java---积累---修改File文件的权限

谁践踏了优雅 2023-03-02 13:16 5阅读 0赞

使用上传文件的代码如下:

private static final int ALLOW_DOWNLOAD_COUNT = 2;
    
    	private static Map<String, Integer> downloadRecordMap = new HashMap<String, Integer>();
    
    	private String barcodeFilePathPrefix="/data/result";
    
    	/**
    	 * 
    	 * 判断文件是否存在
    	 *
    	 */
    	@RequestMapping("/sampleFile/exists")
    	@ResponseBody
    	public Object existsFile(String fileName) {
    		File file = new File(barcodeFilePathPrefix, fileName);
    		if (file.exists()) {
    			return AjaxResult.RESULT_SUCCESS;
    		} else {
    			return AjaxResult.RESULT_ERROR;
    		}
    	}
    
    	/**
    	 * 
    	 * 样本文件上传
    	 * 
    	 */
    	@RequestMapping("/sampleFile/upload")
    	@ResponseBody
    	public Object fileupload(HttpServletRequest request, @RequestParam("sampleFile") CommonsMultipartFile sampleFile) {
    		AdminUser adminUser = (AdminUser) request.getSession().getAttribute("nowManager");
    		String name = (adminUser != null ? adminUser.getUsername().toString() : "未登录");
    		try {
    			String fileName = sampleFile.getOriginalFilename();
    			File destfile = new File(barcodeFilePathPrefix, fileName);
    			SampleFileLog sampleFileLog=new SampleFileLog();
    			sampleFileLog.setAction("上传文件"+fileName);
    			sampleFileLog.setOperator(name);
    			sampleFileLog.setTime(new Date());
    			logMongoTemplate.save(sampleFileLog);
    			if (!destfile.exists()) { // 文件不存在
    				destfile.createNewFile();
    				copyFile(sampleFile.getInputStream(), destfile);
    			} else { // 文件存在
    				copyFile(sampleFile.getInputStream(), destfile);
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    			return AjaxResult.resultError(e.getMessage());
    		}
    		return AjaxResult.RESULT_SUCCESS;
    	}
    
    	@RequestMapping("/sampleFile/download")
    	public void fileDownload(HttpServletRequest request, @RequestParam("fileName") String fileName,
    			HttpServletResponse response) throws IOException {
    
    		AdminUser adminUser = (AdminUser) request.getSession().getAttribute("nowManager");
    		String name = (adminUser != null ? adminUser.getUsername().toString() : "未登录");
    		SampleFileLog sampleFileLog=new SampleFileLog();
    		sampleFileLog.setAction("下载文件"+fileName);
    		sampleFileLog.setOperator(name);
    		sampleFileLog.setTime(new Date());
    		logMongoTemplate.save(sampleFileLog);
    		int i = downloadRecordMap.get(name)==null?0:downloadRecordMap.get(name);
    		if (i > ALLOW_DOWNLOAD_COUNT) {
    			response.getWriter()
    					.println("<!DOCTYPE HTML>\r\n" + "<html>\r\n" + "<head><meta charset=\"utf-8\"> \r\n" + "<title>超过下载次数,请联系管理员</title>\r\n"
    							+ "</head>\r\n" + "<body>\r\n" + "  <h1>超过下载次数,请联系管理员</h1>\r\n" + "</body>\r\n"
    							+ "</html>\r\n" + "");
    			return;
    		}
    		i = i+1;
    		downloadRecordMap.put(name, i);
    		try {
    			File file = new File(barcodeFilePathPrefix, fileName);
    			if (file.exists()) {
    				response.setHeader("content-disposition",
    						"attachment;filename=" + URLEncoder.encode(file.getName(), "UTF-8"));
    
    				StringBuffer buffer = new StringBuffer();
    				BufferedReader fileInput = new BufferedReader(new FileReader(file));
    				String line = null;
    				while (StringUtils.isNotBlank(line = fileInput.readLine())) {
    					buffer.append(line + "\n");
    				}
    				response.getWriter().write(buffer.toString());
    				fileInput.close();
    				return;
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    
    		response.getWriter().println("<!DOCTYPE HTML>\r\n" + "<html>\r\n" + "<head><meta charset=\"utf-8\">\r\n" + "<title>没找到文件</title>\r\n"
    				+ "</head>\r\n" + "<body>\r\n" + "  <h1>没找到文件</h1>\r\n" + "</body>\r\n" + "</html>\r\n" + "");
    	}
    
    
    
    
    	/**
    	 * 文件复制
    	 * 
    	 * @param sourceInputStream
    	 * @param destFile
    	 * @throws IOException
    	 */
    	private void copyFile(InputStream sourceInputStream, File destFile) throws IOException {
    		BufferedReader sourceReader = new BufferedReader(new InputStreamReader(sourceInputStream));
    		BufferedWriter destWriter = new BufferedWriter(new FileWriter(destFile));
    		String line = null;
    		while ((line = sourceReader.readLine()) != null) {
    			destWriter.write(line);
    			destWriter.newLine();
    		}
    		sourceReader.close();
    		destWriter.close();
    	}

可能遇到的问题—上传的文件其他程序和用户无法读取—Permission denied

原因是 调用createNewFile（）方法默认的权限是644

在java中修改File权限的几种方式

方案一 使用File的方法

import java.io.File; 
    2.import java.io.IOException; 
    
    
    public class FilePermission  
    { 
        public static void main( String[] args ) 
        {    
            try { 
                File file = new File("/home/test3.txt"); 
              if (file.createNewFile()){ 
                  System.out.println("File is created!"); 
                 file.setExecutable(true);//设置可执行权限 
                 file.setReadable(true);//设置可读权限 
                 file.setWritable(true);//设置可写权限 
                 System.out.println("is execute allow : " + file.canExecute()); 
                 System.out.println("is read allow : " + file.canRead()); 
                  System.out.println("is write allow : " + file.canWrite()); 
              }else{ 
                  System.out.println("File already exists."); 
             } 
         } catch (IOException e) { 
              e.printStackTrace();<pre class="java" name="code"></pre> 
            } 
        }

方案二 调用系统层面的shell命令chmod运行

Runtime runtime = getRuntime();
    String command = "chmod 770 " + dirPath;
    try {
        Process process = runtime.exec(command);
        process.waitFor();
        int existValue = process.exitValue();
        if(existValue != 0){
            logger.log(Level.SEVERE, "Change file permission failed.");
            }
         } catch (Exception e) {
            logger.log(Level.SEVERE, "Command execute failed.", e);
         }

注意 该使用该方式时，路径值不能包含空格和分号，否则会造成安全风险。如下:  
当dirPath带有空格如下:

dirPath = /home/a    aa.txt

当我们运行

chmod 770 /home/a    aa.txt

实际运行的命令效果等同于

chmod 770 /home/a
    chmod 770 aa.txt

/home/a整个目录都会被修改成770权限，不符合预期只修改一个文件。

方案三–NIO方式

private void changeFolderPermission(File dirFile) throws IOException {
        Set<PosixFilePermission> perms = new HashSet<PosixFilePermission>();
        perms.add(PosixFilePermission.OWNER_READ);
        perms.add(PosixFilePermission.OWNER_WRITE);
        perms.add(PosixFilePermission.OWNER_EXECUTE);
        perms.add(PosixFilePermission.GROUP_READ);
        perms.add(PosixFilePermission.GROUP_WRITE);
        perms.add(PosixFilePermission.GROUP_EXECUTE);
        try {
            Path path = Paths.get(dirFile.getAbsolutePath());
            Files.setPosixFilePermissions(path, perms);
        } catch (Exception e) {
            logger.log(Level.SEVERE, "Change folder " + dirFile.getAbsolutePath() + " permission failed.", e);
            }
        }

参考链接:  
https://www.jb51.net/article/167122.htm