URL解析query的坑-526互联

本来是想根据url解析参数成Map,结果不留神,留下了个坑.....测试的时候才发现,看来还是对api不是很熟悉,没有注意源码

//...
private static final Pattern PARAM_PATTERN = Pattern.compile("(?<key>\\w+)=(?<value>\\w+)&?");
//...
URL u = getURL(url);
Map<String, String> params = parseQuery2Param(u.getQuery());
//...

private Map<String, String> parseQuery2Param(String query) {
  Map<String, String> params = new HashMap<>();
  Matcher matcher = PARAM_PATTERN.matcher(query);
  while (matcher.find()) {
    String key = matcher.group("key");
    String value = matcher.group("value");
    params.put(key, value);
    System.out.println(key + ":" + value);
  }
  return params;
}

这个本来想着没啥问题,结果当url没有参数的时候,直接返回了null,导致正则出现了问题NPE
看api才知道

  /**
   * Gets the query part of this {@code URL}.
   *
   * @return  the query part of this {@code URL},
   * or <CODE>null</CODE> if one does not exist
   * @since 1.3
   */
  public String getQuery() {
      return query;
  }

吃一堑长一智了

solution qtree2 qtree query