java读写文件，根据指定文件名后缀读写文件夹内文件，删除文件，下载文件

男娘i 2023-06-07 10:38 19阅读 0赞

除下载文件外都已测试通过

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";
                //读写目录下匹配指定格式的文件
                getfile(filepath);
    
                String pathname = "C:\\Users\\jian.li\\Desktop\\input - 副本.log";
                //删除文件
                delFile(pathname);
            }
    
            //读取文件
            public static void readFile(String pathname) {
                String text = "";
                //防止文件建立或读取失败，用catch捕捉错误并打印，也可以throw;
                //不关闭文件会导致资源的泄露，读写文件都同理
                //Java7的try-with-resources可以优雅关闭文件，异常时自动关闭文件；详细解读https://stackoverflow.com/a/12665271
                try (FileReader reader = new FileReader(pathname);
                     // 建立一个对象，它把文件内容转成计算机能读懂的语言
                     BufferedReader br = new BufferedReader(reader)
                ) {
                    String line;
                    // 一次读入一行数据
                    while ((line = br.readLine()) != null) {
                        text = text + line + "\r\n";
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
                System.out.println(text);
                //组装每次读取的每一行，写入操作
                writeFile(text);
            }
    
            //写入文件
            public static void writeFile(String line) {
                try {
                    // 相对路径，如果没有则会建立一个新的output.log文件
                    File writeName = new File("C:\\Users\\jian.li\\Desktop\\output.log");
                    writeName.createNewFile(); // 创建新文件,有同名的文件的话直接覆盖
                    try (FileWriter writer = new FileWriter(writeName);
                         BufferedWriter out = new BufferedWriter(writer)
                    ) {
                        out.write(line);
                        // 把缓存区内容压入文件
                        out.flush();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
    
            //读取文件路径（匹配指定文件夹内以.log结尾的文件路径，自己可扩展）
             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]);
                        //只输出文件以.log结尾的路径
                        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());
                            //调用写入方法
                            readFile(readfile.getPath());
                        } else if (readfile.isDirectory()) {
                            getfile(filepath + "\\" + filelist[i]);
                        }
                    }
    
                }
    
            } catch (FileNotFoundException e) {
                System.out.println("readfile()   Exception:" + e.getMessage());
            }
        }
    
         //删除文件
         public static boolean delFile(String path) {
            System.out.println("进入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;
        }
    
    
        //下载文件 advertis为文件名 file为文件所在路径
        public static void downFile( String advertis,HttpServletResponse response) throws IOException{
                String file = "" + "/"+advertis;
            FileInputStream fileInputStream = new FileInputStream(file);
            //设置Http响应头告诉浏览器下载这个附件,下载的文件名也是在这里设置的
            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();
        }
    }