Question

我将从我的项目结构开始。

enter image description here

SpecialClaimsCaseManager.java - 发生错误的地方：

package com.redacted.sch.web.mvc.model;

//Some imports that don't matter

@Component
public class SpecialClaimsCaseManager {

    @Autowired
    private SpecialClaimsCaseRepositoryService<SpecialClaimsCaseDto> specialClaimsCaseRepositoryService;

    public Collection<SpecialClaimsCase> findAll() {
        return convertToSpecialClaimsCase(specialClaimsCaseRepositoryService.findAll()); //Error happens here. specialClaimsCaseRepositoryService is null
    }

//Some irrelevant code finishing up the class

SpecialClaimsCaseRespositoryService - 需要注入的类的接口：

package com.redacted.sch.service;

public interface SpecialClaimsCaseRepositoryService<C extends SpecialClaimsCaseDto> {
    //Some irrelevant interface code
}

SpecialClaimsCaseRepositoryServiceImpl - 实现接口的类。这是应该注入的。

package com.redacted.sch.service.impl;

@Service 
public class SpecialClaimsCaseRepositoryServiceImpl implements SpecialClaimsCaseRepositoryService<SpecialClaimsCaseDto> {

    @Autowired
    private SpecialClaimsCaseRepository repository; //This autowire actually works. Not relevant to the problem, though.

    //Some code...
}

ApplicationController - Controller显然

package com.redacted.web.mvc.controllers;

//Some imports

@Controller
public class ApplicationController {

        @RequestMapping(value="/test", method=RequestMethod.GET)
        public @ResponseBody Collection<SpecialClaimsCase> getCaseInJSON(@RequestParam Map<String, String> requestParams, ModelMap model) {
            SpecialClaimsCaseManager caseManager = new SpecialClaimsCaseManager();

            return new ArrayList<SpecialClaimsCase>(caseManager.findAll());
        }
}

现在进入配置，我们将从web.xml开始：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <display-name>SpecialClaimsHandling</display-name>

    <!-- Spring Configuration Files -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            WEB-INF/applicationContext.xml
            WEB-INF/application-security.xml
            classpath*:sch_model_spring.xml
        </param-value>
    </context-param>

    <!-- Spring Security Filters -->
    <filter>
        <filter-name>springSecurityFilterChain</filter-name>
        <filter-class>
             org.springframework.web.filter.DelegatingFilterProxy
        </filter-class>
    </filter>

    <filter-mapping>
        <filter-name>springSecurityFilterChain</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- Spring Listeners -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- MVC Filter -->
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>

    <!-- Session Configuration -->
    <session-config>
        <session-timeout>5</session-timeout>
    </session-config>

</web-app>

和dispatcher-servlet.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"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
            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">

    <context:component-scan base-package="com.redacted.sch.web.mvc.controllers"/>

    <mvc:resources mapping="/resources/**" location="/resources/" />

    <mvc:annotation-driven />

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
       <property name="prefix" value="/WEB-INF/views/" />
       <property name="suffix" value=".jsp" />
    </bean>

</beans>

的applicationContext.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"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
            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">

    <context:component-scan base-package="com.redacted.sch.web.mvc.controllers"/>

    <mvc:resources mapping="/resources/**" location="/resources/" />

    <mvc:annotation-driven />

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
       <property name="prefix" value="/WEB-INF/views/" />
       <property name="suffix" value=".jsp" />
    </bean>

</beans>

最后是sch_model_spring.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"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

        <context:component-scan base-package="com.redacted.repository.jpa,
              com.redacted.sch.domain.model,
              com.redacted.sch.repository.jpa,
              com.redacted.sch.service,
              com.redacted.sch.service.impl"/>

        <tx:annotation-driven />

        <tx:jta-transaction-manager />

        <!-- Data source used for testing -->
        <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
            <property name="driverClassName" value="com.ibm.db2.jcc.DB2Driver" />
            <property name="url" value="redacted.doesntmatter.com" />
            <property name="username" value="redacted" />
            <property name="password" value="redacted" />
        </bean>

        <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
              <property name="persistenceUnitName" value="schManager" />
              <property name="dataSource" ref="dataSource" />
        </bean>

        <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
            <property name="entityManagerFactory" ref="entityManagerFactory" />
        </bean> 
</beans>

好的，所以在配置文件，类和结构的墙之后，让我们解决问题。在SpecialClaimsCaseManager我有@Autowired SpecialClaimsCaseRepositoryService<SpecialClaimsCaseDto>对象，实际上没有连线。当它被使用时，抛出的NPE是以下堆栈跟踪：

（此处简称，通过fpaste提供全部内容）

[7/10/14 15:20:13:343 CDT] 000000fe webapp        E com.ibm.ws.webcontainer.webapp.WebApp logServletError SRVE0293E: [Servlet Error]-[dispatcher]: java.lang.NullPointerException
    at com.redacted.sch.web.mvc.model.SpecialClaimsCaseManager.findAll(SpecialClaimsCaseManager.java:26)
    at com.redacted.sch.web.mvc.controllers.ApplicationController.getCaseInJSON(ApplicationController.java:43)
    ........

从我以前的帮助中收集到的，这是一个上下文问题。 SpecialClaimsCaseManager所在的上下文无法访问SpecialClaimsCaseRepositoryService。我不知道为什么会这样，或者如何解决它。我已经完成了项目并将其重构为我认为可以工作的项目，但仍然没有运气。我真的被困在这里，不知道如何解决这个问题。

非常感谢您的帮助。如果还有其他需要，请询问。

Answer 1

你使用new运算符的那一刻它不是Spring管理的。

将您的控制器更改为：

    @Controller
    public class ApplicationController {
            @Autowired
            SpecialClaimsCaseManager caseManager;

            @RequestMapping(value="/test", method=RequestMethod.GET)
            public @ResponseBody Collection<SpecialClaimsCase> getCaseInJSON(@RequestParam Map<String, String> requestParams, ModelMap model) {
                ....
                return new ArrayList<SpecialClaimsCase>(caseManager.findAll());
            }
    }

Answer 2

可能是你的classpath def在web.xml中出错吗？

classpath*:sch_model_spring.xml

我也会使用类似的东西：

classpath:/spring/beans-datasource.xml

Spring @Autowired Bean NullPointerException - 没有连线

2 个答案: