com.aliyun.odps.io

Class BlobDataInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

java.io.DataInputStream

com.aliyun.odps.io.BlobDataInputStream

All Implemented Interfaces:

Closeable, DataInput, AutoCloseable

public abstract class BlobDataInputStream
extends DataInputStream

BlobDataInputStream是blob列类型的读取流，只能通过 InputBlobWritable.getInputStream() 接口获得该对象。

BlobDataInputStream 继承自 DataInputStream，提供了 DataInput的实现。

代码示例:

 BlobDataInputStream in = inputBlobWritable.getInputStream();
 使用in.read读取字节数组
 使用in.readType读取java基本数据类型
 in.close();
 

See Also:

DataInputStream, InputBlobWritable.getInputStream()

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BlobDataInputStream.SeekFlag BlobDataInputStream在seek时的位置标志

Constructor Summary

Constructors

Constructor and Description
BlobDataInputStream(InputStream in) 构建BlobDataInputStream对象

Method Summary

Modifier and Type	Method and Description
abstract long	getPos() 获取当前位置
abstract int	read(long position, byte[] buffer, int offset, int length) 从指定位置读取指定长度的字节
abstract void	readFully(long position, byte[] buffer) 从指定读取字节，填充满buffer传存
abstract void	readFully(long position, byte[] buffer, int offset, int length) 从指定位置读取length个字节
abstract void	seek(long offset, BlobDataInputStream.SeekFlag seekFlag) 将BlobDataInputStream的位置定位到指定位置

Methods inherited from class java.io.DataInputStream

read, read, readBoolean, readByte, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedShort, readUTF, readUTF, skipBytes

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BlobDataInputStream

public BlobDataInputStream(InputStream in)

构建BlobDataInputStream对象

Parameters:

in - 基本的数据输入流

Method Detail

seek

public abstract void seek(long offset,
                          BlobDataInputStream.SeekFlag seekFlag)
                   throws IOException

将BlobDataInputStream的位置定位到指定位置

Parameters:

offset - 偏移

seekFlag - 相对位置

Throws:

IOException

getPos

public abstract long getPos()
                     throws IOException

获取当前位置

Returns:

BlobDataInputStream的当前位置

Throws:

IOException

read

public abstract int read(long position,
                         byte[] buffer,
                         int offset,
                         int length)
                  throws IOException

从指定位置读取指定长度的字节

Parameters:

position - BlobDataInputStream的绝对位置

buffer - 读取的字节要放入的缓存

offset - 缓存的其实位置

length - 待读取的字节数

Returns:

实际读取的字节数，－1表示没有可读取的字节

Throws:

IOException

readFully

public abstract void readFully(long position,
                               byte[] buffer,
                               int offset,
                               int length)
                        throws IOException

从指定位置读取length个字节

Parameters:

position - BlobDataInputStream的绝对位置

buffer - 读取的字节要放入的缓存

offset - 缓存的起始位置

length - 待读取的字节数

Throws:

IOException - 剩余的字节数小于length时

readFully

public abstract void readFully(long position,
                               byte[] buffer)
                        throws IOException

从指定读取字节，填充满buffer传存

Parameters:

position - BlobDataInputStream的绝对位置

buffer - 读取的字节要放入的缓存

Throws:

IOException - 剩余的字节数小于传存buffer的长度时