spring注解装配出现的空指针问题，急求啊

Question

本帖最后由 u010571601 于 2014-06-11 12:31:49 编辑

Answer 1

报如下错误严重: Servlet.service() for servlet [jsp] in context with path [/springtest] threw exception [java.lang.NullPointerException] with root cause
java.lang.NullPointerException
at bean.studentService.getInfo(studentService.java:16)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:97)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2441)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2430)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)

Answer 2

public class studentService {
    @Resource
    student student;
     
    public studentService()
    {
    }
    public String getInfo()
    {
        student.setName("小强");
        student.setMajor("计算机科学与技术专业");
        return student.toString();
    }
 
}这个类是你自己new出来的，不是spring管理的，spring怎么给你注入？

Answer 3

那你在java代码里怎么用你装配的bean呢？？就这么直接用吗？
ApplicationContext context=new FileSystemXmlApplicationContext("src/applicationContext.xml");
        student student=context.getBean("student",student.class);

Answer 4

既然配置好了，可以直接用呀：
ApplicationContextAware aca = (ApplicationContextAware) context.getBean("applicationContextUtils"); // save this context instance to utils

Answer 5

你说的很对，我用ctx.getbean得到的studentservice实例里面的student确实被注入了，我还有一个问题，把struts2和spring整合到一起的时候，action类中用@resource也能实现自动装配是怎么回事？？难道这时候action类就自动交由spring管理了吗？

Answer 6

你说的很对，我用ctx.getbean得到的studentservice实例里面的student确实被注入了，我还有一个问题，把struts2和spring整合到一起的时候，action类中用@resource也能实现自动装配是怎么回事？？难道这时候action类就自动交由spring管理了吗？正确

Answer 7

你的思路有错误 ， 建议 再看下 Spring   注解方面的文档