org.apache.hadoop.util

类 LineReader

java.lang.Object

org.apache.hadoop.util.LineReader

直接已知子类:

LineRecordReader.LineReader

public class LineReader
extends Object

A class that provides a line reader from an input stream. Depending on the constructor used, lines will either be terminated by:

• one of the following: '\n' (LF) , '\r' (CR), or '\r\n' (CR+LF).
• or, a custom byte sequence delimiter

In both cases, EOF also terminates an otherwise unterminated line.

构造器概要

构造器

构造器和说明
LineReader(InputStream in) Create a line reader that reads from the given stream using the default buffer-size (64k).
LineReader(InputStream in, byte[] recordDelimiterBytes) Create a line reader that reads from the given stream using the default buffer-size, and using a custom delimiter of array of bytes.
LineReader(InputStream in, Configuration conf) Create a line reader that reads from the given stream using the io.file.buffer.size specified in the given Configuration.
LineReader(InputStream in, Configuration conf, byte[] recordDelimiterBytes) Create a line reader that reads from the given stream using the io.file.buffer.size specified in the given Configuration, and using a custom delimiter of array of bytes.
LineReader(InputStream in, int bufferSize) Create a line reader that reads from the given stream using the given buffer-size.
LineReader(InputStream in, int bufferSize, byte[] recordDelimiterBytes) Create a line reader that reads from the given stream using the given buffer-size, and using a custom delimiter of array of bytes.

方法概要

方法

限定符和类型	方法和说明
void	close() Close the underlying stream.
int	readLine(Text str) Read from the InputStream into the given Text.
int	readLine(Text str, int maxLineLength) Read from the InputStream into the given Text.
int	readLine(Text str, int maxLineLength, int maxBytesToConsume) Read one line from the InputStream into the given Text.

从类继承的方法 java.lang.Object

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

构造器详细资料

LineReader

public LineReader(InputStream in)

Create a line reader that reads from the given stream using the default buffer-size (64k).

参数:

in - The input stream

抛出:

IOException

LineReader

public LineReader(InputStream in,
          int bufferSize)

Create a line reader that reads from the given stream using the given buffer-size.

参数:

in - The input stream

bufferSize - Size of the read buffer

抛出:

IOException

LineReader

public LineReader(InputStream in,
          Configuration conf)
           throws IOException

Create a line reader that reads from the given stream using the io.file.buffer.size specified in the given Configuration.

参数:

in - input stream

conf - configuration

抛出:

IOException

LineReader

public LineReader(InputStream in,
          byte[] recordDelimiterBytes)

Create a line reader that reads from the given stream using the default buffer-size, and using a custom delimiter of array of bytes.

参数:

in - The input stream

recordDelimiterBytes - The delimiter

LineReader

public LineReader(InputStream in,
          int bufferSize,
          byte[] recordDelimiterBytes)

Create a line reader that reads from the given stream using the given buffer-size, and using a custom delimiter of array of bytes.

参数:

in - The input stream

bufferSize - Size of the read buffer

recordDelimiterBytes - The delimiter

抛出:

IOException

LineReader

public LineReader(InputStream in,
          Configuration conf,
          byte[] recordDelimiterBytes)
           throws IOException

Create a line reader that reads from the given stream using the io.file.buffer.size specified in the given Configuration, and using a custom delimiter of array of bytes.

参数:

in - input stream

conf - configuration

recordDelimiterBytes - The delimiter

抛出:

IOException

方法详细资料

close

public void close()
           throws IOException

Close the underlying stream.

抛出:

IOException

readLine

public int readLine(Text str,
           int maxLineLength,
           int maxBytesToConsume)
             throws IOException

Read one line from the InputStream into the given Text.

参数:

str - the object to store the given line (without newline)

maxLineLength - the maximum number of bytes to store into str; the rest of the line is silently discarded.

maxBytesToConsume - the maximum number of bytes to consume in this call. This is only a hint, because if the line cross this threshold, we allow it to happen. It can overshoot potentially by as much as one buffer length.

返回:

the number of bytes read including the (longest) newline found.

抛出:

IOException - if the underlying stream throws

readLine

public int readLine(Text str,
           int maxLineLength)
             throws IOException

Read from the InputStream into the given Text.

参数:

str - the object to store the given line

maxLineLength - the maximum number of bytes to store into str.

返回:

the number of bytes read including the newline

抛出:

IOException - if the underlying stream throws

readLine

public int readLine(Text str)
             throws IOException

Read from the InputStream into the given Text.

参数:

str - the object to store the given line

返回:

the number of bytes read including the newline

抛出:

IOException - if the underlying stream throws