java/project/main/java/com/example/export/CsvExporter.java

package com.example.export;

import java.io.FileWriter;
import java.io.PrintWriter;
import java.lang.reflect.Field;
import java.util.List;

public class CsvExporter<T> implements Exporter<T> {
    private static final String CSV_SEPARATOR = ",";

    @Override
    public void export(List<T> data, String filePath) {
        if (data == null || data.isEmpty()) {
            throw new IllegalArgumentException("数据不能为空");
        }

        try (PrintWriter writer = new PrintWriter(new FileWriter(filePath))) {
            T firstItem = data.get(0);
            writer.println(getHeader(firstItem.getClass()));
            
            for (T item : data) {
                writer.println(toCsvRow(item));
            }
            System.out.println("数据已导出到CSV文件: " + filePath);
        } catch (Exception e) {
            throw new RuntimeException("CSV导出失败: " + e.getMessage(), e);
        }
    }

    private String getHeader(Class<?> clazz) {
        StringBuilder header = new StringBuilder();
        Field[] fields = clazz.getDeclaredFields();
        for (int i = 0; i < fields.length; i++) {
            if (i > 0) header.append(CSV_SEPARATOR);
            header.append(fields[i].getName());
        }
        return header.toString();
    }

    private String toCsvRow(T item) {
        StringBuilder row = new StringBuilder();
        Field[] fields = item.getClass().getDeclaredFields();
        try {
            for (int i = 0; i < fields.length; i++) {
                if (i > 0) row.append(CSV_SEPARATOR);
                fields[i].setAccessible(true);
                Object value = fields[i].get(item);
                row.append(value != null ? value.toString() : "");
            }
        } catch (Exception e) {
            throw new RuntimeException("CSV行转换失败: " + e.getMessage(), e);
        }
        return row.toString();
    }

    @Override
    public String getFormat() {
        return "CSV";
    }
}