Java编程中最基础的文件和目录操作方法详解
文件操作 平常经常使用JAVA对文件进行读写等操作,这里汇总一下常用的文件操作。 1、创建文件 public static boolean createFile(String filePath){ boolean result = false; File file = new File(filePath); if(!file.exists()){ try { result = file.createNewFile(); } catch (IOException e) { e.printStackTrace(); } } return result; } 2、创建文件夹 public static boolean createDirectory(String directory){ boolean result = false; File file = new File(directory); if(!file.exists()){ result = file.mkdirs(); } return result; } 3、删除文件 public static boolean deleteFile(String filePath){ boolean result = false; File file = new File(filePath); if(file.exists() && file.isFile()){ result = file.delete(); } return result; } 4、删除文件夹 递归删除文件夹下面的子文件和文件夹 public static void deleteDirectory(String filePath){ File file = new File(filePath); if(!file.exists()){ return; } if(file.isFile()){ file.delete(); }else if(file.isDirectory()){ File[] files = file.listFiles(); for (File myfile : files) { deleteDirectory(filePath + "/" + myfile.getName()); } file.delete(); } } 5、读文件 (1)以字节为单位读取文件,常用于读二进制文件,如图片、声音、影像等文件 public static String readFileByBytes(String filePath){ File file = new File(filePath); if(!file.exists() || !file.isFile()){ return null; } StringBuffer content = new StringBuffer(); try { byte[] temp = new byte[1024]; FileInputStream fileInputStream = new FileInputStream(file); while(fileInputStream.read(temp) != -1){ content.append(new String(temp)); temp = new byte[1024]; } fileInputStream.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return content.toString(); } (2)以字符为单位读取文件,常用于读文本,数字等类型的文件,支持读取中文 public static String readFileByChars(String filePath){ File file = new File(filePath); if(!file.exists() || !file.isFile()){ return null; } StringBuffer content = new StringBuffer(); try { char[] temp = new char[1024]; FileInputStream fileInputStream = new FileInputStream(file); InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream,"GBK"); while(inputStreamReader.read(temp) != -1){ content.append(new String(temp)); temp = new char[1024]; } fileInputStream.close(); inputStreamReader.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return content.toString(); } (3)以行为单位读取文件,常用于读面向行的格式化文件 public static List<String> readFileByLines(String filePath){ File file = new File(filePath); if(!file.exists() || !file.isFile()){ return null; } List<String> content = new ArrayList<String>(); try { FileInputStream fileInputStream = new FileInputStream(file); InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream,"GBK"); BufferedReader reader = new BufferedReader(inputStreamReader); String lineContent = ""; while ((lineContent = reader.readLine()) != null) { content.add(lineContent); System.out.println(lineContent); } fileInputStream.close(); inputStreamReader.close(); reader.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return content; } 6、写文件 字符串写入文件的几个类中,FileWriter效率最高,BufferedOutputStream次之,FileOutputStream最差。 (1)通过FileOutputStream写入文件 public static void writeFileByFileOutputStream(String filePath,String content) throws IOException{ File file = new File(filePath); synchronized (file) { FileOutputStream fos = new FileOutputStream(filePath); fos.write(content.getBytes("GBK")); fos.close(); } } (2)通过BufferedOutputStream写入文件 public static void writeFileByBufferedOutputStream(String filePath,String content) throws IOException{ File file = new File(filePath); synchronized (file) { BufferedOutputStream fos = new BufferedOutputStream(new FileOutputStream(filePath)); fos.write(content.getBytes("GBK")); fos.flush(); fos.close(); } } (3)通过FileWriter将字符串写入文件 public static void writeFileByFileWriter(String filePath,String content) throws IOException{ File file = new File(filePath); synchronized (file) { FileWriter fw = new FileWriter(filePath); fw.write(content); fw.close(); } } 目录操作 创建目录 mkdir( ) 方法创建了一个目录,成功返回 true ,创建失败返回 false。失败情况是指文件对象的路径已经存在了,或者无法创建目录,因为整个路径不存在。 import java.io.File; public class CreateDir { public static void main(String args[]) { String dirname = "/tmp/user/java/bin"; File d = new File(dirname); // Create directory now. d.mkdirs(); } } 编译并执行以上代码创建 “/ tmp /user/ java / bin”。 提示:Java 自动按 UNIX 和 Windows 约定来处理路径分隔符。如果在 Windows 版本的 Java 中使用正斜杠(/),仍然可以得到正确的路径。 目录列表 import java.io.File; public class ReadDir { public static void main(String[] args) { File file = null; String[] paths; try{ // create new file object file = new File("/tmp"); // array of files and directory paths = file.list(); // for each name in the path array for(String path:paths) { // prints filename and directory name System.out.println(path); } }catch(Exception e){ // if any error occurs e.printStackTrace(); } } } 基于你/ tmp目录下可用的目录和文件,将产生以下结果: test1.txt test2.txt ReadDir.java ReadDir.class (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |