春季3请求处理失败;嵌套的例外是显示java.lang.NullPointerException

Question

我有试图启动我的应用程序的困难

，我找我的错误了几天，但我在某处代码卡，并询问您的协助 感谢

SingleTransactionsController

@Controller 
public class SingleTransactionsController { 
private SingleTransactionsService singleTransactionsService; 


@RequestMapping(value="/disableUser/{sicil}", method=RequestMethod.GET) 
public String disableUser(@PathVariable String sicil, Model model){ 
    singleTransactionsService.disableUser(sicil); 
    model.addAttribute("message", sicil); 
    return "hello"; 
} 

} 

SingleTransactionsDAO

public interface SingleTransactionsDAO { 

public void disableUser(String sicil); 

} 

SingleTransactionsDAOImpl

@Repository 
public class SingleTransactionsDAOImpl implements SingleTransactionsDAO{ 

@Override 
public void disableUser(String sicil) { 
    System.out.println(sicil); 
} 
} 

SingleTransactionsService

public interface SingleTransactionsService { 
public void disableUser(String sicil); 
} 

SingleTransactionsServiceImpl

@Service 
public class SingleTransactionsServiceImpl implements SingleTransactionsService{ 

@Autowired 
private SingleTransactionsDAO singleTransactionsDAO; 


public void disableUser(String sicil) { 
    singleTransactionsDAO.disableUser(sicil); 

} 


public SingleTransactionsDAO getSingleTransactionsDAO() { 
    return singleTransactionsDAO; 
} 


public void setSingleTransactionsDAO(SingleTransactionsDAO singleTransactionsDAO) { 
    this.singleTransactionsDAO = singleTransactionsDAO; 
} 

MVC-调度员servlet.x毫升

<?xml version="1.0" encoding="UTF-8"?> 
<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:context="http://www.springframework.org/schema/context" 
    xmlns:mvc="http://www.springframework.org/schema/mvc" 
    xmlns:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx" 
    xsi:schemaLocation=" 
    http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.2.xsd 
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context-3.2.xsd 
    http://www.springframework.org/schema/mvc 
    http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd 
    http://www.springframework.org/schema/aop 
    http://www.springframework.org/schema/aop/spring-aop-3.2.xsd 
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx-3.2.xsd"> 

<context:annotation-config /> 
<mvc:resources mapping="/css/**" location="/css/" /> 
<mvc:resources mapping="/images/**" location="/images/" /> 
<!-- Load only @Controller annotated controllers --> 
<context:component-scan base-package="com.akbank.controller" 
    use-default-filters="false"> 
    <context:include-filter expression="org.springframework.stereotype.Controller" 
     type="annotation" /> 
</context:component-scan> 
<mvc:annotation-driven /> 

     <bean  class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"></bean> 
<bean  class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"> </bean> 

<bean 
    class="org.springframework.web.servlet.view.InternalResourceViewResolver"> 
    <property name="prefix"> 
     <value>/WEB-INF/pages/</value> 
    </property> 
    <property name="suffix"> 
     <value>.jsp</value> 
    </property> 
</bean> 
<bean id="singleTransactionsDAO" class="com.akbank.dao.SingleTransactionsDAOImpl"> </bean> 
<bean id="singleTransactionsService" class="com.akbank.service.SingleTransactionsServiceImpl"></bean> 

，当我尝试导航比如/ disableUser/Tugrul我得到以下错误：

HTTP Status 500 - Request processing failed; nested exception is  java.lang.NullPointerException 

type Exception report 

message Request processing failed; nested exception is java.lang.NullPointerException 

description The server encountered an internal error that prevented it from fulfilling  this request. 

exception 

org.springframework.web.util.NestedServletException: Request processing failed; nested  exception is java.lang.NullPointerException 
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.jav a:948) 
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:621) 
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 
root cause 

java.lang.NullPointerException 
com.akbank.controller.SingleTransactionsController.disableUser(SingleTransactionsCon troller.java:24) 
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25 ) 
java.lang.reflect.Method.invoke(Method.java:597) 
org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandle rMethod.java:219) 
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(Invoc ableHandlerMethod.java:132) 
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod. invokeAndHandle(ServletInvocableHandlerMethod.java:104) 
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.i nvokeHandleMethod(RequestMappingHandlerAdapter.java:745) 
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.h andleInternal(RequestMappingHandlerAdapter.java:686) 
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(Abstr actHandlerMethodAdapter.java:80) 
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java: 925) 
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:8 56) 
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.jav a:936) 
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:621) 
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.50  logs. 

我使用3.2.6.RELEASE版本

Answer 1

我想出了对我的问题的解决方案解决以下一个经过长期的研究是

控制器

@Resource(name = "singleTransactionsService") 
private SingleTransactionsService singleTransactionsService; 

SingleTransactionsServiceImpl

@Service("singleTransactionsService") 

通常情况下，答案应该是@Autowired注释，但它不起作用，虽然我用@Qualifier并命名了。希望解决方案可以帮助其他人在未来

Answer 2

此字段

private SingleTransactionsService singleTransactionsService; 

将保持null，您不在任何地方初始化它。

我相信你的意思是注入一个值，它

@Autowired 
private SingleTransactionsService singleTransactionsService;