Batch file renaming java tool class

Write a java tool class that supports batch modification of the names of files and folders in the specified directory according to the number. For example: the numbers are 10001, 30541... According to the code and name matching table, the file names are modified in batches as Zhang San, Li Si.... Reduce tedious manual operations.
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 package com.zp.myjavademo.filecollection;

import com.alibaba.fastjson.JSON;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

/**
 * author : zp
 * e-mail : zhangping1
 * time : 2019-08-29 13:17
 * desc :遍历文件目录，根据原文件名的客户号匹配json中客户姓名进行重命名
 * version: 1.0
 */
public class FileUtils {

    private static String jsonStr;
    private static FileNameBean bean = new FileNameBean();

    private static String jsonPathDir = "/Users/theappleofna/workspace/android_demo/MyTestCollection/MyJavaDemo/src/main/java/com/zp/myjavademo/filecollection/filename.json";
    private static String filePathDir = "/Users/theappleofna/workspace/test/files/";

    public static void main(String[] args) throws IOException {

        // 从目录读取json文件
        jsonStr = readJsonData(jsonPathDir);
//        System.out.println("得到当前路径json===" + jsonStr);

        // 解析。将匹配关系解析道json实体类
        bean = JSON.parseObject(jsonStr, FileNameBean.class);

        // 遍历得到所有文件数组
        File file = new File(filePathDir);
        String[] fileNameList = file.list();
        System.out.println("读取文件列表---" + Arrays.toString(fileNameList));

        // 进性重命名
        renameFile(fileNameList);
    }

    /**
     * 遍历文件目录，根据原文件名的客户号匹配json中客户姓名进性重命名
     *
     * @param fileName
     * @author zhangping
     */
    private static void renameFile(String[] fileName) {
        for (int i = 0; i < fileName.length; i++) {
            System.out.println("源文件名==" + fileName[i]);

            for (int n = 0; n < bean.getData().size(); n++) {
                if (bean.getData().get(n).getUSERSEQ().equals(fileName[i])) {
                    System.out.println("该客户索引==" + n);

                    File oldFileName = new File(filePathDir + fileName[i]);
                    File newFileName = new File(filePathDir + bean.getData().get(n).getCIFNAME() + "影像资料");
                    System.out.println("oldName===" + oldFileName + "\n newFileName==" + newFileName);

                    if (oldFileName.renameTo(newFileName)) {
                        System.out.println("重命名成功~~");
                    } else {
                        System.out.println("重命名失败!!!");
                    }
                }
            }
        }
    }

    public static String readJsonData(String pactFile) throws IOException {

        StringBuffer strbuffer = new StringBuffer();
        File myFile = new File(pactFile);// "D:"+File.separatorChar+"DStores.json"
        if (!myFile.exists()) {
            System.err.println("Can't Find " + pactFile);
        }
        try {
            FileInputStream fis = new FileInputStream(pactFile);
            InputStreamReader inputStreamReader = new InputStreamReader(fis, "UTF-8");
            BufferedReader in = new BufferedReader(inputStreamReader);

            String str;
            while ((str = in.readLine()) != null) {
                strbuffer.append(str); // new String(str,"UTF-8")
            }
            in.close();
        } catch (IOException e) {
            e.getStackTrace();
        }
        // System.out.println("读取文件结束util");
        return strbuffer.toString();
    }
}