我面对这个问题已经有好几天了,我认为,所有尝试都可以找到解决方案。我完全没有主意...
确定程序应执行的操作:输入用户名和密码后,程序应连接到数据库并检查输入的用户名/密码是否在该数据库中。由于sessionFactory的NullPointer,他从没有参加过此检查。
堆栈跟踪:
java.lang.NullPointerException
at de.mail.HibernateUtil.getSession(HibernateUtil.java:37)
at de.mail.gui.LoginServlet.doPost(LoginServlet.java:56)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:250)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
context.xml:
<!-- Component Scans -->
<context:component-scan base-package="de.mail" use-default-filters="false">
<context:include-filter type="annotation" expression="org.springframework.stereotype.Component" />
</context:component-scan>
<!-- Datenbank -->
<bean id="c3p0DataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
destroy-method="close">
<property name="driverClass" value="org.postgresql.Driver" />
<property name="jdbcUrl"
value="****" />
<property name="maxPoolSize" value="1" />
<property name="properties">
<props>
<prop key="user">postgres</prop>
<prop key="password">****</prop>
<prop key="characterEncoding">UTF-8</prop>
<!-- Properties sind nur notwendig, wenn man mal SSL für die DB-Verbindung
braucht (auch in der properties entkommentieren) -->
<!-- <prop key="ssl">${db.ssl}</prop> <prop key="sslfactory">${db.sslfactory}</prop> -->
</props>
</property>
</bean>
<alias name="c3p0DataSource" alias="dataSource" />
<!-- TransactionManager -->
<tx:annotation-driven transaction-manager="transactionManager" />
<bean id="transactionManager"
class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
<property name="nestedTransactionAllowed" value="true" />
</bean>
<!-- SessionFactory -->
<bean id="sessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean"
destroy-method="destroy">
<property name="dataSource" ref="dataSource" />
<property name="packagesToScan">
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</prop>
<prop key="hibernate.current_session_context_class">thread</prop>
<prop key="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.hbm2ddl.auto">update</prop>
</props>
</property>
<property name="annotatedPackages">
<list>
<value>de.mail</value>
<value>de.mail.data.dao</value>
<value>de.mail.vo</value>
<value>de.mail.gui</value>
</list>
</property>
<property name="annotatedClasses">
<list>
<value>de.mail.data.vo.UserVO</value>
<value>de.mail.data.vo.FilterVO</value>
<value>de.mail.data.vo.ResultVO</value>
<value>de.mail.data.dao.ActionDAO</value>
<value>de.mail.HibernateUtil</value>
<value>de.mail.FilterJob</value>
<value>de.mail.gui.ActionServlet</value>
<value>de.mail.gui.CreateServlet</value>
<value>de.mail.gui.DeleteServlet</value>
<value>de.mail.gui.EditServlet</value>
<value>de.mail.gui.FormServlet</value>
<value>de.mail.gui.InitServlet</value>
<value>de.mail.gui.LoginServlet</value>
<value>de.mail.gui.LogoutServlet</value>
<value>de.mail.gui.RegistrationServlet</value>
</list>
</property>
</bean>
HibernateUtil:
public abstract class HibernateUtil extends HttpServlet{
private static final long serialVersionUID = -1850678939342717642L;
@Autowired
private SessionFactory sessionFactory;
/**
* Gibt die derzeitige Session zurück
*
* @return derzeitige Session
* @throws HibernateException
*/
public Session getSession() {
/*try {
return sessionFactory.getCurrentSession();
} catch (Throwable e){
System.out.println("---> " + e);
return null;
}*/
return sessionFactory.getCurrentSession();
}
LoginServlet:
@Component
public class LoginServlet extends HibernateUtil {
/**
*
*/
private static final long serialVersionUID = -776218596462464850L;
private static final Log LOG = LogFactory.getLog(LoginServlet.class);
private static final int HEX_FF = 0xFF;
/**
* Bearbeitet den Loginversuch<br />
* Es werden die eingegebenen Daten ausgelesen. Aus dem Passwort wird ein Hash-Wert generiert, der mit dem Datenbankeintrag mit dem
* passenden Usernamen verglichen wird. Stimmt alles überein wird auf die main.jsp weitergeleitet. Im Fehlerfall wird zurück auf
* die login.jsp verwiesen.
*
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
* @param response der HttpResponse
* @param request der HttpRequest
* @throws ServletException ex
* @throws IOException ex
*/
@Override
@Transactional(propagation = Propagation.REQUIRES_NEW)
protected void doPost(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
if (!"Registrieren".equals(request.getParameter("register"))) {
final Session session = getSession();
// Generiert einen HashWert aus dem eingegebenen Passwort
try {
final byte[] pwBytes = request.getParameter("password").getBytes();
final MessageDigest algorithm = MessageDigest.getInstance("MD5");
algorithm.reset();
algorithm.update(pwBytes);
final byte[] messageDigest = algorithm.digest();
final StringBuffer hexString = new StringBuffer();
for (byte digest : messageDigest) {
hexString.append(Integer.toHexString(HEX_FF & digest));
}
final LoginDAO dao = new LoginDAO();
final List<UserVO> list = dao.checkLogin(request, session);
final UserVO userVO = list.get(0);
if (userVO.getPassword().equals(hexString.toString())) {
request.getSession().setAttribute("userid", userVO.getId());
final RequestDispatcher dispatcher = request.getRequestDispatcher("main.jsp");
dispatcher.forward(request, response);
} else {
final RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
dispatcher.forward(request, response);
}
} catch (NoSuchAlgorithmException nsax) {
LOG.debug("Keine MessageDigestSpi fuer den entsprechenden Alogrithmus gefunden");
} catch (NullPointerException npx) {
final RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
dispatcher.forward(request, response);
} catch (IndexOutOfBoundsException ioobx) {
final RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
dispatcher.forward(request, response);
}
} else {
final RequestDispatcher dispatcher = request.getRequestDispatcher("register.jsp");
dispatcher.forward(request, response);
}
}
/**
* Tut nix besonders. Leiet an die doPost-Methode weiter
*
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
* @param response der HttpResponse
* @param request der HttpRequest
* @throws ServletException ex
* @throws IOException ex
*/
@Override
protected void doGet(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
我真的没有在这里得到错误。我检查了每个文件,特别是在Spring上下文中是否缺少内容,但实际上什么也没发现。我认为该错误是由一些非常简单的原因引起的。对我来说-我是春天和冬眠的新手-不想发现错误。
您LoginServlet
有一个@Component
注释,它将使其成为spring托管的bean,但您的web.xml中也可能有一个servlet声明。现在,您有2个servlet实例,一个由spring管理(几乎没有用,因为否则就没有用),还有一个由Web容器管理的实例,该实例对容器没有任何作用@Autowired
。
要解决您的问题,请使用依赖项查找,而不是尝试进行依赖项注入。为此,请使用init
servlet的方法,并仅删除HibernateUtil
类和@Component
注释。
public class LoginServlet extends HttpServlet {
private SessionFactory sessionFactory;
public void init() {
ApplicationContext ctx = WebApplicationContext.getApplicationContext(getServletContext());
sessionFactory = ctx.getBean(SessionFactory.class);
}
protected Session getSession() {
return sessionFactory.getCurrentSession();
}
…
}
您@Transactional
永远都不会工作,因为bean不是春季管理的,注释基本上什么也没做。您可以通过将doPost
方法包装在中来解决此问题TransactionTemplate
。
<bean id="txTemplate" class="TransactionTemplate">
<constructor-arg ref="transactionManager" />
</bean>
然后在您的init
方法中为其添加查找
public class LoginServlet extends HttpServlet {
private TransactionTemplate txTemplate;
public void init() {
ApplicationContext ctx = WebApplicationContext.getApplicationContext(getServletContext());
…
txTemplate = ctx.getBean(TransactionTemplate.class);
}
将您的原始doPost
方法重命名为doPostInternal
(可选),private
并添加以下方法doPost
`
protected void doPost(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
txTemplate.execute(new TransactionCallbackWithoutResult() {
public void doInTransactionWithoutResult(TransactionStatus status) {
doPostInternal(request,response);
}
});
}
最后,当您使用时,您的休眠配置也存在缺陷hibernate.current_session_context_class
。使用spring时,除非使用JTA,否则应单独保留此属性。查看您的配置,您并不是要删除该属性的设置,因为当前设置会破坏与休眠之间的正确弹簧集成。
我强烈建议您查看整体架构,因为您当前的设计存在缺陷。您拥有一个取决于Web层的dao层(它与有关HttpServletRequest
)。您正在尝试将抽shoe弹簧插入非基于弹簧的应用程序中(您可以如上所述进行工作,但使用spring更容易)。将代码移至Controller
并进行适当修改LoginDao
将改善您的总体体系结构。这也将使测试变得更加容易(没有更多的Web依赖项)。
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