Java IO

File.separator　　（windows 表示 \     mac 表示 / ）

@Value("${file.url}")
private String fileUrl;

//file.url=/Users/dongzejun/Desktop/ (application.properties的配置文件)
 //创建文件 exists()：判断是否存在，可能不存在
 /*File file = new File(fileUrl + "aa.txt");
 if (file != null && !file.exists()) {
     try {
         file.createNewFile();
     } catch (IOException e) {
         e.printStackTrace();
     }
 } else {
     System.out.println(File.separator);
     System.out.println(File.pathSeparator);
     System.out.println("文件已存在！");
 }*/
 //删除文件
 /*String fileName = "/Users/dongzejun/Desktop"+File.separator+"aa.txt";
 File file =new File(fileName);
 if(file.exists()){
     file.delete();
 }else {
     System.out.println("文件不存在！");
 }*/

 /*创建文件夹 mkdirs在创建时创建全路径的文件夹  mkdir只创建最后一层的文件夹
isFile()：判断是否文件，也许可能是文件或者目录*/
/* String fileName = "/Users/dongzejun/Desktop" + File.separator + "aa";
 File f = new File(fileName);
 if (!f.isFile()) {
     f.mkdirs();
 }*/

 //列出某文件夹下面的所有文件
 /*String filenName = "/Users/dongzejun/Desktop/aa" + File.separator;
 File f = new File(filenName);
 String[] str = f.list();
 for (int i = 0, j = str.length; i < j; i++) {
     System.out.println(str[i]);
 }*/

 //isDirectory判断某路径是否是目录
/* File f = new File(fileUrl);
 if (!StringUtils.isEmpty(f) && f.isDirectory()) {
     System.out.println("是文件目录");
 } else {
     System.out.println("不是文件目录！");
 }*/

 //创建新文件并用FileOutputStream字节流写入文字 (new FileOutputStream(f,true)设置true可追加文字！)
 /*File f = new File(fileUrl + "test.txt");
 OutputStream outputStream = null;
 if (f != null) {
     try {
         if (!f.exists()) {
             f.createNewFile();
         }
         outputStream = new FileOutputStream(f,true);
         String str = "just say say!!!";
         byte[] bytes = str.getBytes();
         //outputStream.write(bytes);
         for (int i = 0, j = bytes.length(); i < j; i++) {
             outputStream.write(bytes[i]);
         }
     } catch (IOException e) {
         e.printStackTrace();
     } finally {
         if (outputStream != null) {
             try {
                 outputStream.close();
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
     }
 }*/

 //利用FileInputStream字节流读取文件 当读到文件末尾的时候会返回-1
/* File f = new File(fileUrl + "test.txt");
 InputStream inputStream = null;
 try {
     if (f != null) {
         inputStream = new FileInputStream(f);
         byte[] bytes = new byte[(int) f.length()];
         //inputStream.read(bytes);
         int i = 0;
         int j = 0;
         while ((j = inputStream.read()) != (-1)) {
             bytes[i++] = (byte) j;
         }
         //console输出读取的文件内容
         System.out.println(new String(bytes).trim());
     }
 } catch (FileNotFoundException e) {
     e.printStackTrace();
 } catch (IOException e) {
     e.printStackTrace();
 } finally {
     try {
         if (inputStream != null) {
             inputStream.close();
         }
     } catch (IOException e) {
         e.printStackTrace();
     }
 }*/