Json Array reader file with spring batch

Question

I have a file as an input which contain a json Array :

[ {
  ...,
  ...
  },
  {
  ...,
  ...
  },
  {
  ...,
  ...
  }
]

I want to read

Answer 1

Assuming you want to model the StaxEventItemReader in that you want to read each item of the JSON array as an item in Spring Batch, here's what I'd recommend:

• RecordSeparatorPolicy - You'll need to implement your own RecordSepartorPolicy that indicates if you've finished reading in the full item or not. You can also use the RecordSeparatoerPolicy#postProcess to cleanup the beginning and ending [] you'll need to deal with as well as the comma delimiters.

• LineTokenizer - You'll then want to create your own LineTokenzier that parses JSON. I was just working on one today for a project so you can use that code as a start (consider it untested):

  public class JsonLineTokenizer implements LineTokenizer {
  
      @Override
      public FieldSet tokenize(String line) {
          List tokens = new ArrayList<>();
  
          try {
              HashMap result =
                      new ObjectMapper().readValue(line, HashMap.class);
  
              tokens.add((String) result.get("field1"));
              tokens.add((String) result.get("field2")));
  
          } catch (IOException e) {
              throw new RuntimeException("Unable to parse json: " + line);
          }
  
          return new DefaultFieldSet(tokens.toArray(new String[0]), {"field1", "field2"});
      }
  }