如何在 JSP / Servlet 中获取用户角色

Question

有没有什么方法可以获取一个字符串[] 与用户在 JSP 或 Servlet 中的角色？

我知道 request.isUserInRole("role1") 但我也想知道用户的所有角色。

我搜索了 servlet 源，似乎这是不可能的，但这对我来说似乎很奇怪。

那么……有什么想法吗？

Answer 1

答案很混乱。

首先你需要找出你的 webapp 中 request.getUserPrincipal() 返回的类型。

    System.out.println("type = " + request.getUserPrincipal().getClass());

假设返回 org.apache.catalina.realm.GenericPrincipal。

然后将 getUserPrincipal() 的结果转换为该类型并使用它提供的方法。

    final Principal userPrincipal = request.getUserPrincipal();
    GenericPrincipal genericPrincipal = (GenericPrincipal) userPrincipal;
    final String[] roles = genericPrincipal.getRoles();

我说这会很乱。它也不是很便携。

Answer 2

阅读所有可能的角色，或硬编码一个列表。然后运行 ​​isUserInRole 对其进行迭代并构建用户所在角色的列表，然后将列表转换为数组。

String[] allRoles = {"1","2","3"};
HttpServletRequest request = ... (or from method argument)
List userRoles = new ArrayList(allRoles.length);
for(String role : allRoles) {
 if(request.isUserInRole(role)) { 
  userRoles.add(role);
 }
}

// I forgot the exact syntax for list.toArray so this is prob wrong here
return userRoles.toArray(String[].class);

Answer 3

在 WebLogic 中，您可以这样做：

import weblogic.security.Security;
import weblogic.security.SubjectUtils;
...
private List<String> getUserRoles()  {
    return Arrays.asList(SubjectUtils.getPrincipalNames(Security.getCurrentSubject()).split("/"));
}

请注意，列表中的第一个元素是用户名。

Answer 4

在符合 JACC 的应用服务器上——理论上每个完整的 Java EE 平台实现——可以询问 Java SE Policy 以（几乎）对 Servlet 和 EJB 指定的任何类型的声明性安全约束进行可移植评估。我说几乎是因为 JACC 和 Policy#getPermissions(ProtectionDomain) 的 Javadoc 规范实际上都没有要求实现动态计算所有权限，大概是出于性能考虑，以及适应提供授权的提供者语句取决于附加上下文（远程地址、某个 HTTP GET 参数的值等）。尽管如此，getPermissions 与典型的预安装 JACC 提供程序一起使用通常应该是安全的。

以下示例演示了 Servlet 角色分配测试：

package com.example;

import java.security.CodeSource;
import java.security.Permission;
import java.security.PermissionCollection;
import java.security.Policy;
import java.security.Principal;
import java.security.ProtectionDomain;
import java.security.cert.Certificate;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;

import javax.security.auth.Subject;
import javax.security.jacc.PolicyContext;
import javax.security.jacc.PolicyContextException;
import javax.security.jacc.WebRoleRefPermission;

public final class Util {


    private static final Set<String> NO_ROLES = Collections.emptySet();
    private static final Permission DUMMY_WEB_ROLE_REF_PERM = new WebRoleRefPermission("", "dummy");

    /**
     * Retrieves the declared Servlet security roles that have been mapped to the {@code Principal}s of
     * the currently authenticated {@code Subject}, optionally limited to the scope of the Servlet
     * referenced by {@code servletName}.
     * 
     * @param servletName
     *            The scope; {@code null} indicates Servlet-context-wide matching.
     * @return the roles; empty {@code Set} iff:
     *         <ul>
     *         <li>the remote user is unauthenticated</li>
     *         <li>the remote user has not been associated with any roles declared within the search
     *         scope</li>
     *         <li>the method has not been called within a Servlet invocation context</li>
     *         </ul>
     */
    public static Set<String> getCallerWebRoles(String servletName) {
        // get current subject
        Subject subject = getSubject();
        if (subject == null) {
            // unauthenticated
            return NO_ROLES;
        }
        Set<Principal> principals = subject.getPrincipals();
        if (principals.isEmpty()) {
            // unauthenticated?
            return NO_ROLES;
        }
        // construct a domain for querying the policy; the code source shouldn't matter, as far as
        // JACC permissions are concerned
        ProtectionDomain domain = new ProtectionDomain(new CodeSource(null, (Certificate[]) null), null, null,
                principals.toArray(new Principal[principals.size()]));
        // get all permissions accorded to those principals
        PermissionCollection pc = Policy.getPolicy().getPermissions(domain);
        // cause resolution of WebRoleRefPermissions, if any, in the collection, if still unresolved
        pc.implies(DUMMY_WEB_ROLE_REF_PERM);
        Enumeration<Permission> e = pc.elements();
        if (!e.hasMoreElements()) {
            // nothing granted, hence no roles
            return NO_ROLES;
        }
        Set<String> roleNames = NO_ROLES;
        // iterate over the collection and eliminate duplicates
        while (e.hasMoreElements()) {
            Permission p = e.nextElement();
            // only interested in Servlet container security-role(-ref) permissions
            if (p instanceof WebRoleRefPermission) {
                String candidateRoleName = p.getActions();
                // - ignore the "any-authenticated-user" role (only collect it if your
                // application has actually declared a role named "**")
                // - also restrict to the scope of the Servlet identified by the servletName
                // argument, unless null
                if (!"**".equals(candidateRoleName) && ((servletName == null) || servletName.equals(p.getName()))
                        && ((roleNames == NO_ROLES) || !roleNames.contains(candidateRoleName))) {
                    if (roleNames == NO_ROLES) {
                        roleNames = new HashSet<>();
                    }
                    roleNames.add(candidateRoleName);
                }
            }
        }
        return roleNames;
    }

    private static Subject getSubject() {
        return getFromJaccPolicyContext("javax.security.auth.Subject.container");
    }

    @SuppressWarnings("unchecked")
    private static <T> T getFromJaccPolicyContext(String key) {
        try {
            return (T) PolicyContext.getContext(key);
        }
        catch (PolicyContextException | IllegalArgumentException e) {
            return null;
        }
    }

    private Util() {
    }

}

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参考资料：

• JSR-115 / JACC specification
• Using JACC to determine a caller's roles
• How Java EE translates web.xml constraints to Permission instances