Java Spring IoC-依赖项注入->NullPointerException
我有这样的结构: 接口IProjectService,由ProjectServiceImpl实现 现在我有了一个控制器,我想在其中使用依赖项注入:Java Spring IoC-依赖项注入->NullPointerException,java,spring,dependency-injection,Java,Spring,Dependency Injection,我有这样的结构: 接口IProjectService,由ProjectServiceImpl实现 现在我有了一个控制器,我想在其中使用依赖项注入: @Controller @RequestMapping(value="/testFolder") public class MyDIController { ... private IProjectService projectServiceImpl; public void setProjectServiceImpl(IP
@Controller
@RequestMapping(value="/testFolder")
public class MyDIController {
...
private IProjectService projectServiceImpl;
public void setProjectServiceImpl(IProjectService projectServiceImpl) {
this.projectServiceImpl= projectServiceImpl;
}
...
@RequestMapping(value="/project", method=RequestMethod.GET)
public @ResponseBody Project getProject() {
Project project = this.projectServiceImpl.getProject(12); // line 37! (id 12 is a test case, it does exist, here is he error: this.projectServiceImpl = null)
return project;
}
}
在applicationContext.xml中,我有以下几行代码:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="projectServiceImpl" class="com.mydomain.project.service.impl.ProjectServiceImpl" />
<bean id="projectService" class="com.mydomain.project.service.IProjectService">
<property name="projectServiceImpl">
<ref local="projectServiceImpl"/>
</property>
</bean>
</beans>
问题是
this.projectServiceImpl
为null,因此依赖项注入似乎不起作用
这里怎么了,有人知道吗
向蒂姆问好
更新:
完整错误跟踪:
09.12.2010 11:16:53 org.apache.catalina.core.ApplicationDispatcher invoke
SCHWERWIEGEND: Servlet.service() for servlet project threw exception
java.lang.NullPointerException
at com.mydomain.project.controller.MyDIController.getAllProjects(MyDIController.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:195)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:159)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)
09.12.2010 11:16:53 org.apache.catalina.core.StandardWrapperValve invoke
SCHWERWIEGEND: Servlet.service() for servlet default threw exception
java.lang.NullPointerException
at com.mydomain.project.controller.MyDIController.getProject(MyDIController.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:195)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:159)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)
`
applicationContext.xml:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="projectService" class="com.mydomain.project.service.impl.ProjectServiceImpl" />
<bean id="myDIController" class="com.mydomain.project.controller.MyDIController">
<property name="projectServiceImpl">
<ref local="projectService"/>
</property>
</bean>
</beans>
web.xml:
<servlet>
<servlet-name>project</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/app-config.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
app-config.xml:
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<!-- Scans the classpath of this application for @Components to deploy as beans -->
<context:component-scan base-package="com.mydomain.project" />
<!-- Application Message Bundle -->
<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basename" value="/WEB-INF/messages/messages" />
<property name="cacheSeconds" value="0" />
</bean>
<!-- Configures Spring MVC -->
<import resource="mvc-config.xml" />
</beans>
你没有;MyDIController的t注入属性projectServiceImpl 应该是
<bean id="projectService" class="com.mydomain.project.service.impl.ProjectServiceImpl" />
<bean id="myDIController " class="com.mydomain.project.service.MyDIController">
<property name="projectServiceImpl">
<ref local="projectService"/>
</property>
</bean>
在web.xml中
<web-app>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/application-context.xml
</param-value>
</context-param>
.
.
.
.
<servlet>
.
.
.
你没有;MyDIController的t注入属性projectServiceImpl 应该是
<bean id="projectService" class="com.mydomain.project.service.impl.ProjectServiceImpl" />
<bean id="myDIController " class="com.mydomain.project.service.MyDIController">
<property name="projectServiceImpl">
<ref local="projectService"/>
</property>
</bean>
在web.xml中
<web-app>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/application-context.xml
</param-value>
</context-param>
.
.
.
.
<servlet>
.
.
.
你有几个选择 为控制器声明一个XMLBean,并在其中设置服务的属性。 根据您的Spring版本,使用Spring的注释/自动布线支持。
如果选择数字2,请确保在xml配置中包含,并为projectService属性用@controller和@Autowired标记控制器类。您有几个选项 为控制器声明一个XMLBean,并在其中设置服务的属性。 根据您的Spring版本,使用Spring的注释/自动布线支持。
如果你选择2号,请确保在您的xml配置中包含并使用@controller和@Autowired为您的projectService属性标记控制器类。如何获取控制器实例?微小变量命名提示:不要命名接口类型为*Impl…的变量。使用implementation@LiviuT:好的,在这个问题解决后,我会改变这个。如何获得控制器的实例?微小变量命名提示:不要命名接口类型为*Impl的变量…使用implementation@LiviuT:好的,这个问题解决后,我会更改它。@Bozho他没有在controller中注入服务,服务也应该在contextah中引用它的impl,是的。。他甚至还没有映射控制器。我仍然得到相同的错误:Servlet.service for Servlet项目在=this.projectServiceImpl.getProject12的行中抛出了异常java.lang.NullPointerException@Tim你是如何获得myDIController实例的?@Tim它将以这种方式工作,因为现在你的容器正在从应用程序上下文读取bean,但更好的做法是这样做,就像服务bean应该在另一个上下文文件中,控制器在不同的上下文文件中,你应该使用,干杯:@Bozho他没有在controller中注入服务,服务也应该在contextah中引用它的impl,是的。。他甚至还没有映射控制器。我仍然得到相同的错误:Servlet.service for Servlet项目在=this.projectServiceImpl.getProject12的行中抛出了异常java.lang.NullPointerException@Tim你是如何获得myDIController实例的?@Tim它将以这种方式工作,因为现在你的容器正在从应用程序上下文读取bean,但更好的做法是这样做,就像服务bean应该在另一个上下文文件中,控制器在不同的上下文文件中一样,你应该使用,干杯: