Java文件基本操作总结

public static void main(String[] args) {
    // 创建目录
    File directory = new File("D:/temp");
    boolean directoryDoesNotExists = ! directory.exists();
    if (directoryDoesNotExists) {
        // mkdir是创建单级目录
        // mkdirs是连续创建多级目录
        directory.mkdirs();

    }
    // 创建文件
    File file = new File("D:/temp/test.txt");
    boolean fileDoesNotExsits = ! file.exists();
    if (fileDoesNotExsits) {
        try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 遍历directory下的所有文件消息
    File[] files = directory.listFiles();
    for (File file1 : files) {
        System.out.println(file1.getPath());
    }

}

public static void main(String[] args) {
    // Path和java.io.File基本类似
    Path path = FileSystems.getDefault().getPath("D:/temp", "abc.txt");
    // D:/ 返回1 D:/temp 返回2
    System.out.println(path.getNameCount());

    // 用File的toPath()方法获取Path对象
    File file = new File("D:/temp/abc.txt");
    Path path1 = file.toPath();
    System.out.println(path.compareTo(path1)); // 结果为0 说明两个path相等
    // 获取Path方法三
    Path path3 = Paths.get("D:/temp", "abc.txt");
    // 判断文件是否可读
    System.out.println("文件是否可以读取: " + Files.isReadable(path));
}

public static void main(String[] args) {
    // 移动文件
    moveFile();
    // 访问文件属性
    fileAttributes();
    // 创建目录
    createDirectory();
}

private static void createDirectory() {
    Path path = Paths.get("D:/temp/test");
    try {
        // 创建文件夹
        if (Files.notExists(path)) {
            Files.createDirectory(path);
        } else {
            System.out.println("文件夹创建失败");
        }
        Path path2 = path.resolve("a.java");
        Path path3 = path.resolve("b.java");
        Path path4 = path.resolve("c.txt");
        Path path5 = path.resolve("d.jpg");
        Files.createFile(path2);
        Files.createFile(path3);
        Files.createFile(path4);
        Files.createFile(path5);

        // 不带条件的遍历输出
        DirectoryStream<Path> listDirectory = Files.newDirectoryStream(path);
        for (Path path1 : listDirectory) {
            System.out.println(path1.getFileName());
        }
        // 创建一个带有过滤器，过滤文件名以java txt结尾的文件
        DirectoryStream<Path> pathsFilter = Files.newDirectoryStream(path, "*.{java,txt}");
        for (Path item : pathsFilter) {
            System.out.println(item.getFileName());
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

@SuppressWarnings("all")
private static void fileAttributes() {
    Path path = Paths.get("D:/temp");
    // 判断是否是目录
    System.out.println(Files.isDirectory(path, LinkOption.NOFOLLOW_LINKS));
    try {
        // 获取文件的基础属性
        BasicFileAttributes attributes = Files.readAttributes(path, BasicFileAttributes.class);
        // 判断是否是目录
        System.out.println(attributes.isDirectory());
        // 获取文件最后修改时间
        System.out.println(new Date(attributes.lastModifiedTime().toMillis()).toLocaleString());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

private static void moveFile() {
    Path from = Paths.get("D:/temp", "text.txt");
    // 将文件移动到D:/temp/test/text.txt, 如果目标文件以存在则替换
    Path to = from.getParent().resolve("test/text.txt");
    try {
        // 文件大小bytes
        System.out.println(Files.size(from));
        // 调用文件移动方法，如果目标文件已存在则替换
        Files.move(from, to, StandardCopyOption.REPLACE_EXISTING);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public class Demo2 {
    public static void main(String[] args) {
        // 查找以.jpg结尾的
        String ext = "*.jpg";
        Path fileTree = Paths.get("D:/temp/");
        Search search = new Search(ext);
        EnumSet<FileVisitOption> options = EnumSet.of(FileVisitOption.FOLLOW_LINKS);
        try {
            Files.walkFileTree(fileTree, options, Integer.MAX_VALUE, search);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
class Search implements FileVisitor {
    private PathMatcher matcher;
    public Search(String ext) {
        this.matcher = FileSystems.getDefault().getPathMatcher("glob:" + ext);
    }

    public void judgeFile(Path file) throws IOException {
        Path name = file.getFileName();
        if (name != null && matcher.matches(name)) {
            // 文件名匹配
            System.out.println("匹配的文件名: " + name);
        }
    }
    // 访问目录前调用
    @Override
    public FileVisitResult preVisitDirectory(Object dir, BasicFileAttributes attrs) throws IOException {
        return FileVisitResult.CONTINUE;
    }
    // 访问文件时调用
    @Override
    public FileVisitResult visitFile(Object file, BasicFileAttributes attrs) throws IOException {
        judgeFile((Path) file);
        return FileVisitResult.CONTINUE;
    }
    // 访问文件失败后调用
    @Override
    public FileVisitResult visitFileFailed(Object file, IOException exc) throws IOException {
        return FileVisitResult.CONTINUE;
    }
    // 访问一个目录后调用
    @Override
    public FileVisitResult postVisitDirectory(Object dir, IOException exc) throws IOException {
        System.out.println("postVisit: " + (Path) dir);
        return FileVisitResult.CONTINUE;
    }
}

public static void main(String[] args) {
    writeFile();
}

public static void writeFile(){
    try (BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("D:/temp/demo3.txt")))) {
        bw.write("hello world");
        bw.newLine();
        bw.write("Java Home");
        bw.newLine();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {
    readerFile();
}

private static void readerFile() {
    String line = "";
    try (BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("D:/temp/demo3.txt")))) {
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {
    writeFile();
}

private static void writeFile() {
    try (DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("D:/temp/test.dat")))) {
        dos.writeUTF("hello");
        dos.writeUTF("hello world is test bytes");
        dos.writeInt(20);
        dos.writeUTF("world");
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {
   readFile();
}

private static void readFile() {
    try (DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream("D:/temp/test.dat")))) {
        System.out.println(in.readUTF() + in.readUTF() + in.readInt() + in.readUTF());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

// 多个文件压缩
public static void main(String[] args) {
    zipFile();
}
public static void zipFile() {
    File file = new File("D:/temp");
    File zipFile = new File("D:/temp.zip");
    FileInputStream input = null;
    try (ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(zipFile))) {
        // 添加注释
        zos.setComment(new String("多个个文件压缩".getBytes(),"UTF-8"));

        // 压缩过程
        int temp = 0;
        // 判断是否为文件夹
        if (file.isDirectory()) {
            File[] listFile = file.listFiles();
            for (int i = 0; i < listFile.length; i++) {
                    // 定义文件的输出流
                    input = new FileInputStream(listFile[i]);
                    // 设置Entry对象
                    zos.putNextEntry(new ZipEntry(file.getName() +
                            File.separator + listFile[i].getName() ));
                    System.out.println("正在压缩: " + listFile[i].getName());
                    // 读取内容
                    while ((temp = input.read()) != -1) {
                        // 压缩输出
                        zos.write(temp);
                    }
                    // 关闭输入流
                    input.close();
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

// 多个文件解压缩
public static void main(String[] args) throws Exception{
    // 待解压的zip文件，需要在zip文件上构建输入流，读取数据到Java中
    File file = new File("C:\\Users\\Wong\\Desktop\\test.zip");

    // 输出文件的时候要有文件夹的操作
    File outFile = null;
    // 实例化ZipEntry对象
    ZipFile zipFile = new ZipFile(file);

    // 定义解压的文件名
    OutputStream out = null;
    // 定义输入流，读取每个Entry
    InputStream input = null;
    // 每一个压缩Entry
    ZipEntry entry = null;
    
    // 定义压缩输入流,实例化ZipInputStream
    try (ZipInputStream zipInput = new ZipInputStream(new FileInputStream(file))) {
        // 遍历压缩包中的文件
        while ((entry = zipInput.getNextEntry()) != null) {
            System.out.println("解压缩 " + entry.getName().replaceAll("/", "") + " 文件");
            // 定义输出的文件路径
            outFile = new File("D:/" + entry.getName());
            
            boolean outputDirectoryNotExsits = !outFile.getParentFile().exists();
            // 当输出文件夹不存在时
            if (outputDirectoryNotExsits) {
                // 创建输出文件夹
                outFile.getParentFile().mkdirs();
            }
            
            boolean outFileNotExists = !outFile.exists();
            // 当输出文件不存在时
            if (outFileNotExists) {
                if (entry.isDirectory()) {
                    outFile.mkdirs();
                } else {
                    outFile.createNewFile();
                }
            }

            boolean entryNotDirctory = !entry.isDirectory();
            if (entryNotDirctory) {
                input = zipFile.getInputStream(entry);
                out = new FileOutputStream(outFile);
                int temp = 0;
                while ((temp = input.read()) != -1) {
                    out.write(temp);
                }
                input.close();
                out.close();
                System.out.println("解压缩成功");
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}