math - 在Dart中使用parseInt时服务器崩溃？

Question

不知道我在做什么错。我有一个很小的程序设置来解析本地主机上的请求。我的客户有:

var local_num = null; // init to null
// my server is running on localhost at the moment
// using XMLHttpRequest I send it the value (it woud still be null)
request.open('GET', 'http://127.0.0.1:8080?player=${local_num}', false);

我的服务器代码应该能够处理此问题:

action = params['action'];
var player_num = params['player'];
print ("got player num ${player_num}");
print(player_num is num); // false in both cases (see log below)
print(player_num is int);

if (player_num == null) { // never reaches inside of this if clause
print("received num is null, skipping parsing");
} else {
  try {
    var actual_number = Math.parseInt(received_num);
    print("parsed"); // never gets here
  } catch(var e) {
print(e); // should throw...
  }
}

服务器记录以下内容:

// it gets the request, player is null...
Instance of '_HttpRequest@14117cc4'
{player: null}
got player num null
false
false

但是，BOOM! ->在dart:bootstrap_impl ...行1255附近

int pow(int exponent) {
  throw "Bigint.pow not implemented";
}

Answer 1

我目前看到的主要问题是:

if (player_num == null) {

在这种情况下，您要检查player_num是否为空值。但是，您无需检查该值是否为字符串“null”(在这种情况下看起来好像是)。

从这一点开始，当您将其传递给parseInt时，它应该引发FormatException(注意:不应使用Math。static类，因为它是dart:math中的顶级函数。静态类Math。仍来自dart:核心)。

话虽这么说，我的尝试/捕获与parseInt('null');确实确实捕获了错误。我感到困惑的是，您的错误表明正在显示的错误是针对'pow()'函数的，而与parseInt()根本无关。