java.lang.NullPointerException。 是否是Spring配置的问题？ 谢谢！

Question

java.lang.NullPointerException。 是否是Spring配置的问题？ 谢谢！    sturts里的DAO对象为null!!! 急急急 !!

Answer 1

DAO是注入的吗，是的话估计就是配错了啊

Answer 2

dao 实例、 manage 实例等需要注入的东西没有被注入

Answer 3

很有可能是这样
看看你的sessionfactory有没有配置好，有没有注入dao

Answer 4

action-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"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<bean name="/swanInfo" class="com.music.struts.action.SwanInfoAction"
abstract="false" lazy-init="default" autowire="default"
dependency-check="default">
<property name="swanInfoManager">
<ref bean="swanInfoManager" />
</property>
</bean>
<bean name="/user" class="com.music.struts.action.UserAction"
abstract="false" lazy-init="default" autowire="default"
dependency-check="default">
<property name="swanInfoManager">
<ref bean="swanInfoManager" />
</property>
</bean>
</beans>

Answer 5

struts-config.xml<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd">
<struts-config>
<data-sources />
<form-beans>
<form-bean name="swanInfoForm" type="com.music.struts.form.SwanInfoForm" />
<form-bean name="uesrInfoForm" type="com.music.struts.form.UesrInfoForm" />
    <form-bean name="userForm" type="com.music.struts.form.UserForm" />
</form-beans>
<global-exceptions />
<global-forwards />
<action-mappings>
<action attribute="swanInfoForm" input="/swanInfo.jsp" name="swanInfoForm"
parameter="method" path="/swanInfo" scope="request"
type="org.springframework.web.struts.DelegatingActionProxy" validate="false"/>
<action attribute="uesrInfoForm" input="/uesrInfo.jsp" name="uesrInfoForm"
path="/uesrInfo" scope="request"
type="org.springframework.web.struts.DelegatingActionProxy" validate="false"/>
    <action
      attribute="userForm"
      input="/user.jsp"
      name="userForm"
      path="/user"
      scope="request"
      type="com.music.struts.action.UserAction" />
</action-mappings>
<message-resources parameter="com.music.struts.ApplicationResources" />
<plug-in className="org.springframework.web.struts.ContextLoaderPlugIn">
<set-property property="contextConfigLocation" value="/WEB-INF/applicationContext.xml" />
</plug-in>
</struts-config>

Answer 6

web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.5" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <context-param>
    <param-name>ContextConfigLocation</param-name>
    <param-value>/WEB-INF/applicationContext.xml</param-value>
  </context-param>
  <filter>
    <filter-name>EncodingFilter</filter-name>
    <filter-class>com.music.util.EncodingFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>EncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
    <init-param>
      <param-name>debug</param-name>
      <param-value>3</param-value>
    </init-param>
    <init-param>
      <param-name>detail</param-name>
      <param-value>3</param-value>
    </init-param>
    <load-on-startup>0</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <login-config>
    <auth-method>BASIC</auth-method>
  </login-config>
</web-app>

Answer 7

大侠，NullPointerException和Spring 二者既不充分也不必要
完全是两个东西，一个是空指针异常，一个是开源框架。NullPointerException说直白点，就是你对为NULL的参数没有判断就直接做一些操作，如：get(),set(),save()......根据这个思路，相信你可以解决了。