java讀寫文件，根據指定文件名後綴讀寫文件夾內文件，刪除文件，下載文件

除下載文件外都已測試通過

package com.goldpac.ocs.common.gatewaymanagerservice.service.impl;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;

public class test {

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

            String filepath = "C:\\Users\\jian.li\\Desktop";
            //讀寫目錄下匹配指定格式的文件
            getfile(filepath);

            String pathname = "C:\\Users\\jian.li\\Desktop\\input - 副本.log";
            //刪除文件
            delFile(pathname);
        }

        //讀取文件
        public static void readFile(String pathname) {
            String text = "";
            //防止文件建立或讀取失敗，用catch捕捉錯誤並打印，也可以throw;
            //不關閉文件會導致資源的泄露，讀寫文件都同理
            //Java7的try-with-resources可以優雅關閉文件，異常時自動關閉文件；詳細解讀https://stackoverflow.com/a/12665271
            try (FileReader reader = new FileReader(pathname);
                 // 建立一個對象，它把文件內容轉成計算機能讀懂的語言
                 BufferedReader br = new BufferedReader(reader)
            ) {
                String line;
                // 一次讀入一行數據
                while ((line = br.readLine()) != null) {
                    text = text + line + "\r\n";
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            System.out.println(text);
            //組裝每次讀取的每一行，寫入操作
            writeFile(text);
        }

        //寫入文件
        public static void writeFile(String line) {
            try {
                // 相對路徑，如果沒有則會建立一個新的output.log文件
                File writeName = new File("C:\\Users\\jian.li\\Desktop\\output.log");
                writeName.createNewFile(); // 創建新文件,有同名的文件的話直接覆蓋
                try (FileWriter writer = new FileWriter(writeName);
                     BufferedWriter out = new BufferedWriter(writer)
                ) {
                    out.write(line);
                    // 把緩存區內容壓入文件
                    out.flush();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        //讀取文件路徑（匹配指定文件夾內以.log結尾的文件路徑，自己可擴展）
         public static void getfile(String filepath) throws FileNotFoundException, IOException {
        try {

            File file = new File(filepath);
            if (!file.isDirectory()) {
                System.out.println("文件");
                System.out.println("path=" + file.getPath());
                System.out.println("absolutepath=" + file.getAbsolutePath());
                System.out.println("name=" + file.getName());

            } else if (file.isDirectory()) {
                String[] filelist = file.list();
                for (int i = 0; i < filelist.length; i++) {
                    File readfile = new File(filepath + "\\" + filelist[i]);
                    //只輸出文件以.log結尾的路徑
                    if (!readfile.isDirectory() && "log".equals(readfile.getName().substring(readfile.getName().lastIndexOf(".")+1,readfile.getName().length()))) {
                        System.out.println("path=" + readfile.getPath());
                        System.out.println("absolutepath="
                                + readfile.getAbsolutePath());
                        System.out.println("name=" + readfile.getName());
                        //調用寫入方法
                        readFile(readfile.getPath());
                    } else if (readfile.isDirectory()) {
                        getfile(filepath + "\\" + filelist[i]);
                    }
                }

            }

        } catch (FileNotFoundException e) {
            System.out.println("readfile()   Exception:" + e.getMessage());
        }
    }

     //刪除文件
     public static boolean delFile(String path) {
        System.out.println("進入deFile方法 psth =: "+path);
        boolean flag = false;
        File file = new File(path);
        System.out.println("操作文件文件，文件列表如下~~__--~~~~~~~~~~~~~~~~~~~：：:"+file);
        if (!file.exists()) {
            return flag;
        }
        try{
            flag = file.delete();
        }catch (Exception e){
            e.printStackTrace();
        }
        return flag;
    }


    //下載文件 advertis爲文件名 file爲文件所在路徑
    public static void downFile( String advertis,HttpServletResponse response) throws IOException{
            String file = "" + "/"+advertis;
        FileInputStream fileInputStream = new FileInputStream(file);
        //設置Http響應頭告訴瀏覽器下載這個附件,下載的文件名也是在這裏設置的
        response.setHeader("Content-Disposition", "attachment;Filename=" + URLEncoder.encode(advertis, "UTF-8"));
        OutputStream outputStream = response.getOutputStream();
        byte[] bytes = new byte[2048];
        int len = 0;
        while ((len = fileInputStream.read(bytes))>0){
            outputStream.write(bytes,0,len);
        }
        fileInputStream.close();
        outputStream.close();
    }
}