如何用Java解析一个固定宽度的文件？

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class FixedWidthFileParser {
    public static void main(String[] args) {
        String filePath = "path/to/file.txt";
        int[] fieldWidths = {10, 20, 15};

        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = reader.readLine()) != null) {
                String[] fields = parseFixedWidthFields(line, fieldWidths);
                // 处理每个字段的数据
                // ...
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static String[] parseFixedWidthFields(String line, int[] fieldWidths) {
        String[] fields = new String[fieldWidths.length];
        int startPos = 0;
        for (int i = 0; i < fieldWidths.length; i++) {
            int endPos = startPos + fieldWidths[i];
            fields[i] = line.substring(startPos, endPos).trim();
            startPos = endPos;
        }
        return fields;
    }
}