我有两个服务类和一个存储库类。当我尝试将一个服务bean自动装配到另一个服务bean时，会注入一个bean。但是当我尝试调用该方法时，它会显示NullPointerException。请帮帮我。在过去的3天里，我一直坚持这一点。
我的第一个服务类：
@Service
public class MetaData implements MetaDataService {
private AffiliateRepository util;
@Autowired
public MetaData(AffiliateRepository util) {
this.util = util;// I can see bean getting injected
}
public boolean findByEmail() {
// some logic
}
}
我的第二个服务类：
@Service
public class ResetPasswordForm implements ResetPasswordFormService {
public ResetPasswordForm() {
}
private MetaDataService md;
@Autowired
public ResetPasswordForm(MetaDataService md) {
this.md = md; // when iam debugging I could see bean got injected at this point.
}
public void advancedValidation(Map<String, String> errors) {
else if (id.contains("@") && md.findByEmail())// when iam calling method present in class using md it is showing md is null {
}
}
}
我的存储库类：
@Repository
public class JpaAffiliate implements AffiliateRepository, Serializable {
private EntityManagerFactory emf;
@PersistenceUnit(unitName="resetpwd-unit")
public void setEntityManagerFactory(EntityManagerFactory emf) {
this.emf = emf;
}
@SuppressWarnings("unchecked")
public List<Affiliate> findAffiliate(String value) {
// calls to database
}
}
我已尝试过所有内容（例如<context:component-scan base-package>指向我的基础包）。可能是什么问题？
下面是我的完整堆栈跟踪
ResetPasswordForm.java:134) [classes:]
at (ResetPasswordForm.java:119) [classes:]
at ...resetpwd.web.Page.getPage(Page.java:38) [classes:]
at ....web.ResetPasswordController.addContact(ResetPasswordController.java:52) [classes:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_55]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_55]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_55]
at java.lang.reflect.Method.invoke(Method.java:606) [rt.jar:1.7.0_55]
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219) [spring-web-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) [spring-web-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:754) [jboss-servlet-api_3.0_spec-1.0.2.Final-redhat-1.jar:1.0.2.Final-redhat-1]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) [spring-webmvc-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.2.Final-redhat-1.jar:1.0.2.Final-redhat-1]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:295) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) [spring-web-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:246) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) [spring-web-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:246) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) [spring-web-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-3.2.6.RELEASE.jar:3.2.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:246) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:149) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:169) [jboss-as-web-7.3.0.Final-redhat-14.jar:7.3.0.Final-redhat-14]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:145) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:97) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:102) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:336) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:488) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.coyote.ajp.AjpProtocol$AjpConnectionHandler.process(AjpProtocol.java:420) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:920) [jbossweb-7.2.2.Final-redhat-1.jar:7.2.2.Final-redhat-1]
at java.lang.Thread.run(Thread.java:745) [rt.jar:1.7.0_55]
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"版本=＆＃34; 3.0＆＃34;＆GT;
我的web.xml文件
<description>resetpwd Web Application</description>
<display-name>resetpwd</display-name>
<filter>
<filter-name>hiddenHttpMethodFilter</filter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>hiddenHttpMethodFilter</filter-name>
<servlet-name>resetpwd</servlet-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>resetpwd</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath*:spring/servlet-context.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>resetpwd</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>forceEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- uncomment JPA support persistence unit configuration below -->
<persistence-unit-ref>
<persistence-unit-ref-name>persistence/resetpwd-unit</persistence-unit-ref-name>
<persistence-unit-name>resetpwd-unit</persistence-unit-name>
</persistence-unit-ref>
<persistence-context-ref>
<persistence-context-ref-name>persistence/resetpwd-context</persistence-context-ref-name>
<persistence-unit-name>resetpwd-unit</persistence-unit-name>
</persistence-context-ref>
<!-- uncomment JPA support persistence unit configuration above -->
<welcome-file-list>
<welcome-file>welcome.jsp</welcome-file>
<welcome-file>welcome.html</welcome-file>
<welcome-file>index.html</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
这里是servlet-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<!--
DispatcherServlet context for applications web tier
-->
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:security="http://www.springframework.org/schema/security"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/security
http://www.springframework.org/schema/security/spring-security.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/jee
http://www.springframework.org/schema/jee/spring-jee.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<security:debug/>
<import resource="servlet-view.xml"/>
<context:component-scan base-package="edu.ucsd.act.core.resetpwd" />
<!-- turns on support for mapping requests to Spring MVC @Controller methods. also registers default Formatters and validators for use across all @Controllers -->
<mvc:annotation-driven conversion-service="conversionService"/>
<!-- all resources (css,js,jpg,png,bmp) inside folder (src/main/webapp/resources) are mapped so they can be referred to inside JSP files (see header.jsp for more details) -->
<mvc:resources mapping="/resources/**" location="/resources/"/>
<bean id="expressionHandler" class="edu.ucsd.act.core.coresecurity.requiresaction.MethodExpressionHandler" />
<!-- static case, no java controller needed -->
<mvc:view-controller path="/" view-name="welcome" />
<!-- serve all static resources (*.html,...) from src/main/webapp/ -->
<mvc:default-servlet-handler/>
<!-- [J] customized -->
<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
<!-- [1] remove default formatters -->
<property name="registerDefaultFormatters" value="false" />
<!-- [2] establish exact formatters that are desired -->
<property name="formatters">
<set>
<bean class="org.springframework.format.number.NumberFormatAnnotationFormatterFactory" />
<!-- add additional business formatters here -->
</set>
</property>
<!-- [3] alter formatter to match your business requirement -->
<property name="formatterRegistrars">
<set>
<bean class="org.springframework.format.datetime.joda.JodaTimeFormatterRegistrar">
<property name="dateFormatter">
<bean class="org.springframework.format.datetime.joda.DateTimeFormatterFactoryBean">
<property name="pattern" value="yyyyMMdd"/>
</bean>
</property>
</bean>
</set>
</property>
</bean>
<!--
- Message source for this context, loaded from localized "messages_xx" files.
- Files are stored inside src/main/resources
-->
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource" p:basename="messages/messages" p:fallbackToSystemLocale="false"/>
<!-- [J] register "global" interceptor beans to apply to all registered HandlerMappings -->
<mvc:interceptors>
<bean class="org.springframework.web.servlet.theme.ThemeChangeInterceptor"/>
<bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor" p:paramName="lang"/>
</mvc:interceptors>
<!-- [J] store preferred language configuration in a cookie -->
<bean class="org.springframework.web.servlet.i18n.CookieLocaleResolver" id="localeResolver" p:cookieName="locale"/>
<!-- [J] resolves localized <theme_name>.properties files in the classpath to allow for theme support, store configuration in a cookie
<bean class="org.springframework.ui.context.support.ResourceBundleThemeSource" id="themeSource"/>
<bean class="org.springframework.web.servlet.theme.CookieThemeResolver" id="themeResolver" p:cookieName="theme" p:defaultThemeName="standard"/>
-->
<!-- This bean resolves specific types of exceptions to corresponding logical - view names for error views. The default behavior of
DispatcherServlet - is to propagate all exceptions to the servlet container: this will happen - here with all other types of exceptions. -->
<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<!-- view name resolved using bean of type InternalResourceViewResolver (declared in servlet-view.xml) -->
<property name="defaultErrorView" value="exception"/>
<!-- results into 'WEB-INF/views/exception.jsp' -->
<property name="warnLogCategory" value="warn"/>
<property name="exceptionMappings">
<props>
<!-- spring security -->
<prop key="org.springframework.security.access.AccessDeniedException">/403</prop>
</props>
</property>
</bean>
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver">
<property name="order" value="1"/>
</bean>
<bean class="org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver" >
<property name="order" value="2"/>
</bean>
<!-- developer may wish to further customize final exception handler -->
<bean class="edu.ucsd.act.core.resetpwd.util.AppHandlerExceptionResolver">
<property name="order" value="3"/>
</bean>
<!-- Enable this for eventual integration of file upload functionality
<bean class="org.springframework.web.multipart.commons.CommonsMultipartResolver" id="multipartResolver" />
-->
<tx:annotation-driven mode="aspectj"
transaction-manager="transactionManager" />
<bean id="app" class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/>
<jee:jndi-lookup id="resetpwd-unit" jndi-name="persistence/resetpwd-unit" />
</beans>
public Map<String, String> validate() throws IOException {
advancedValidation(errors);
}
public void advancedValidation(Map<String, String> errors) {
if (!id.contains("@") && md.findByRacf()) {
// found a unique affiliate based on racf (may be primary or
// secondary)
} else if (id.contains("@") && md.findByEmail()) {
// found a unique affiliate based on email
} else {
// a unique affiliate record could not be located
errors.put("id", "resetpw.nouiserinfo");
return;
}
答案 0 :(得分：1)
您已在ResetPasswordForm课程中声明了两个构造函数。可能，Spring-container可能为同一个类with parameter创建了一个重复的实例，而另一个类default constructor创建了一个重复的实例。尝试删除默认构造函数创建。它应该工作。
答案 1 :(得分：0)
我只想到一种可能的解释：你加载了多个上下文，并且你实际上有两个不同的bean实例，其中NPE出现 - 一个带有注入的依赖，一个没有它（导致NPE）。
答案 2 :(得分：0)
试试这个。只要你保持一致，这种范式就有效：
@Service
public class MetaData implements MetaDataService {
public boolean findByEmail() {
this.affiliateRepository.someMethod();
// some logic
}
//I like to autowire at the bottom - keep all the glamour up front
@Autowired
private AffiliateRepository affiliateRepository;
}
您的其他服务：
@Service
public class ResetPasswordForm implements ResetPasswordFormService {
public ResetPasswordForm() {}
public void advancedValidation(Map<String, String> errors) {
if (someJunk) {
}
else if (id.contains("@") && metaData.findByEmail()) {
}
else {
}
}
//your ORM, if you have one, may complain if this is an interface
@Autowired
private MetaData metaData;
}
我通常不会使用EntityManager（我使用SessionFactory），但我想象它会是这样的：
@Repository
@Transactional
public class AffiliateRepositoryImpl implements AffiliateRepository, Serializable {
@PersistenceContext
private EntityManager entityManager;
@SuppressWarnings("unchecked")
@Transactional(readOnly = true, timeout = 10)
public List<Affiliate> findAffiliate(String value) {
// calls to database
}
}
您应该检查persistence.xml以确保使用持久性单元正确defined。