1
public static String searchFile(File dir, String targetFileName) {
2
    File[] files = dir.listFiles();
3
    if (files != null) {
4
        for (File file : files) {
5
            if (file.isDirectory()) {
6
                String result = searchFile(file, targetFileName);
7
                if (result != null) {
8
                    return result;
9
                }
10
            } else {
11
                if (file.getName().equals(targetFileName)) {
12
                    return file.getAbsolutePath();
13
                }
14
            }
15
        }
16
    }
17
    return null;
18
}

1
// 缓冲字节流实现文件复制，用try-with-resource
2
try (
3
        InputStream in = new FileInputStream("D:\\test.txt");
4
        BufferedInputStream bis = new BufferedInputStream(in);
5
        OutputStream out = new FileOutputStream("D:\\test2.txt");
6
        BufferedOutputStream bos = new BufferedOutputStream(out);
7
) {
8
    byte[] buffer = new byte[1024];
9
    int len;
10
    while ((len = bis.read(buffer)) != -1) {
11
        bos.write(buffer, 0, len);
12
    }
13
} catch (IOException e) {
14
    e.printStackTrace();
15
}

1
// 缓冲字符输入流
2
try (BufferedReader br = new BufferedReader(new FileReader("test.txt"))) {
3
    String line;
4
    while ((line = br.readLine()) != null) {
5
        System.out.println(line);
6
    }
7
} catch (IOException e) {
8
    e.printStackTrace();
9
}
10
// 缓冲字符输出流
11
try (BufferedWriter bw = new BufferedWriter(new FileWriter("test.txt"))) {
12
    bw.write("hello world");
13
    bw.newLine();
14
} catch (IOException e) {
15
    e.printStackTrace();
16
}

1
// 写出
2
try (
3
        DataOutputStream dataOutputStream = new DataOutputStream(new FileOutputStream("data.txt"))
4
){
5
    dataOutputStream.writeInt(100);
6
    dataOutputStream.writeUTF("hello world");
7
} catch (IOException e) {
8
    e.printStackTrace();
9
}
10
// 读入
11
try (
12
        DataInputStream dataInputStream = new DataInputStream(new FileInputStream("data.txt"))
13
){
14
    System.out.println(dataInputStream.readInt());
15
    System.out.println(dataInputStream.readUTF());
16
} catch (IOException e) {
17
    e.printStackTrace();
18
}