputStream(byte[] buf)
{
super(buf);
}
@Override
public long getPos() throws IOException{
return pos;
}
@Override
public void seek(long pos) throws IOException {
if (mark != 0)
throw new IllegalStateException();
reset();
long skipped = skip(pos);
if (skipped != pos)
throw new IOException();
}
@Override
public boolean seekToNewSource(long targetPos) throws IOException {
return false;
}
@Override
public int read(long position, byte[] buffer, int offset, int length) throws IOException {
if (position >= buf.length)
throw new IllegalArgumentException();
if (position + length > buf.length)
throw new IllegalArgumentException();
if (length > buffer.length)
throw new IllegalArgumentException();
System.arraycopy(buf, (int) position, buffer, offset, length);
return length;
}
@Override
public void readFully(long position, byte[] buffer) throws IOException {
read(position, buffer, 0, buffer.length);
}
@Override
public void readFully(long position, byte[] buffer, int offset, int length) throws IOException {
read(position, buffer, offset, length);
}
}
}
参考：accumulo
链接地址: http://www.djcxy.com/p/21905.html上一篇: How to instantiate FSDataInputStream with raw InputStream?