问题

Sure, here's the translated code snippet:

我有一个在Spring Boot应用程序中进行用户认证时返回的权限列表。

例如，我获取到的授权列表如下：

user_1_authority,
user_2_authority,
group_1_authority,
group_2_authority,
test_1_authority,
test_2_authority,
driver_x_authority,
...

我想要筛选这些权限，以便只返回以"user_"或"group_"开头的权限。

我想知道如何使用Java流来返回一个新的筛选后的权限列表，使其类似于：

```java
List<String> authoritiesStartingWithList = Arrays.asList("user_", "group_");

public Collection<GrantedAuthorities> filterAuthorities(Authentication authentication, List<String> authoritiesStartingWithList) {
    return authentication.getAuthorities().stream().filter(authority -> authoritiesStartingWithList.stream().anyMatch(authority::startsWith)).collect(Collectors.toList());
}

这将返回一个只包含以下内容的列表：

user_1_authority, 
user_2_authority,  
group_1_authority,  
group_2_authority,  

<details>
<summary>英文:</summary>

I have a list of authorities returned when user authenticates in Spring Boot app.

For example, I get list of granted authorities like: 

user_1_authority,
user_2_authority,
group_1_authority,
group_2_authority,
test_1_authority,
test_2_authority,
driver_x_authority,
...

I would like to filter these authorities so that I get back only authorities starting with "user_" OR "group_".

I wonder how can I use Java streams to return a new list of filtered authorities to have something like:

```java
  List<String> authoritiesStartingWithList = Arrays.asList("user_", "group_");

  public Collection<GrantedAuthorities> filterAuthorities(Authentication authentication, List<String> authoritiesStartingWithList) {
    return authentication.getAuthorities().stream().contains(authoritiesStartingWithList);
  }

this would return a list containing only:

user_1_authority, 
user_2_authority,  
group_1_authority,  
group_2_authority,  

答案1

得分: 1

尝试以下解决方案：

List<String> authoritiesStartingWithList = Arrays.asList("user_", "group_");

public Collection<GrantedAuthority> filterAuthorities(Authentication authentication, List<String> authoritiesStartingWithList) {
  return authentication.getAuthorities().stream().filter(this::startsWithOneOfPredefinedValues).collect(Collectors.toList());
}

private boolean startsWithOneOfPredefinedValues(GrantedAuthority grantedAuthority) {
  return authoritiesStartingWithList.stream().anyMatch(i->grantedAuthority.getAuthority().startsWith(i));
}

筛选方法用于迭代前缀列表，以检查是否有匹配项，如果没有找到匹配项，则将权限从流中筛选出。

List<String> authoritiesStartingWithList = Arrays.asList("user_", "group_");

public Collection<GrantedAuthority> filterAuthorities(Authentication authentication, List<String> authoritiesStartingWithList) {
  return authentication.getAuthorities().stream().filter(this::startsWithOneOfPredefinedValues).collect(Collectors.toList());
}

private boolean startsWithOneOfPredefinedValues(GrantedAuthority grantedAuthority) {
  return authoritiesStartingWithList.stream().anyMatch(i->grantedAuthority.getAuthority().startsWith(i));
}