Popular Tutorials • • • • • • • • • • • • 1. ItemReader ItemReader is the means for providing data from many different types of input. ItemReader interface is the means for reading bulk data in a bulk processing system. There are many different implementations of ItemReader interface. All implementations are expected to be stateful and will be called multiple times for each batch, with each call to read() returning a different value and finally returning null when all input data is exhausted. Below are few frequently used implementations of ItemReader. ItemReader Implementation Description FlatFileItemReader Reads lines of data from input file.

Typically read line describe records with fields of data defined by fixed positions in the file or delimited by some special character (e.g. Comma (,), Pipe ( ) etc). JdbcCursorItemReader Opens a JDBC cursor and continually retrieves the next row in the ResultSet. StoredProcedureItemReader Executes a stored procedure and then reads the returned cursor and continually retrieves the next row in the ResultSet.

All the above implementations override the read() method from the ItemReader interface. The read method defines the most essential contract of the ItemReader. It returns one item or null if no more items are left. An item might represent a line in a file, a row in a database and so on.

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ItemWriter ItemWriter is similar in functionality to an ItemReader, but with inverse operations. ItemWriter is a interface for generic output operations. Implementation class will be responsible for serializing objects as necessary. Resources still need to be located, opened and closed but they differ in that an ItemWriter writes out, rather than reading in. For databases these may be inserts or updates. The write method defines the most essential contract of the ItemWriter.

It will attempt to write out the list of items passed in as long as it is open. As it is expected that items will be ‘batched’ together into a chunk and then output, the interface accepts a list of items, rather than an item by itself. Download Film Hot Korea Lies. Once the items are written out, any flushing that may be necessary can be performed before returning from the write method.