com.aliyun.odps.io

Interface InputBlobWritable

All Superinterfaces:

Comparable, Writable, WritableComparable

public interface InputBlobWritable
extends WritableComparable

InputBlobWritable表示ODPS表或分区中列类型为blob的输入接口. 该接口只能用于 com.aliyun.odps.mapreduce.Mapper从 com.aliyun.odps.Record 中读取blob类型的列.

用法示例：

 @Override
 public void map(LongWritable key, Record value,
     MapContext<KEYOUT, VALUEOUT> context) throws IOException {
   InputBlobWritable blob = value.get(0);
   BlobDataInputStream in = blob.getInputStream();
   long length = in.getLength();
   // 使用in.read从blob中读取
   in.close();
 }
 

从上面的示例看出, 从com.aliyun.odps.Record获得InputBlobWritable接口, 调用InputBlobWritable的getInputStream获得BlobDataInputStream后, 即可读出数据.

Method Summary

Modifier and Type	Method and Description
BlobDataInputStream	getInputStream() getInputStream方法获取可以读取blob的BlobDataInputStream接口
long	getLength() getLength方法获取blob的总字节数

Methods inherited from interface com.aliyun.odps.io.Writable

readFields, write

Methods inherited from interface java.lang.Comparable

compareTo

Method Detail

getInputStream

BlobDataInputStream getInputStream()
                            throws IOException

getInputStream方法获取可以读取blob的BlobDataInputStream接口

Returns:

blob列对应的BlobDataInputStream

Throws:

IOException

getLength

long getLength()
        throws IOException

getLength方法获取blob的总字节数

Returns:

blob列的字节数

Throws:

IOException