org.springframework.batch.item.file
Class FlatFileItemReader

java.lang.Object
  org.springframework.batch.item.ExecutionContextUserSupport
      org.springframework.batch.item.file.FlatFileItemReader

All Implemented Interfaces:

ItemReader, ItemStream, InitializingBean

public class FlatFileItemReader
extends ExecutionContextUserSupport
implements ItemReader, ItemStream, InitializingBean

This class represents a ItemReader, that reads lines from text file, tokenizes them to structured tuples (FieldSets) instances and maps the FieldSets to domain objects. The location of the file is defined by the resource property. To separate the structure of the file, LineTokenizer is used to parse data obtained from the file.
A FlatFileItemReader is not thread safe because it maintains state in the form of a ResourceLineReader. Be careful to configure a FlatFileItemReader using an appropriate factory or scope so that it is not shared between threads.

This class supports restart, skipping invalid lines and storing statistics. It can be configured to setup FieldSet column names from the file header, skip given number of lines at the beginning of the file.

Author:

Waseem Malik, Tomas Slanina, Robert Kasanicky, Dave Syer

Field Summary

static String

DEFAULT_CHARSET

Constructor Summary

FlatFileItemReader()

Method Summary

void	afterPropertiesSet()
void	close(ExecutionContext executionContext) Close and null out the reader.
protected LineReader	getReader()
void	mark() Mark is supported as long as this ItemStream is used in a single-threaded environment.
void	open(ExecutionContext executionContext) Initialize the reader if necessary.
Object	read() Reads a line from input, tokenizes is it using the setLineTokenizer(LineTokenizer) and maps to domain object using setFieldSetMapper(FieldSetMapper).
void	reset() Reset the stream to the last mark.
void	setComments(String[] comments) Setter for comment prefixes.
void	setEncoding(String encoding) Setter for the encoding for this input source.
void	setFieldSetMapper(FieldSetMapper fieldSetMapper) Set the FieldSetMapper to be used for each line.
void	setFirstLineIsHeader(boolean firstLineIsHeader) Indicates whether first line is a header.
void	setLinesToSkip(int linesToSkip) Public setter for the number of lines to skip at the start of a file.
void	setLineTokenizer(LineTokenizer lineTokenizer)
void	setRecordSeparatorPolicy(RecordSeparatorPolicy recordSeparatorPolicy) Public setter for the recordSeparatorPolicy.
void	setResource(Resource resource) Setter for resource property.
void	setSaveState(boolean saveState) Set the boolean indicating whether or not state should be saved in the provided ExecutionContext during the ItemStream call to update.
void	update(ExecutionContext executionContext) This method returns the execution attributes for the reader.

Methods inherited from class org.springframework.batch.item.ExecutionContextUserSupport

getKey, setName

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CHARSET

public static final String DEFAULT_CHARSET

See Also:

Constant Field Values

Constructor Detail

FlatFileItemReader

public FlatFileItemReader()

Method Detail

open

public void open(ExecutionContext executionContext)
          throws ItemStreamException

Initialize the reader if necessary.

Specified by:

open in interface ItemStream

Throws:

IllegalStateException - if the resource cannot be opened

ItemStreamException

close

public void close(ExecutionContext executionContext)
           throws ItemStreamException

Close and null out the reader.

Specified by:

close in interface ItemStream

Parameters:

executionContext - TODO

Throws:

ItemStreamException

read

public Object read()
            throws Exception

Reads a line from input, tokenizes is it using the setLineTokenizer(LineTokenizer) and maps to domain object using setFieldSetMapper(FieldSetMapper).

Specified by:

read in interface ItemReader

Throws:

Exception - if an underlying resource is unavailable.

See Also:

ItemReader.read()

update

public void update(ExecutionContext executionContext)

This method returns the execution attributes for the reader. It returns the current Line Count which can be used to reinitialise the batch job in case of restart.

Specified by:

update in interface ItemStream

Parameters:

executionContext - to be updated

mark

public void mark()

Mark is supported as long as this ItemStream is used in a single-threaded environment. The state backing the mark is a single counter, keeping track of the current position, so multiple threads cannot be accommodated.

Specified by:

mark in interface ItemReader

See Also:

ItemReader.mark()

reset

public void reset()

Description copied from interface: ItemReader

Reset the stream to the last mark. After a reset the stream state will be such that changes (items read or written) since the last call to mark will not be visible after a call to close.
In a multi-threaded setting implementations have to ensure that only the state from the current thread is reset.

Specified by:

reset in interface ItemReader

getReader

protected LineReader getReader()

Returns:

line reader used to read input file

setResource

public void setResource(Resource resource)

Setter for resource property. The location of an input stream that can be read.

Parameters:

resource -

setRecordSeparatorPolicy

public void setRecordSeparatorPolicy(RecordSeparatorPolicy recordSeparatorPolicy)

Public setter for the recordSeparatorPolicy. Used to determine where the line endings are and do things like continue over a line ending if inside a quoted string.

Parameters:

recordSeparatorPolicy - the recordSeparatorPolicy to set

setComments

public void setComments(String[] comments)

Setter for comment prefixes. Can be used to ignore header lines as well by using e.g. the first couple of column names as a prefix.

Parameters:

comments - an array of comment line prefixes.

setFirstLineIsHeader

public void setFirstLineIsHeader(boolean firstLineIsHeader)

Indicates whether first line is a header. If the tokenizer is an AbstractLineTokenizer and the column names haven't been set already then the header will be used to setup column names. Default is false.

setLineTokenizer

public void setLineTokenizer(LineTokenizer lineTokenizer)

Parameters:

lineTokenizer - tokenizes each line from file into FieldSet.

setFieldSetMapper

public void setFieldSetMapper(FieldSetMapper fieldSetMapper)

Set the FieldSetMapper to be used for each line.

Parameters:

fieldSetMapper -

setLinesToSkip

public void setLinesToSkip(int linesToSkip)

Public setter for the number of lines to skip at the start of a file. Can be used if the file contains a header without useful (column name) information, and without a comment delimiter at the beginning of the lines.

Parameters:

linesToSkip - the number of lines to skip

setEncoding

public void setEncoding(String encoding)

Setter for the encoding for this input source. Default value is DEFAULT_CHARSET.

Parameters:

encoding - a properties object which possibly contains the encoding for this input file;

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Specified by:

afterPropertiesSet in interface InitializingBean

Throws:

Exception

setSaveState

public void setSaveState(boolean saveState)

Set the boolean indicating whether or not state should be saved in the provided ExecutionContext during the ItemStream call to update. Setting this to false means that it will always start at the beginning.

Parameters:

saveState -