java文件合并帮助诶

package com.longgeutil;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.channels.FileChannel;
import java.util.List;

import org.apache.commons.lang3.StringUtils;
import org.springframework.util.CollectionUtils;

import lombok.extern.slf4j.Slf4j;

/**
 * 
 * @author roger yang
 * @date 11/04/2019
 */
@Slf4j
public class FileUtils {    
    public static boolean mergeFiles(List<String> fpaths, String resultPath) {
        if (CollectionUtils.isEmpty(fpaths) || StringUtils.isEmpty(resultPath)) {
            return false;
        }
        if (fpaths.size() == 1) {
            return new File(fpaths.get(0)).renameTo(new File(resultPath));
        }

        File[] files = new File[fpaths.size()];
        for (int i = 0; i < fpaths.size(); i++) {
            if (StringUtils.isEmpty(fpaths.get(i))) {
                return false;
            }

            files[i] = new File(fpaths.get(i));
            if (!files[i].exists() || !files[i].isFile()) {
                return false;
            }
        }

        File resultFile = new File(resultPath);

        try (FileOutputStream os = new FileOutputStream(resultFile, true);
            FileChannel resultFileChannel = os.getChannel();) {
            for (int i = 0; i < fpaths.size(); i++) {
                try (FileChannel blk = new FileInputStream(files[i]).getChannel();) {
                    resultFileChannel.transferFrom(blk, resultFileChannel.size(), blk.size());
                }
            }
        } catch (Exception e) {
            log.error("merge file error", e);
            return false;
        }

        for (int i = 0; i < fpaths.size(); i++) {
            files[i].delete();
        }

        return true;
    }
}