Java如何编写一个文件处理工具类FileUtils呢?

此工具类包含以下内容:
    文件转字节
	文件删除
	字节写入到文件
	检测文件是否可下载
	检测文件名是否合规
	MultipartFile转换为File
	File转Base64编码
	复制zip压缩文件

package com.java265.common.utils.file;
 
import java.io.*;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.ArrayUtils;
import com.java265.common.config.RuoYiConfig;
import com.java265.common.utils.DateUtils;
import com.java265.common.utils.StringUtils;
import com.java265.common.utils.uuid.IdUtils;
import org.apache.commons.io.FilenameUtils;
import org.springframework.http.MediaType;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
 
/**
 * 文件处理工具类 
 */
public class FileUtils
{
    public static String FILENAME_PATTERN = "[a-zA-Z0-9_\\-\\|\\.\\u4e00-\\u9fa5]+";
 
    /**
     * 输出指定文件的byte数组
     * 
     * @param filePath 文件路径
     * @param os 输出流
     * @return
     */
    public static void writeBytes(String filePath, OutputStream os) throws IOException
    {
        FileInputStream fis = null;
        try
        {
            File file = new File(filePath);
            if (!file.exists())
            {
                throw new FileNotFoundException(filePath);
            }
            fis = new FileInputStream(file);
            byte[] b = new byte[1024];
            int length;
            while ((length = fis.read(b)) > 0)
            {
                os.write(b, 0, length);
            }
        }
        catch (IOException e)
        {
            throw e;
        }
        finally
        {
            IOUtils.close(os);
            IOUtils.close(fis);
        }
    }
 
    /**
     * 写数据到文件中
     *
     * @param data 数据
     * @return 目标文件
     * @throws IOException IO异常
     */
    public static String writeImportBytes(byte[] data) throws IOException
    {
        return writeBytes(data, RuoYiConfig.getImportPath());
    }
 
    /**
     * 写数据到文件中
     *
     * @param data 数据
     * @param uploadDir 目标文件
     * @return 目标文件
     * @throws IOException IO异常
     */
    public static String writeBytes(byte[] data, String uploadDir) throws IOException
    {
        FileOutputStream fos = null;
        String pathName = "";
        try
        {
            String extension = getFileExtendName(data);
            pathName = DateUtils.datePath() + "/" + IdUtils.fastUUID() + "." + extension;
            File file = FileUploadUtils.getAbsoluteFile(uploadDir, pathName);
            fos = new FileOutputStream(file);
            fos.write(data);
        }
        finally
        {
            IOUtils.close(fos);
        }
        return FileUploadUtils.getPathFileName(uploadDir, pathName);
    }
 
    /**
     * 删除文件
     * 
     * @param filePath 文件
     * @return
     */
    public static boolean deleteFile(String filePath)
    {
        boolean flag = false;
        File file = new File(filePath);
        // 路径为文件且不为空则进行删除
        if (file.isFile() && file.exists())
        {
            file.delete();
            flag = true;
        }
        return flag;
    }
 
    /**
     * 文件名称验证
     * 
     * @param filename 文件名称
     * @return true 正常 false 非法
     */
    public static boolean isValidFilename(String filename)
    {
        return filename.matches(FILENAME_PATTERN);
    }
 
    /**
     * 检查文件是否可下载
     * 
     * @param resource 需要下载的文件
     * @return true 正常 false 非法
     */
    public static boolean checkAllowDownload(String resource)
    {
        // 禁止目录上跳级别
        if (StringUtils.contains(resource, ".."))
        {
            return false;
        }
 
        // 检查允许下载的文件规则
        if (ArrayUtils.contains(MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION, FileTypeUtils.getFileType(resource)))
        {
            return true;
        }
 
        // 不在允许下载的文件规则
        return false;
    }
 
    /**
     * 下载文件名重新编码
     * 
     * @param request 请求对象
     * @param fileName 文件名
     * @return 编码后的文件名
     */
    public static String setFileDownloadHeader(HttpServletRequest request, String fileName) throws UnsupportedEncodingException
    {
        final String agent = request.getHeader("USER-AGENT");
        String filename = fileName;
        if (agent.contains("MSIE"))
        {
            // IE浏览器
            filename = URLEncoder.encode(filename, "utf-8");
            filename = filename.replace("+", " ");
        }
        else if (agent.contains("Firefox"))
        {
            // 火狐浏览器
            filename = new String(fileName.getBytes(), "ISO8859-1");
        }
        else if (agent.contains("Chrome"))
        {
            // google浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }
        else
        {
            // 其它浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }
        return filename;
    }
 
    /**
     * 下载文件名重新编码
     *
     * @param response 响应对象
     * @param realFileName 真实文件名
     */
    public static void setAttachmentResponseHeader(HttpServletResponse response, String realFileName) throws UnsupportedEncodingException
    {
        String percentEncodedFileName = percentEncode(realFileName);
 
        StringBuilder contentDispositionValue = new StringBuilder();
        contentDispositionValue.append("attachment; filename=")
                .append(percentEncodedFileName)
                .append(";")
                .append("filename*=")
                .append("utf-8''")
                .append(percentEncodedFileName);
 
        response.addHeader("Access-Control-Expose-Headers", "Content-Disposition,download-filename");
        response.setHeader("Content-disposition", contentDispositionValue.toString());
        response.setHeader("download-filename", percentEncodedFileName);
    }
 
    /**
     * 百分号编码工具方法
     *
     * @param s 需要百分号编码的字符串
     * @return 百分号编码后的字符串
     */
    public static String percentEncode(String s) throws UnsupportedEncodingException
    {
        String encode = URLEncoder.encode(s, StandardCharsets.UTF_8.toString());
        return encode.replaceAll("\\+", "%20");
    }
 
    /**
     * 获取图像后缀
     * 
     * @param photoByte 图像数据
     * @return 后缀名
     */
    public static String getFileExtendName(byte[] photoByte)
    {
        String strFileExtendName = "jpg";
        if ((photoByte[0] == 71) && (photoByte[1] == 73) && (photoByte[2] == 70) && (photoByte[3] == 56)
                && ((photoByte[4] == 55) || (photoByte[4] == 57)) && (photoByte[5] == 97))
        {
            strFileExtendName = "gif";
        }
        else if ((photoByte[6] == 74) && (photoByte[7] == 70) && (photoByte[8] == 73) && (photoByte[9] == 70))
        {
            strFileExtendName = "jpg";
        }
        else if ((photoByte[0] == 66) && (photoByte[1] == 77))
        {
            strFileExtendName = "bmp";
        }
        else if ((photoByte[1] == 80) && (photoByte[2] == 78) && (photoByte[3] == 71))
        {
            strFileExtendName = "png";
        }
        return strFileExtendName;
    }
 
    /**
     * 获取文件名称 /profile/upload/2022/04/16/ruoyi.png -- ruoyi.png
     * 
     * @param fileName 路径名称
     * @return 没有文件路径的名称
     */
    public static String getName(String fileName)
    {
        if (fileName == null)
        {
            return null;
        }
        int lastUnixPos = fileName.lastIndexOf('/');
        int lastWindowsPos = fileName.lastIndexOf('\\');
        int index = Math.max(lastUnixPos, lastWindowsPos);
        return fileName.substring(index + 1);
    }
 
    /**
     * 获取不带后缀文件名称 /profile/upload/2022/04/16/ruoyi.png -- ruoyi
     * 
     * @param fileName 路径名称
     * @return 没有文件路径和后缀的名称
     */
    public static String getNameNotSuffix(String fileName)
    {
        if (fileName == null)
        {
            return null;
        }
        String baseName = FilenameUtils.getBaseName(fileName);
        return baseName;
    }
 
    //File转MultipartFile
    public static MultipartFile getMultipartFile(File file) {
        FileItem item = new DiskFileItemFactory().createItem("file"
                , MediaType.MULTIPART_FORM_DATA_VALUE
                , true
                , file.getName());
        try (InputStream input = new FileInputStream(file);
             OutputStream os = item.getOutputStream()) {
            // 流转移
            IOUtils.copy(input, os);
        } catch (Exception e) {
            throw new IllegalArgumentException("Invalid file: " + e, e);
        }
 
        return new CommonsMultipartFile(item);
    }
 
    //路径校验不存在就创建对应的目录
    public static void filePath(String path){
        File file = new File(path);
        // 判断路径是否存在，不存在创建
        if (!file.exists()) {
            file.mkdirs();
        }
    }
 
    /**
     * 复制 文件或者文件夹
     * @param oldPath
     * @param newPath
     * @throws IOException
     */
    public static void  copyFile(String oldPath ,String newPath ){
        System.out.println("copy file from [" + oldPath + "] to [" + newPath +"]");
 
        try {
            File oldFile = new File(oldPath) ;
            if  (oldFile.exists())  {
 
                if(oldFile.isDirectory()){ // 如果是文件夹
                    File newPathDir = new File(newPath);
                    newPathDir.mkdirs();
                    File[] lists = oldFile.listFiles() ;
                    if(lists != null && lists.length > 0 ){
                        for (File file : lists) {
                            copyFile(file.getAbsolutePath(), newPath.endsWith(File.separator) ? newPath + file.getName() : newPath + File.separator + file.getName()) ;
                        }
                    }
                }else {
                    InputStream  inStream  =  new  FileInputStream(oldFile);  //读入原文件
                    FileOutputStream  fs  =  new  FileOutputStream(newPath);
                    write2Out(inStream ,fs) ;
                    inStream.close();
                }
            }
        }catch (Exception e){
            System.out.println("复制文件到新路径失败："+e.getMessage());
        }
    }
 
    public static void copeZipFile(String oldPath ,String newPath) throws Exception {
        FileInputStream fin = new FileInputStream(new File(oldPath));
        ZipInputStream zin = new ZipInputStream(fin);
        byte[] in_bytes = new byte[1000];
        zin.read(in_bytes,0,1000);
 
 
        FileOutputStream fout = new FileOutputStream(new File(newPath));
        ZipOutputStream zout = new ZipOutputStream(fout);
        zout.write(in_bytes,0,in_bytes.length);
 
        fin.close();
        zin.close();
        fout.close();
        zout.close();
    }
 
    /**
     *
     *
     * @param url     指定文件的位置
     * @param content    异常输出的内容
     * @throws Exception
     */
 
    public static void writeFile(String url, String content) throws Exception {
        File file = new File(url);
        FileWriter fw = null;
 
        //文件不存在创建新文件
        if (!file.exists()) {
            file.createNewFile();
        }else{
            FileUtils.deleteFile(url);
            file.createNewFile();
        }
        String writeDate = content;
        try {
            fw = new FileWriter(file, true);
            fw.write(writeDate + "\r\n");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fw != null) {
                fw.close();
            }
        }
 
    }
 
    /**
     * 重命名文件
     * @param file
     * @param name
     * @return
     */
    public static File renameFile(File file , String name ){
        String fileName = file.getParent()  + File.separator + name ;
        File dest = new File(fileName);
        file.renameTo(dest) ;
        return dest ;
    }
 
    private static void write2Out(InputStream input , OutputStream out) throws IOException {
        byte[] b = new byte[1024];
        int c = 0 ;
        while ( (c = input.read(b)) != -1 ) {
            out.write(b,0,c);
            out.flush();
        }
        out.flush();
    }
 
    /**
     * File转MultipartFile
     * @param file
     * @return
     */
    public static MultipartFile getMultipartFile(File file) {
        FileItem item = new DiskFileItemFactory().createItem("file"
                , MediaType.MULTIPART_FORM_DATA_VALUE
                , true
                , file.getName());
        try (InputStream input = new FileInputStream(file);
             OutputStream os = item.getOutputStream()) {
            // 流转移
            IOUtils.copy(input, os);
        } catch (Exception e) {
            throw new IllegalArgumentException("Invalid file: " + e, e);
        }
 
        return new CommonsMultipartFile(item);
    }
 
    /**
     * 将MultipartFile转换为File
     * @param multiFile
     * @return
     */
    public static File MultipartFileToFile(MultipartFile multiFile) {
        // 获取文件名
        String fileName = multiFile.getOriginalFilename();
        // 获取文件后缀
        String prefix = fileName.substring(fileName.lastIndexOf("."));
        // 若须要防止生成的临时文件重复,能够在文件名后添加随机码
 
        try {
            File file = File.createTempFile(fileName, prefix);
            multiFile.transferTo(file);
            return file;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
 
    /**
     * File进行Base64编码
     * @param file
     * @return
     * @throws Exception
     */
    public static String encodeBase64File(File file) throws Exception {
        //File file = new File(path);
        FileInputStream inputFile = new FileInputStream(file);
        byte[] buffer = new byte[(int)file.length()];
        inputFile.read(buffer);
        inputFile.close();
        return new BASE64Encoder().encode(buffer);
    }
}