Question

SSH集成时action里的service接口总是为null，最后执行到操作数据库时出现空指针异常。而自己写测试类能成

<bean id="StaffDAO" class="com.jyx.dao.StaffDAO">
<property name="sessionFactory">
<ref bean="sessionFactory" />
</property>
</bean>

<!-- <property name="istaffService" ref="istaffService"/> -->
<bean id="istaffService" class="com.jyx.service.impl.StaffService">
<property name="staffDAO" ref="StaffDAO"/>
</bean>

<bean id="loginAction" class="com.jyx.struts.action.LoginAction" scope="prototype">
<property name="istaffService">
<ref bean="istaffService"/>
</property>
</bean>

最后控制台出现空指针异常:

严重: Servlet.service() for servlet action threw exception
java.lang.NullPointerException
at com.jyx.service.impl.StaffService.findByExample(StaffService.java:27)
at com.jyx.struts.action.LoginAction.execute(LoginAction.java:48)
at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
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.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)

//action的loginForm中是可以得到值的，只是其service接口一直为null。

Answer 1

你把那个接口的初始化去掉试试，你在bean里都定义好了接口的实现，所以我觉得是不是可以不用

追问

去掉初始化也不行，还是之前的错误，没去掉可以进DAO，去掉了DAO也进不了。