Spring Batch - read date field as a String in readers and convert it to other format

Question

Before posting the question, I went through many links like: Using Spring Batch to parse date from file into LocalDateTime and Spring Batch - how to convert String from file to Date? etc but that doesn't solve my problem.

In my project I'm reading csv file and creating one more csv out of it for the target system the way they want.

Source csv file has many fields and values like Apr 1 2022 12:00:00:000AM which is clearly a dateformat and I am reading this as String and while reading I want to convert it into yyyyMMdd format with the String value, so all values in my model class in String

<bean id="flatFileItemReader" class="org.springframework.batch.item.file.FlatFileItemReader">
        <property name="lineMapper">
            <bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
                <property name="lineTokenizer">
                    <bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
                        <property name="delimiter">
                            <util:constant static-field="org.springframework.batch.item.file.transform.DelimitedLineTokenizer.DELIMITER_TAB" />
                        </property>
                        <property name="names" value="field1, field2...... field60" />
                    </bean>
                </property>
                <property name="fieldSetMapper">
                    <bean class="XX.XX.XX.XX.MyBeanWrapperFieldSetMapper">
                        <property name="targetType" value="com.xxxxx.SomeModel" />
                        <property name="customEditors" value="" />
                    </bean>
                </property>
            </bean>
        </property>
    </bean>

Other code

public class MyBeanWrapperFieldSetMapper<T> extends BeanWrapperFieldSetMapper<T> {
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMM  d yyyy hh:mm:ss:SSSa", Locale.US);

    @Override
    protected void initBinder(DataBinder binder) {
        binder.registerCustomEditor(LocalDate.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) throws IllegalArgumentException {
                if (StringUtils.isNotEmpty(text)) {
                    setValue(LocalDate.parse(text, formatter));
                } else {
                    setValue(null);
                }
            }

            @Override
            public String getAsText() throws IllegalArgumentException {
                Object date = getValue();
                if (date != null) {
                    return formatter.format((LocalDate) date);
                } else {
                    return "";
                }
            }
        });
    }
}

Model

@AllArgsConstructor
@NoArgsConstructor
@Builder
@Data
public class SomeModel {
    private String id;
    private String createdDt;
    private String repliedDt;
    ....
    ...
}

Answer 1

I was able to solve this by using solution like this (The solution shown for another example)

<bean id="flatFileItemReader" class="org.springframework.batch.item.file.FlatFileItemReader" scope="step">
        <property name="resource" value="classpath:employee.csv" />
        <property name="linesToSkip" value="1" />
        <property name="lineMapper">
            <bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
                <property name="fieldSetMapper">
                    <!-- Mapper which maps each individual items in a record to properties in POJO -->
                    <bean class="com.example.EmployeeFieldSetMapper" />
                </property>
                <property name="lineTokenizer">
                    <!-- A tokenizer class to be used when items in input record are separated by specific characters -->
                    <bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
                        <property name="delimiter" value=","/>
                        <property name="names" value="empId,firstName,lastName,age,email,joiningDate" />
                    </bean>
                </property>
            </bean>
        </property>
    </bean>

FieldSetMapper

public class EmployeeFieldSetMapper implements FieldSetMapper<Employee> {
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMM  d yyyy hh:mm:ss:SSSa", Locale.US);
    DateTimeFormatter NEW_FORMAT = DateTimeFormatter.ofPattern("yyyyMMdd", Locale.US);

    @Override
    public Employee mapFieldSet(FieldSet fieldSet) throws BindException {
        String joiningDate = fieldSet.readRawString("joiningDate");
        return Employee.builder()
                .empId(fieldSet.readLong("empId"))
                .firstName(fieldSet.readString("firstName"))
                .lastName(fieldSet.readString("lastName"))
                .age(fieldSet.readInt("age"))
                .email(fieldSet.readString("email"))
                .joiningDate(joiningDate != null ?  formatFDate(joiningDate) : null)
                .build();
    }

    private String formatFDate(String value){
        LocalDateTime dateTime = LocalDateTime.parse(value, formatter);
        return dateTime.format(NEW_FORMAT);
    }
}