Java 逐行读取文件

 BufferedReader br = new BufferedReader(
     new InputStreamReader(new FileInputStream(new File("C:/Users/LetGo/Desktop/messages")
     ),StandardCharsets.UTF_8));
String s=br.readLine() != null);

File -> FileInputStream ->InputStreamReader -> BufferedReader

InputStream stream = getClass().getClassLoader().getResourceAsStream(
    "messages");
assert stream != null;
BufferedReader br = new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8));
String s=br.readline();

只能读取当前工程下文件