Java操作文件

import lombok.extern.log4j.Log4j2;
import org.springframework.web.multipart.MultipartFile;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;



@Log4j2
public class FileUtils {

    
    public static String upload(MultipartFile file, String path) {
        //获取文件名后缀
        String fileLastType = file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."));
        //使用原文件名
        String realPath = path + "/" + file.getOriginalFilename();
        File dest = new File(realPath);
        //判断文件父目录是否存在
        if (!dest.getParentFile().exists()) {
            dest.getParentFile().mkdir();
        }
        try {
            //保存文件
            file.transferTo(dest);
            return newFileName + fileLastType;
        } catch (IllegalStateException e) {
            log.error(e);
            return "error";
        } catch (IOException e) {
            log.error(e);
            return "error";
        }

    }

    
    public static void fromUrlDownloadFile(String fileUrl, String fileLocal) throws Exception {
        URL url = new URL(fileUrl);
        HttpURLConnection urlCon = (HttpURLConnection) url.openConnection();
        urlCon.setConnectTimeout(6000);
        urlCon.setReadTimeout(6000);
        int code = urlCon.getResponseCode();
        if (code != HttpURLConnection.HTTP_OK) {
            throw new Exception("文件读取失败");
        }
        //读文件流
        DataInputStream in = new DataInputStream(urlCon.getInputStream());
        DataOutputStream out = new DataOutputStream(new FileOutputStream(fileLocal));
        byte[] buffer = new byte[2048];
        int count = 0;
        while ((count = in.read(buffer)) > 0) {
            out.write(buffer, 0, count);
        }
        out.close();
        in.close();
    }

    
    public static void saveJsonFile(String s, String name) {
        File file = new File(name);
        try {
            //检查文件的目录是否存在，不存在创建
            if (!file.getParentFile().exists()) {
                file.getParentFile().mkdirs();
            }
            //验证文件是否存在，存在即删除
            if (file.exists()) {
                file.delete();
            }
            //创建文件
            file.createNewFile();
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(new File(name)), "utf-8"));
            bw.write(s);
            bw.flush();
            bw.close();
            // fw.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        log.info("文件生成完毕：" + name);
    }


    
    public static String readFile(String filename) {
        StringBuffer sbf = new StringBuffer();
        try {
            BufferedReader in = new BufferedReader(new FileReader(filename));
            String str;
            while ((str = in.readLine()) != null) {
                sbf.append(str);
            }
        } catch (IOException e) {
            log.error("读取文件异常：" + e.getMessage());
        }
        return sbf.toString();
    }


    
    public static void addContent(String message, String filename) {
        File file = new File(filename);
        try {
            //检查文件的目录是否存在，不存在创建
            if (!file.getParentFile().exists()) {
                file.getParentFile().mkdirs();
            }
            //验证文件是否存在，不存在创建新的文件
            if (!file.exists()) {
                //创建文件
                file.createNewFile();
            }
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file, true), "utf-8"));
            bw.write(message);
            bw.flush();
            bw.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}