OpenCSV解析自定义逻辑：入职日期校验与CSVException抛出需求

Got it, let's walk through how to add that custom date range validation to your OpenCSV parsing workflow. Here's a step-by-step solution that fits your needs:

We'll implement a custom bean verifier to check if firstDayOfWork is earlier than lastDayOfWork, and collect any validation failures as CSVExceptions during parsing.

1. Define Your CSV Entity Class #

First, create a POJO to map your CSV fields, including date fields with proper formatting annotations:

import com.opencsv.bean.CsvBindByName;
import org.springframework.format.annotation.DateTimeFormat;
import java.math.BigDecimal;
import java.time.LocalDate;

public class Employee {
    @CsvBindByName(column = "firstName")
    private String firstName;
    
    @CsvBindByName(column = "secondName")
    private String secondName;
    
    @CsvBindByName(column = "firstSalary")
    private BigDecimal firstSalary;
    
    @CsvBindByName(column = "lastSalary")
    private BigDecimal lastSalary;
    
    @CsvBindByName(column = "firstDayOfWork")
    @DateTimeFormat(pattern = "yyyy-MM-dd") // Adjust to match your CSV date format
    private LocalDate firstDayOfWork;
    
    @CsvBindByName(column = "lastDayOfWork")
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    private LocalDate lastDayOfWork;
    
    // Getters and setters for all fields
}

2. Create a Custom Bean Verifier #

Implement OpenCSV's BeanVerifier interface to add your date range check. This verifier will throw a CsvValidationException if the date condition isn't met:

import com.opencsv.bean.BeanVerifier;
import com.opencsv.exceptions.CsvValidationException;
import java.time.LocalDate;

public class EmployeeDateRangeVerifier implements BeanVerifier<Employee> {
    @Override
    public boolean verifyBean(Employee employee) throws CsvValidationException {
        LocalDate startDate = employee.getFirstDayOfWork();
        LocalDate endDate = employee.getLastDayOfWork();
        
        // Validate both dates exist and start is before end
        if (startDate != null && endDate != null && !startDate.isBefore(endDate)) {
            throw new CsvValidationException(
                String.format("Invalid date range for %s %s: firstDayOfWork (%s) is not earlier than lastDayOfWork (%s)",
                    employee.getFirstName(), employee.getSecondName(), startDate, endDate)
            );
        }
        return true;
    }
}

3. Parse CSV with Custom Validation #

Configure your CsvToBean instance to use the verifier, and enable exception capturing to collect all validation errors instead of stopping at the first failure:

import com.opencsv.bean.CsvToBean;
import com.opencsv.bean.CsvToBeanBuilder;
import com.opencsv.exceptions.CsvException;
import java.io.FileReader;
import java.util.List;

public class CsvParser {
    public static void main(String[] args) {
        try (FileReader reader = new FileReader("your-employees.csv")) {
            CsvToBean<Employee> csvParser = new CsvToBeanBuilder<Employee>(reader)
                .withType(Employee.class)
                .withVerifier(new EmployeeDateRangeVerifier()) // Attach your custom verifier
                .withThrowExceptions(false) // Critical: Collects all exceptions instead of halting early
                .build();
            
            // Parse valid records
            List<Employee> validEmployees = csvParser.parse();
            // Retrieve all validation exceptions
            List<CsvException> validationErrors = csvParser.getCapturedExceptions();
            
            // Handle the errors
            if (!validationErrors.isEmpty()) {
                System.out.println("Parsing encountered validation errors:");
                for (CsvException error : validationErrors) {
                    System.out.printf("Line %d: %s%n", error.getLineNumber(), error.getMessage());
                }
            }
            
            // Process your valid employee records here
            // ...
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Key Tips #

• Date Format Matching: Ensure the @DateTimeFormat pattern exactly matches the date format in your CSV (e.g., use "MM/dd/yyyy" if your dates are formatted that way).
• Null Handling: The verifier checks for null dates to avoid NullPointerExceptions—adjust this logic if your CSV guarantees these fields are always populated.
• Exception Capturing: withThrowExceptions(false) is mandatory if you want to collect all validation errors; without it, parsing stops at the first invalid record.

内容的提问来源于stack exchange，提问作者Poppo Pippo