java - 如何读取每行都有一个数字的文件java

Question

我有一个 spring Controller ，它使用 multipart/form-data 类型的请求。用户将上传一个文件，每行包含一个数字。每行将用新行分隔。例如:

12314
3434234
324545

我目前有以下但不确定它是否有效:

void readFile(@RequestBody MultipartFile file) throws IOException {

    List<String> listOfClientId = new ArrayList<>();
    String currentNumber = "";

    if(!file.isEmpty()){

        InputStream stream = file.getInputStream();

        int i = 0;
        while( (i=stream.read()) != -1 ) {

            if( (char) i != '\n'){
                currentNumber = currentNumber + (char) i;
            } else {
                listOfClientId.add(currentNumber);
                currentNumber = "";
            }
        }

    } else {
        System.out.println("Malformed filed.");
    }
    for(String s : listOfClientId){
        System.out.println(s);
    }
}

Answer 1

您可以像这样使用 BufferedReader :

List<String> collect;
try (BufferedReader buffer = new BufferedReader(new InputStreamReader(stream))) {
    collect = buffer.lines()
                 .collect(Collectors.toList());
}

---

如果你想获取数字列表而不是字符串，那么你可以使用:

List<Double> collect;
try (BufferedReader buffer = new BufferedReader(new InputStreamReader(stream))) {
    collect = buffer.lines()
            .map(Double::valueOf) // convert each line(String) to a Double or Integer, it depends on the size of your Numbers
            .collect(Collectors.toList());
}