spring mvc jadbc webapp中的自动装配bean失败答案

【问题标题】：autowiring bean failed in spring mvc jadbc webappspring mvc jadbc webapp中的自动装配bean失败
【发布时间】：2015-11-03 09:20:08
【问题描述】：

我正在学习使用弹簧。我正在使用 spring 和 jdbc 开发应用程序。我在运行时遇到以下异常。

Nov 03, 2015 2:42:22 PM org.apache.catalina.core.ApplicationContext log
SEVERE: StandardWrapper.Throwable
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'studentController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.dao.StudentDaoImp com.controller.StudentController.studentDaoImp; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'studentDaoImp' defined in file [C:\Users\Mrunal\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\SpringMVC\WEB-INF\classes\com\dao\StudentDaoImp.class]: Bean instantiation via constructor failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.dao.StudentDaoImp]: Constructor threw exception; nested exception is java.lang.IllegalArgumentException: Property 'dataSource' is required
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1210)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:663)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:629)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:677)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:548)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:489)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
    at javax.servlet.GenericServlet.init(GenericServlet.java:158)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5253)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5543)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.StandardContext.reload(StandardContext.java:4020)
    at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:425)
    at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1344)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1545)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1555)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1555)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1523)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.dao.StudentDaoImp com.controller.StudentController.studentDaoImp; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'studentDaoImp' defined in file [C:\Users\Mrunal\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\SpringMVC\WEB-INF\classes\com\dao\StudentDaoImp.class]: Bean instantiation via constructor failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.dao.StudentDaoImp]: Constructor threw exception; nested exception is java.lang.IllegalArgumentException: Property 'dataSource' is required
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:561)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
    ... 31 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'studentDaoImp' defined in file [C:\Users\Mrunal\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\SpringMVC\WEB-INF\classes\com\dao\StudentDaoImp.class]: Bean instantiation via constructor failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.dao.StudentDaoImp]: Constructor threw exception; nested exception is java.lang.IllegalArgumentException: Property 'dataSource' is required
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:275)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1139)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1042)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1120)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1044)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533)
    ... 33 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.dao.StudentDaoImp]: Constructor threw exception; nested exception is java.lang.IllegalArgumentException: Property 'dataSource' is required
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:163)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:122)
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:267)
    ... 45 more
Caused by: java.lang.IllegalArgumentException: Property 'dataSource' is required
    at org.springframework.jdbc.support.JdbcAccessor.afterPropertiesSet(JdbcAccessor.java:135)
    at org.springframework.jdbc.core.JdbcTemplate.<init>(JdbcTemplate.java:169)
    at com.dao.StudentDaoImp.<init>(StudentDaoImp.java:18)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147)
    ... 47 more

我的调度器 servlet 看起来像

<!-- declaring base package -->
<context:component-scan base-package="com" />

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



<!-- declare datasource bean -->
<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.microsoft.sqlserver.jdbc.SQLServerDriver" />
    <property name="url"
        value="jdbc:sqlserver://localhost:49155;databaseName=Test;instancename=mssqlserver1;" />
    <property name="username" value="sa" />
    <property name="password" value="abc123" />
</bean>

<bean id="StudentDao" class="com.dao.StudentDaoImp" >
<constructor-arg ref="dataSource" />
</bean>

and my controller class looks like
public class StudentDaoImp {

@Autowired
DataSource dataSource; 

JdbcTemplate jdbcTemplateObject = new JdbcTemplate(dataSource);  

@Autowired
public StudentDaoImp(DataSource dataSource)
{
    this.dataSource = dataSource;
}


public void create(String name, Integer age) {
    String SQL = "insert into Student (name, age) values (?, ?)";

    jdbcTemplateObject.update( SQL, name, age);
    System.out.println("Created Record Name = " + name + " Age = " + age);
    return;
}


public Student getStudent(Integer id) {
    String SQL = "select * from Student where id = ?";
    Student student = jdbcTemplateObject.queryForObject(SQL, 
            new Object[]{id}, new StudentMapper());
    return student;
}

}

我尝试了很多选项，但我无法找到错误。有人知道答案吗？

【问题讨论】：

你不应该需要那些 @Autowired 注释，因为你在 xml 配置中明确定义了依赖关系。
我尝试删除 @autowired 注释，但如果我删除它，它不会给出 StudentDaoImp 这样的方法
严重：Web 应用程序 [/SpringMVC] 中的 Servlet [spring] 抛出 load() 异常 java.lang.NoSuchMethodException: com.dao.StudentDaoImp.()

标签： java spring jdbc datasource

【解决方案1】：

问题解决了。

由于此声明而造成问题 JdbcTemplate jdbcTemplateObject = new JdbcTemplate(dataSource);

实例变量在构造函数之前初始化，因此它将空变量传递给数据源。

我关注了

   JdbcTemplate jdbcTemplateObject;
@Autowired
public StudentDaoImp(DataSource dataSource)
{
this.dataSource = dataSource;
jdbcTemplateObject = new JdbcTemplate(this.dataSource); 
}

【讨论】：