Spring Web 应用程序 - java.lang.NullPointerException 与 jdbcTemplate

Question

我正在使用 jdbcTemplate 编写一个简单的 spring 3.0 Restful Webservice 但每次我尝试访问资源时都会收到 java.lang.NullPointerException 。

我创建了一个像这样的 DAO

public interface MisCodeDao {

    public void setDataSource(DataSource ds);
//the remaining method declarations
    }
}

我的 DAOImpl 看起来像这样

public class MisCodeDAOImp implements MisCodeDao {
private JdbcTemplate jdbcTemplate;
    public void setDataSource(DataSource dataSource) {
    this.jdbcTemplate = new JdbcTemplate(dataSource);
    }
public List<MisCode> findAll() throws MisCodeDAOException {
    if(this.jdbcTemplate==null)
    {
    System.out.print("JDBC TEMPLATE IS NULL");
    }
    return (List<MisCode>) this.jdbcTemplate.query("SELECT misCode, misClass, codeDesc, active from miscode", new RowMapper<MisCode>() {
    public MisCode mapRow(ResultSet resultSet, int row) throws SQLException {
    MisCode miscode = new MisCode();
    miscode.setMisCode(resultSet.getString("misCode"));
    System.out.print(resultSet.getString("misCode"));
    miscode.setMisClass(resultSet.getString("misClass"));
    miscode.setCodeDesc(resultSet.getString("codeDesc"));
    String charValueStr=resultSet.getString("active"); 
    miscode.setActive(charValueStr.charAt(0));
    return miscode;
        }
    });


}

这是我的 application-context.xml 的样子

<?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:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/util/spring-util-3.0.xsd">
<bean id="propertyConfigurer"
      class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
      p:location="/WEB-INF/jdbc.properties" />

<bean id="dataSource"
      class="org.springframework.jdbc.datasource.DriverManagerDataSource"
      p:driverClassName="${jdbc.driver}"
      p:url="${jdbc.url}"
      p:username="${jdbc.username}"
      p:password="${jdbc.password}" />

<bean id="misCodeDAO" class="com.tavia.bacponline.DaoImpl.MisCodeDAOImp">
   <property name="dataSource" ref="dataSource"/>
</bean>
</beans>

完整的堆栈 strace 在这里：

WARNING: StandardWrapperValve[bacponline]: PWC1406: Servlet.service() for servlet bacponline threw exception
java.lang.NullPointerException
    at com.tavia.bacponline.DaoImpl.MisCodeDAOImp.findAll(MisCodeDAOImp.java:67)
    at com.tavia.bacponline.controller.MisCodeController.getMisCodes(MisCodeController.java:45)
    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:174)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:421)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:409)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
    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:734)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:619)

这是我的控制器：

@Controller
public class MisCodeController {
private Jaxb2Marshaller jaxb2Mashaller;
    public void setJaxb2Mashaller(Jaxb2Marshaller jaxb2Mashaller) {
    this.jaxb2Mashaller = jaxb2Mashaller;
}
private static final String XML_VIEW_NAME = "miscodes";
private MisCodeDAOImp miscodeImpl = new MisCodeDAOImp();

@RequestMapping(method=RequestMethod.GET, value="/miscodes")
public ModelAndView getMisCodes() throws MisCodeDAOException {
List<MisCode> miscodes = miscodeImpl.findAll();
MisCodeList list = new MisCodeList(miscodes);
return new ModelAndView(XML_VIEW_NAME, "miscodes", list);
}
}

我的 web.xml 看起来像这样

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
id="WebApp_ID" version="2.5">

<display-name>com.tavia.bacponline</display-name>
<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/bacponline-context.xml</param-value>
</context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
    <servlet-name>bacponline</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>bacponline</servlet-name>
    <url-pattern>/service/*</url-pattern>
</servlet-mapping>
<session-config>
    <session-timeout>
        30
    </session-timeout>
</session-config>
<welcome-file-list>
    <welcome-file>redirect.jsp</welcome-file>
</welcome-file-list>
</web-app>

谢谢

Answer 1

我可能在你的帖子中遗漏了一些东西...但是这里是...

1. 控制器是基于注释的，请在应用程序上下文文件中向 spring 指示相同的内容。.还可以使用

2. 而不是使用

private MisCodeDAOImp MiscodeImpl = new MisCodeDAOImp( ）；

使用以下内容进行自动装配

@Autowire
private MisCodeDAOImp miscodeImpl;

由于您已经在应用程序上下文文件中定义了 bean，因此它应该自动装配。