CODEWITHSUNDEEP
javacsvspring-batch
Hamza Ince
Hamza Ince

Reputation: 684

Use FlatFileItemReader to read a List of elements

Let's say, I have an object Engine, the only attribute is brandName, I then have a CSV file as below:

car_brand; bike_brand; airplane_brand; boat_brand
brand1;    brand2;     brand3;         brand4
brand5;    brand6;     brand7;         brand8
brand9;    brand10;    brand11;        brand12

What I want to do, is reading the CSV file and creating a List for each row.

Since my project is a Spring batch project, I want to use a Reader, but how can I do it?

I tried to do:

@Bean
public FlatFileItemReader<Engine> reader() {
    FlatFileItemReader<Engine> reader = new FlatFileItemReader<Project>();
    reader.setResource(new ClassPathResource("file.csv"));
    reader.setLinesToSkip(1);
    reader.setLineMapper(new DefaultLineMapper<Project>() {
        {
            setLineTokenizer(new DelimitedLineTokenizer() {
                {
                    setNames(***);
                }
            });
            setFieldSetMapper(new BeanWrapperFieldSetMapper<Project>() {
                {
                    setTargetType(Engine.class);
                }
            });
        }
    });
    return reader;
}

Usually you create only one object with the reader, how can I create List with the Reader?
Should I change the method type to < List< Engine>>?

EDIT: My question is not how to make a Reader of a List, but how to make a FlatFileItemReader of a List, the duplicate question is not the answer I needed.

Upvotes: 1

Views: 2961

Answers (1)

i.bondarenko
i.bondarenko

Reputation: 3572

You could try following:

@Bean
LineMapper<List<Engine>> lineMapper() {
    return new LineMapper<List<Engine>>() {
        @Override
        public <List<Engine>> mapLine(String line, int lineNum) throws Exception {
            String[] tokens = line.split(";");
            if (tokens.length < 1) {
                throw new DataIntegrityViolationException("Expecting at least one token in input line: " + line);
            }
            List<Engine> data = new ArrayList<Engine>;
            for (String token : tokens) {
                data.add(Engine.of(token));
            }
            return data;
        }
    };
}

....

FlatFileItemReader<List<Engine>> itemReader = new FlatFileItemReader<>();
        itemReader.setLineMapper(lineMapper);

Upvotes: 1

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