Java中的IO处理
Java中的IO处理
创建文件夹:file.mkdir()
CreatDirectoryDemo.java
- package com.tianjf;
- import java.io.File;
- public class CreatDirectoryDemo {
- public static void main(String[] args) {
- String directoryName = "D:" + File.separator + "hello";
- File file = new File(directoryName);
- file.mkdir();
- }
- }
创建文件:file.createNewFile()
CreatFileDemo.java- package com.tianjf;
- import java.io.File;
- import java.io.IOException;
- public class CreatFileDemo {
- public static void main(String[] args) {
- String fileName = "D:" + File.separator + "hello.txt";
- File file = new File(fileName);
- try {
- file.createNewFile();
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- }
判断指定路径是文件夹还是文件:file.isDirectory() / file.isFile()
IsDirectoryOrFileDemo.java
- package com.tianjf;
- import java.io.File;
- public class IsDirectoryOrFileDemo {
- public static void main(String[] args) {
- String directoryName = "D:" + File.separator + "hello";
- File file = new File(directoryName);
- if (file.isDirectory()) {
- System.out.println("是一个文件夹!");
- } else {
- System.out.println("不是一个文件夹!");
- }
- String fileName = "D:" + File.separator + "hello.txt";
- file = new File(fileName);
- if (file.isFile()) {
- System.out.println("是一个文件!");
- } else {
- System.out.println("不是一个文件!");
- }
- }
- }
删除文件:file.delete()
DeleteFileDemo.java
- package com.tianjf;
- import java.io.File;
- public class DeleteFileDemo {
- public static void main(String[] args) {
- String fileName = "D:" + File.separator + "hello.txt";
- File file = new File(fileName);
- if (file.exists()) {
- file.delete();
- } else {
- System.out.println("文件不存在");
- }
- }
- }
列出所有文件夹名和所有文件名:file.list() / 列出所有文件夹路径和所有文件路径:file.listFiles()
ListFilesDemo.java
- package com.tianjf;
- import java.io.File;
- public class ListFilesDemo {
- public static void main(String[] args) {
- String directoryName = "D:" + File.separator;
- File file = new File(directoryName);
- // 列出所有文件夹名和所有文件名
- String[] arrStr = file.list();
- for (int i = 0; i < arrStr.length; i++) {
- System.out.println(arrStr[i]);
- }
- // 列出所有文件夹路径和所有文件路径
- System.out.println("---------------------------------------");
- File[] arrFile = file.listFiles();
- for (int i = 0; i < arrFile.length; i++) {
- System.out.println(arrFile[i]);
- }
- // 列出所有文件夹路径和所有文件路径
- System.out.println("---------------------------------------");
- File[] arrFileWithFilter = file.listFiles(new FilenameFilter() {// 内部类
- @Override
- public boolean accept(File f1, String name) {
- return name.endsWith(".txt");
- }
- });
- for (int i = 0; i < arrFileWithFilter.length; i++) {
- System.out.println(arrFileWithFilter[i]);
- }
- }
- }
写入字节流:FileOutputStream
FileOutputStreamDemo.java
- package com.tianjf;
- import java.io.File;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import java.io.OutputStream;
- public class FileOutputStreamDemo {
- public static void main(String[] args) throws IOException {
- /* 将一个字符串作为一个整体写入文件 */
- String fileName01 = "D:" + File.separator + "hello01.txt";
- File file01 = new File(fileName01);
- String str01 = "你好";
- byte[] bytes01 = str01.getBytes();
- OutputStream out01 = new FileOutputStream(file01);
- out01.write(bytes01);
- // 刷新缓存,写文件,最好加上这样的一句话
- out01.flush();
- out01.close();
- /* 将一个字符串一个字节一个字节的写入文件 */
- String fileName02 = "D:" + File.separator + "hello02.txt";
- File file02 = new File(fileName02);
- String str02 = "你好";
- byte[] bytes02 = str02.getBytes();
- OutputStream out02 = new FileOutputStream(file02);
- for (int i = 0; i < bytes02.length; i++) {
- out02.write(bytes02[i]);
- }
- out02.flush();
- out02.close();
- /* 追加新内容到文件中 */
- String str03 = "追加的内容";
- byte[] bytes03 = str03.getBytes();
- OutputStream out03 = new FileOutputStream(file02, true);
- for (int i = 0; i < bytes03.length; i++) {
- out03.write(bytes03[i]);
- }
- out03.flush();
- out03.close();
- }
- }
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