Saving file information in Spring batch MultiResourceItemReader - spring

Question

I have a directory having text files. I want to process files and write data into db. I did that by using MultiResourceItemReader.
I have a scenario like whenever file is coming, the first step is to save file info, like filename, record count in file in a log table(custom table).
Since i used MultiResourceItemReader, It's loading all files once and the code which i wrote is executing once in server startup. I tried with getCurrentResource() method but its returning null.
Please refer below code.
NetFileProcessController.java
#Slf4j
#RestController
#RequestMapping("/netProcess")
public class NetFileProcessController {
#Autowired
private JobLauncher jobLauncher;
#Autowired
#Qualifier("netFileParseJob")
private Job job;
#GetMapping(path = "/process")
public #ResponseBody StatusResponse process() throws ServiceException {
try {
Map<String, JobParameter> parameters = new HashMap<>();
parameters.put("date", new JobParameter(new Date()));
jobLauncher.run(job, new JobParameters(parameters));
return new StatusResponse(true);
} catch (Exception e) {
log.error("Exception", e);
Throwable rootException = ExceptionUtils.getRootCause(e);
String errMessage = rootException.getMessage();
log.info("Root cause is instance of JobInstanceAlreadyCompleteException --> "+(rootException instanceof JobInstanceAlreadyCompleteException));
if(rootException instanceof JobInstanceAlreadyCompleteException){
log.info(errMessage);
return new StatusResponse(false, "This job has been completed already!");
} else{
throw new ServiceException(errMessage);
}
}
}
}
BatchConfig.java
#Configuration
#EnableBatchProcessing
public class BatchConfig {
private JobBuilderFactory jobBuilderFactory;
#Autowired
public void setJobBuilderFactory(JobBuilderFactory jobBuilderFactory) {
this.jobBuilderFactory = jobBuilderFactory;
}
#Autowired
StepBuilderFactory stepBuilderFactory;
#Value("file:${input.files.location}${input.file.pattern}")
private Resource[] netFileInputs;
#Value("${net.file.column.names}")
private String netFilecolumnNames;
#Value("${net.file.column.lengths}")
private String netFileColumnLengths;
#Autowired
NetFileInfoTasklet netFileInfoTasklet;
#Autowired
NetFlatFileProcessor netFlatFileProcessor;
#Autowired
NetFlatFileWriter netFlatFileWriter;
#Bean
public Job netFileParseJob() {
return jobBuilderFactory.get("netFileParseJob")
.incrementer(new RunIdIncrementer())
.start(netFileStep())
.build();
}
public Step netFileStep() {
return stepBuilderFactory.get("netFileStep")
.<NetDetailsDTO, NetDetailsDTO>chunk(1)
.reader(new NetFlatFileReader(netFileInputs, netFilecolumnNames, netFileColumnLengths))
.processor(netFlatFileProcessor)
.writer(netFlatFileWriter)
.build();
}
}
NetFlatFileReader.java
#Slf4j
public class NetFlatFileReader extends MultiResourceItemReader<NetDetailsDTO> {
public netFlatFileReader(Resource[] netFileInputs, String netFilecolumnNames, String netFileColumnLengths) {
setResources(netFileInputs);
setDelegate(reader(netFilecolumnNames, netFileColumnLengths));
}
private FlatFileItemReader<NetDetailsDTO> reader(String netFilecolumnNames, String netFileColumnLengths) {
FlatFileItemReader<NetDetailsDTO> flatFileItemReader = new FlatFileItemReader<>();
FixedLengthTokenizer tokenizer = CommonUtil.fixedLengthTokenizer(netFilecolumnNames, netFileColumnLengths);
FieldSetMapper<NetDetailsDTO> mapper = createMapper();
DefaultLineMapper<NetDetailsDTO> lineMapper = new DefaultLineMapper<>();
lineMapper.setLineTokenizer(tokenizer);
lineMapper.setFieldSetMapper(mapper);
flatFileItemReader.setLineMapper(lineMapper);
return flatFileItemReader;
}
/*
* Mapping column data to DTO
*/
private FieldSetMapper<NetDetailsDTO> createMapper() {
BeanWrapperFieldSetMapper<NetDetailsDTO> mapper = new BeanWrapperFieldSetMapper<>();
try {
mapper.setTargetType(NetDetailsDTO.class);
} catch(Exception e) {
log.error("Exception in mapping column data to dto ", e);
}
return mapper;
}
}
I am stuck on this scenario, Any help appreciated

Answer 1

I don't think MultiResourceItemReader is appropriate in your case. I would run a job per file for all the reasons of making one thing do one thing and do it well:
Your preparatory step will work by design
It would be easier to run multiple jobs in parallel and improve your file ingestion throughput
In case of failure, you would only restart the job for the failed file
EDIT: add an example
Resource[] netFileInputs = ... // same code that looks for file as currently in your reader
for (Resource netFileInput : netFileInputs) {
Map<String, JobParameter> parameters = new HashMap<>();
parameters.put("netFileInput", new JobParameter(netFileInput.getFilename()));
jobLauncher.run(job, new JobParameters(parameters));
}