How to use ClassifierCompositeItemProcessor in Spring Batch and write data into same table for Insert and Upsert? - spring

Question

I went through the link - https://github.com/spring-projects/spring-batch/blob/master/spring-batch-infrastructure/src/test/java/org/springframework/batch/item/support/ClassifierCompositeItemProcessorTests.java, but did not strike much out of it.
I am trying to replace ETL Informatica mapping logic into the Batch. I am looking to separate out Status=I and Status=U into separate (Individual) processor and then further perform lookup and massage the data and then write those records directly into the table for Status=I and for status=U, perform another complex logic (like lookups, massaging and match and merge logic) and then upsert those records again into the same table.
I've tried to do POC, where I am looking to segregate the records in the processor
CustomerClassifier.java
public class CustomerClassifier implements Classifier<Customer, ItemProcessor<Customer, Customer>> {
private ItemProcessor<Customer, Customer> insertCustomerProcessor;
private ItemProcessor<Customer, Customer> updateCustomerProcessor;
public CustomerClassifier(ItemProcessor<Customer, Customer> evenCustomerProcessor, ItemProcessor<Customer, Customer> oddCustomerProcessor) {
this.insertCustomerProcessor= insertCustomerProcessor;
this.updateCustomerProcessor= updateCustomerProcessor;
}
#Override
public ItemProcessor<Customer, Customer> classify(Customer customer) {
return customer.getStatus().equals("I") ? insertCustomerProcessor : updateCustomerProcessor;
}
}
OddCustomerProcessor.java
public class OddCustomerProcessor implements ItemProcessor<Customer, Customer> {
#Override
public Customer process(Customer item) throws Exception {
Customer customer = new Customer();
// Perform some msaaging and lookups here
customer.setId(item.getId());
customer.setFirstName(item.getFirstName());
customer.setLastName(item.getLastName());
customer.setBirthdate(item.getBirthdate());
customer.setStatus(item.getStatus());
return customer;
}
}
EvenCustomerProcessor.java
public class EvenCustomerProcessor implements ItemProcessor<Customer, Customer> {
#Override
public Customer process(Customer item) throws Exception {
Customer customer = new Customer();
// Perform some msaaging and lookups here
customer.setId(item.getId());
customer.setFirstName(item.getFirstName());
customer.setLastName(item.getLastName());
customer.setBirthdate(item.getBirthdate());
customer.setStatus(item.getStatus());
return customer;
}
}
CustomLineAggregator.java
public class CustomLineAggregator implements LineAggregator<Customer> {
private ObjectMapper objectMapper = new ObjectMapper();
#Override
public String aggregate(Customer item) {
try {
return objectMapper.writeValueAsString(item);
} catch (Exception e) {
throw new RuntimeException("Unable to serialize Customer", e);
}
}
}
Customer.java
#Data
#AllArgsConstructor
#Builder
#NoArgsConstructor
public class Customer {
private Long id;
private String firstName;
private String lastName;
private String birthdate;
private String status;
}
Error-
The method setClassifier(Classifier<? super Customer,ItemProcessor<?,? extends Customer>>) in the type ClassifierCompositeItemProcessor<Customer,Customer> is not applicable for the
arguments (CustomerClassifier)
Configuration
#Configuration
public class JobConfiguration {
#Autowired
private JobBuilderFactory jobBuilderFactory;
#Autowired
private StepBuilderFactory stepBuilderFactory;
#Autowired
private DataSource dataSource;
#Bean
public JdbcPagingItemReader<Customer> customerPagingItemReader(){
// reading database records using JDBC in a paging fashion
JdbcPagingItemReader<Customer> reader = new JdbcPagingItemReader<>();
reader.setDataSource(this.dataSource);
reader.setFetchSize(1000);
reader.setRowMapper(new CustomerRowMapper());
// Sort Keys
Map<String, Order> sortKeys = new HashMap<>();
sortKeys.put("id", Order.ASCENDING);
// MySQL implementation of a PagingQueryProvider using database specific features.
MySqlPagingQueryProvider queryProvider = new MySqlPagingQueryProvider();
queryProvider.setSelectClause("id, firstName, lastName, birthdate");
queryProvider.setFromClause("from customer");
queryProvider.setSortKeys(sortKeys);
reader.setQueryProvider(queryProvider);
return reader;
}
#Bean
public EvenCustomerProcessor evenCustomerProcessor() {
return new EvenCustomerProcessor();
}
#Bean
public OddCustomerProcessor oddCustomerProcessor() {
return new OddCustomerProcessor();
}
#Bean
public JdbcBatchItemWriter<Customer> customerItemWriter(){
JdbcBatchItemWriter<Customer> batchItemWriter = new JdbcBatchItemWriter<>();
batchItemWriter.setDataSource(dataSource);
batchItemWriter.setSql(""); // Query Goes here
return batchItemWriter;
}
#Bean
public ClassifierCompositeItemProcessor<Customer, Customer> classifierCustomerCompositeItemProcessor() throws Exception{
ClassifierCompositeItemProcessor<Customer, Customer> itemProcessor = new ClassifierCompositeItemProcessor<>();
itemProcessor.setClassifier(new CustomerClassifier(evenCustomerProcessor(), oddCustomerProcessor()));
}
#Bean
public Step step1() throws Exception {
return stepBuilderFactory.get("step1")
.<Customer, Customer> chunk(10)
.reader(customerPagingItemReader())
.processor(classifierCustomerCompositeItemProcessor())
.writer(customerItemWriter())
.build();
}
#Bean
public Job job() throws Exception {
return jobBuilderFactory.get("job")
.start(step1())
.build();
}
}

Answer 1

You can remove the CustomerClassifier and define the composite item processor as follows:
#Bean
public ClassifierCompositeItemProcessor<Customer, Customer> classifierCustomerCompositeItemProcessor(
EvenCustomerProcessor evenCustomerProcessor,
OddCustomerProcessor oddCustomerProcessor
) {
ClassifierCompositeItemProcessor<Customer, Customer> itemProcessor = new ClassifierCompositeItemProcessor<>();
itemProcessor.setClassifier(new Classifier<Customer, ItemProcessor<?, ? extends Customer>>() {
#Override
public ItemProcessor<?, ? extends Customer> classify(Customer customer) {
return customer.getStatus().equals("I") ? evenCustomerProcessor : oddCustomerProcessor;
}
});
return itemProcessor;
}
Then update your step definition as follows:
#Bean
public Step step1() throws Exception {
return stepBuilderFactory.get("step1")
.<Customer, Customer> chunk(10)
.reader(customerPagingItemReader())
.processor(classifierCustomerCompositeItemProcessor(evenCustomerProcessor(), oddCustomerProcessor()))
.writer(customerItemWriter())
.build();
}