java.lang.Object
- org.apache.beam.sdk.io.FileBasedSink.Writer<DestinationT,OutputT>

Type Parameters:

OutputT - the type of values to write.

Enclosing class:

FileBasedSink<UserT,DestinationT,OutputT>
```
public abstract static class FileBasedSink.Writer<DestinationT,OutputT>
extends java.lang.Object
```
Abstract writer that writes a bundle to a FileBasedSink. Subclass implementations provide a method that can write a single value to a WritableByteChannel.
Subclass implementations may also override methods that write headers and footers before and after the values in a bundle, respectively, as well as provide a MIME type for the output channel.
Multiple FileBasedSink.Writer instances may be created on the same worker, and therefore any access to static members or methods should be thread safe.

Constructor Summary

Constructors
Constructor	Description
`Writer(FileBasedSink.WriteOperation<DestinationT,OutputT> writeOperation, java.lang.String mimeType)`	Construct a new `FileBasedSink.Writer` that will produce files of the given MIME type.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`cleanup()`
`void`	`close()`	Closes the channel and returns the bundle result.
`protected void`	`finishWrite()`	Called after all calls to `writeHeader()`, `write(OutputT)` and `writeFooter()`.
`DestinationT`	`getDestination()`	Return the user destination object for this writer.
`ResourceId`	`getOutputFile()`
`FileBasedSink.WriteOperation<DestinationT,OutputT>`	`getWriteOperation()`	Return the WriteOperation that this Writer belongs to.
`void`	`open(java.lang.String uId)`	Opens a uniquely named temporary file and initializes the writer using `prepareWrite(java.nio.channels.WritableByteChannel)`.
`protected abstract void`	`prepareWrite(java.nio.channels.WritableByteChannel channel)`	Called with the channel that a subclass will write its header, footer, and values to.
`abstract void`	`write(OutputT value)`	Called for each value in the bundle.
`protected void`	`writeFooter()`	Writes footer at the end of output files.
`protected void`	`writeHeader()`	Writes header at the beginning of output files.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Writer
```
public Writer(FileBasedSink.WriteOperation<DestinationT,OutputT> writeOperation,
              java.lang.String mimeType)
```
    Construct a new FileBasedSink.Writer that will produce files of the given MIME type.
- Method Detail
  - prepareWrite
```
protected abstract void prepareWrite(java.nio.channels.WritableByteChannel channel)
                              throws java.lang.Exception
```
    Called with the channel that a subclass will write its header, footer, and values to. Subclasses should either keep a reference to the channel provided or create and keep a reference to an appropriate object that they will use to write to it.
    Called before any subsequent calls to writeHeader, writeFooter, and write.
    
    Throws:
    
    java.lang.Exception
  - writeHeader
```
protected void writeHeader()
                    throws java.lang.Exception
```
    Writes header at the beginning of output files. Nothing by default; subclasses may override.
    
    Throws:
    
    java.lang.Exception
  - writeFooter
```
protected void writeFooter()
                    throws java.lang.Exception
```
    Writes footer at the end of output files. Nothing by default; subclasses may override.
    
    Throws:
    
    java.lang.Exception
  - finishWrite
```
protected void finishWrite()
                    throws java.lang.Exception
```
    Called after all calls to writeHeader(), write(OutputT) and writeFooter(). If any resources opened in the write processes need to be flushed, flush them here.
    
    Throws:
    
    java.lang.Exception
  - open
```
public final void open(java.lang.String uId)
                throws java.lang.Exception
```
    Opens a uniquely named temporary file and initializes the writer using prepareWrite(java.nio.channels.WritableByteChannel).
    The unique id that is given to open should be used to ensure that the writer's output does not interfere with the output of other Writers, as a bundle may be executed many times for fault tolerance.
    
    Throws:
    
    java.lang.Exception
  - write
```
public abstract void write(OutputT value)
                    throws java.lang.Exception
```
    Called for each value in the bundle.
    
    Throws:
    
    java.lang.Exception
  - getOutputFile
```
public ResourceId getOutputFile()
```
  - cleanup
```
public final void cleanup()
                   throws java.lang.Exception
```
    Throws:
    
    java.lang.Exception
  - close
```
public final void close()
                 throws java.lang.Exception
```
    Closes the channel and returns the bundle result.
    
    Throws:
    
    java.lang.Exception
  - getWriteOperation
```
public FileBasedSink.WriteOperation<DestinationT,OutputT> getWriteOperation()
```
    Return the WriteOperation that this Writer belongs to.
  - getDestination
```
public DestinationT getDestination()
```
    Return the user destination object for this writer.

Class FileBasedSink.Writer<DestinationT,​OutputT>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Writer

Method Detail

prepareWrite

writeHeader

writeFooter

finishWrite

open

write

getOutputFile

cleanup

close

getWriteOperation

getDestination

Class FileBasedSink.Writer<DestinationT,OutputT>