功能强大的Paths类和Files类

Paths

用于来表示文件路径和文件 示例：

@Test
public void testPath() throws IOException {
    //构造Path类对象
    File file = new File("E:/blog");
    System.out.println(file.toURI()); // file:/E:/blog/
    Path path = file.toPath();

    URI uri = URI.create("file:///E:/blog3");
    Path path1 = Paths.get(uri);

    Path path2 = Paths.get("E:/", "blog1");
    Path path3 = Paths.get("E:/blog2");

    Path path4 = FileSystems.getDefault().getPath("E:/", "blog4");

    //判断是否存在
    System.out.println(Files.exists(path));

    //如果文件（目录）不存在创建文件
    if (!Files.exists(path1)) {
        Files.createDirectory(path1);//创建目录
    }
    if (!Files.exists(path2)) {
        Files.createFile(path2);//创建文件
    }
}

Files

文件操作工具类。

1、文件复制

public static void main(String[] args) throws IOException { 
   Files.copy(Paths.get("E:/1234/db_wego.sql"),System.out);
   Files.copy(System.in,Paths.get("E:/aa.txt"), StandardCopyOption.REPLACE_EXISTING);
   Files.copy(Paths.get("E:/1234/db_wego.sql"),Paths.get("E:/aa.txt"),StandardCopyOption.REPLACE_EXISTING);
}

相关方法介绍：

• 从文件复制到文件：Files.copy(Path source, Path target, CopyOption options);
• 从输入流复制到文件：Files.copy(InputStream in, Path target, CopyOption options);
• 从文件复制到输出流：Files.copy(Path source, OutputStream out);

2、写文件

@Test
public void fun4() throws IOException {
    BufferedWriter bw = Files.newBufferedWriter(Paths.get("E:/1234/dd.sql"), StandardCharsets.UTF_8);
    bw.write("haha");
    bw.flush();
    bw.close();
}

3、读文件

@Test
public void fun5() throws IOException {//
    BufferedReader br = Files.newBufferedReader(Paths.get("E:/1234/db_wego.sql"), StandardCharsets.UTF_8);
    //注意：如果指定的字符编码不对，可能会抛出MalformedInputException异常
    String res = null;
    while ((res = br.readLine()) != null) {
        System.out.println(res);
    }
    br.close();
}

4、遍历文件夹

@Test
public void fun6() throws IOException {
    Path path = Paths.get("E:/1234");
    //方式一
    Files.newDirectoryStream(path)
            .forEach(item -> System.out.println(item.getFileName()));
    //方式二
    Files.list(path).forEach(item -> System.out.println(item.getFileName()));
}

5、递归遍历文件夹

@Test
public void fun7() throws IOException {
    Path root = Paths.get("E:/Workspaces/Project/Blog/src/test/java/com/hc");
    List result = new LinkedList();
    Files.walkFileTree(root, new FindJavaVisitor(result));
    result.forEach(System.out::println);
}

private   class FindJavaVisitor extends SimpleFileVisitor {
    private List res;
    public FindJavaVisitor(List result){
        this.res = result;
    }
    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs){
        if(file.toString().endsWith(".java")){
            res.add(file.getFileName());
        }
        return FileVisitResult.CONTINUE;
    }
}