java.lang.NullPointerException，出了什么问题？

Question

当我验证表单中的登录名和密码时，出现此错误java.lang.NullPointerException。但我不知道出了什么问题，因为我已经搜索了相同的错误消息，似乎我的代码中的某些内容正在发送 Null 值。

LoginAction.java:

package com.tutorialspoint.struts2.action;

import java.util.Hashtable;

import javax.naming.Context;
import javax.naming.NamingEnumeration;
import javax.naming.directory.Attribute;
import javax.naming.directory.SearchControls;
import javax.naming.directory.SearchResult;
import javax.naming.ldap.InitialLdapContext;
import javax.naming.ldap.LdapContext;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.opensymphony.xwork2.ActionContext;
import com.tutorialspoint.struts2.UserProfile;

public class LoginAction extends BaseAction {

    /**
     * Serial Version UID
     */
    private static final long serialVersionUID = 1L;

    private String login;
    private String pass;

    private static Log logger = LogFactory.getLog(LoginAction.class);

    public String execute() {
        boolean auth = false;

        UserProfile userProfile = new UserProfile();
        String token = getLogin() + "#" + getPass();



        String searchFilter = "(&(objectClass=user)(sAMAccountName="
                + getLogin() + "))";
        SearchControls searchCtls = new SearchControls();
        searchCtls.setSearchScope(SearchControls.SUBTREE_SCOPE);

        String domain = getApplicationGlobal().getaDURI();
        domain = domain.substring(domain.indexOf(".") + 1);

        Hashtable<String, String> env = new Hashtable<String, String>();
        env.put(Context.INITIAL_CONTEXT_FACTORY,
                "com.sun.jndi.ldap.LdapCtxFactory");
        env.put(Context.PROVIDER_URL, getApplicationGlobal().getaDURI());
        env.put(Context.SECURITY_AUTHENTICATION, "simple");
        env.put(Context.SECURITY_PRINCIPAL, getLogin() + "@" + domain);
        env.put(Context.SECURITY_CREDENTIALS, pass);

        try {
            LdapContext ctx = new InitialLdapContext(env, null);
            NamingEnumeration sr = ctx.search(getApplicationGlobal()
                    .getaDBaseDN(), searchFilter, searchCtls);

            while (sr.hasMoreElements()) {
                SearchResult r = (SearchResult) sr.next();
                logger.debug("LDAP Info:" + r.getNameInNamespace());
                Attribute members = r.getAttributes().get("memberOf");
                logger.debug("LDAP Number of Group for this user:"
                        + members.size());
                NamingEnumeration<String> emembers = (NamingEnumeration<String>) members
                        .getAll();
                while (emembers.hasMore()) {
                    String ldapGroup = emembers.next();
                    String myLdapGroup = getFirstLdapValue(ldapGroup, null);
                    logger.debug("LDAP Group:" + myLdapGroup);
                    if (myLdapGroup != null) {
                        myLdapGroup = myLdapGroup.toLowerCase();
                        if (myLdapGroup.equals(getApplicationGlobal()
                                .getaDGroupeAdmin().toLowerCase())) {
                            userProfile.setAdmin(true);
                        } else if (myLdapGroup.equals(getApplicationGlobal()
                                .getaDGroupeSuperviseur().toLowerCase())) {
                            userProfile.setSuperviseur(true);

                        } else if (myLdapGroup.equals(getApplicationGlobal()
                                .getaDGroupeUser().toLowerCase())) {
                            userProfile.setUser(true);

                        }
                    }
                }
            }
        } catch (Exception e) {
            // throw new
            // FunctionalException(FunctionalException.AUTHENTICATION_ERROR, e,
            // ERROR);
            logger.info("ERREUR: " + e);
        }

        // on ne retient que les roles "utiles"
        if (userProfile.getIsAdmin()) {
            logger.info("L'utilisateur " + login + " est admin");
            userProfile.setSuperviseur(false);
            userProfile.setUser(false);
            auth = true;
        } else {
            if (userProfile.getIsSuperviseur()) {
                logger.info("L'utilisateur " + login + " est superviseur");
                userProfile.setUser(false);
                auth = true;
            } else {
                if (!userProfile.isUser()) {
                    logger.info("ERREUR: L'utilisateur " + login
                            + " n'est pas user");
                } else {
                    auth = true;
                    logger.info("L'utilisateur " + login + " est user");
                }
            }
        }
        if (auth) {
            userProfile.setLogin(getLogin());
            ActionContext.getContext().getSession()
                    .put(getApplicationGlobal().getUserProfile(), userProfile);
            ActionContext.getContext().getSession()
                    .put(getApplicationGlobal().getToken(), token);
            logger.warn("AD Authentification SUCCESS!");
            return SUCCESS;
        } else {
            logger.warn("AD Authentification FAILED!!!");
            return "notLogged";
        }

    }


    private String getFirstLdapValue(final String ldapCsvValues,
            final Integer position) {
        String myLdapCsvValues = ldapCsvValues;
        Integer myPosition = position;
        if (position == null) {
            myPosition = 0;
        }
        if (myLdapCsvValues == null) {
            return null;
        }
        myLdapCsvValues = myLdapCsvValues.replace("\\,", "");
        String values[] = myLdapCsvValues.split(",");
        String value0[] = values[myPosition].split("=");
        return value0[1];
    }


    public String getLogin() {
        return login;
    }

    public void setLogin(String login) {
        this.login = login;
    }

    public String getPass() {
        return pass;
    }

    public void setPass(String pass) {
        this.pass = pass;
    }

}

struts.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
   "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
   "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
<constant name="struts.enable.DynamicMethodInvocation" value="false" />
<constant name="struts.devMode" value="true" />


<package name="main"  namespace="/" extends="struts-default">
        <result-types>
            <result-type name="tiles" class="org.apache.struts2.views.tiles.TilesResult" />
        </result-types>

      <action name="Accueil">
            <result >/baseLayout.jsp</result>

      </action>

        <action name="Accueil" class="com.opensymphony.xwork2.ActionSupport">
             <result name="success" type="tiles">accueil</result>
        </action>

    <action name="Login" class="com.tutorialspoint.struts2.action.LoginAction">
            <result name="success" type="redirectAction">HelloWorld.jsp</result>
            <result name="notLogged" type="tiles">notLogged.tiles</result>
        </action>






   </package>
</struts>

控制台:

2015-02-11 10:44:22,872 DEBUG com.opensymphony.xwork2.config.ConfigurationManager.debug:57 - Checking ConfigurationProviders for reload.
2015-02-11 10:44:22,873 DEBUG com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler.debug:57 - Entering nullPropertyValue [target=[com.opensymphony.xwork2.DefaultTextProvider@9267d9], property=struts]
2015-02-11 10:44:22,873 DEBUG com.opensymphony.xwork2.config.ConfigurationManager.debug:57 - Checking ConfigurationProviders for reload.
2015-02-11 10:44:22,874 DEBUG com.opensymphony.xwork2.DefaultActionProxy.debug:57 - Creating an DefaultActionProxy for namespace / and action name Login
2015-02-11 10:44:22,874 DEBUG com.opensymphony.xwork2.interceptor.I18nInterceptor.debug:57 - intercept '//Login' { 
2015-02-11 10:44:22,874 DEBUG com.opensymphony.xwork2.interceptor.I18nInterceptor.debug:57 - applied invocation context locale=fr_FR
2015-02-11 10:44:22,875 DEBUG com.opensymphony.xwork2.interceptor.I18nInterceptor.debug:57 - before Locale=fr_FR
2015-02-11 10:44:22,875 DEBUG com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler.debug:57 - Entering nullPropertyValue [target=[com.tutorialspoint.struts2.action.LoginAction@590bf4, com.opensymphony.xwork2.DefaultTextProvider@9267d9], property=struts]
2015-02-11 10:44:22,876 DEBUG org.apache.struts2.interceptor.FileUploadInterceptor.debug:57 - Bypassing //Login
2015-02-11 10:44:22,876 DEBUG com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.debug:57 - Setting static parameters {}
2015-02-11 10:44:22,876 DEBUG com.opensymphony.xwork2.interceptor.ParametersInterceptor.debug:57 - Setting params NONE
2015-02-11 10:44:22,877 DEBUG com.opensymphony.xwork2.interceptor.ParametersInterceptor.debug:57 - Setting params login => [ test1 ] pass => [ test2 ] 
2015-02-11 10:44:22,877 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - Property: login
2015-02-11 10:44:22,877 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - Class: com.tutorialspoint.struts2.action.LoginAction
2015-02-11 10:44:22,878 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - field-level type converter for property [login] = none found
2015-02-11 10:44:22,878 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - global-level type converter for property [login] = none found
2015-02-11 10:44:22,878 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - falling back to default type converter [com.opensymphony.xwork2.conversion.impl.XWorkBasicConverter@1adfb84]
2015-02-11 10:44:22,879 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - Property: pass
2015-02-11 10:44:22,879 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - Class: com.tutorialspoint.struts2.action.LoginAction
2015-02-11 10:44:22,880 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - field-level type converter for property [pass] = none found
2015-02-11 10:44:22,880 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - global-level type converter for property [pass] = none found
2015-02-11 10:44:22,880 DEBUG com.opensymphony.xwork2.conversion.impl.XWorkConverter.debug:57 - falling back to default type converter [com.opensymphony.xwork2.conversion.impl.XWorkBasicConverter@1adfb84]
2015-02-11 10:44:22,881 DEBUG org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.debug:57 - Validating //Login with method execute.
2015-02-11 10:44:22,894 DEBUG com.opensymphony.xwork2.validator.ValidationInterceptor.debug:57 - Invoking validate() on action com.tutorialspoint.struts2.action.LoginAction@590bf4
2015-02-11 10:44:22,895 DEBUG com.opensymphony.xwork2.interceptor.PrefixMethodInvocationUtil.debug:57 - cannot find method [validateExecute] in action [com.tutorialspoint.struts2.action.LoginAction@590bf4]
2015-02-11 10:44:22,895 DEBUG com.opensymphony.xwork2.interceptor.PrefixMethodInvocationUtil.debug:57 - cannot find method [validateDoExecute] in action [com.tutorialspoint.struts2.action.LoginAction@590bf4]
2015-02-11 10:44:22,896 DEBUG com.opensymphony.xwork2.DefaultActionInvocation.debug:57 - Executing action method = null
2015-02-11 10:44:22,896 DEBUG com.opensymphony.xwork2.config.ConfigurationManager.debug:57 - Checking ConfigurationProviders for reload.

错误消息:

    Struts Problem Report

    Struts has detected an unhandled exception:

    Messages:   
    File:   com/tutorialspoint/struts2/action/LoginAction.java
    Line number:    59

--------

Stacktraces

java.lang.NullPointerException (...)

如果您需要其他文件或详细信息，请告诉我!

感谢任何帮助!

Answer 1

我认为 NamingEnumeration sr 可能存在问题。如果它为 null 或空，则在此变量上调用 while 循环将返回空指针异常。至少我已经经历过几次这样的事情了。我建议调试您的代码并查看哪个变量出现异常。希望这有帮助:)