mysql 中的 java.lang.NullPointerException

Question

我正在尝试建立我发现的网站 here ，当我运行该应用程序时，我得到

Error creating bean with name 'dataSource' defined in org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'getDataSource' threw exception; nested exception is java.lang.NullPointerException`

我查看了我的代码，问题似乎与应用程序未连接到数据库这一事实有关。当我尝试访问http://127.0.0.1:3306/paw时它只是告诉我该页面无法正常工作。

ds-hibernate-cfg.properties

# DataSource

ds.database-driver=com.mysql.jdbc.Driver
ds.url=jdbc:mysql://127.0.0.1:3306/paw
ds.username=root
ds.password=


# Hibernate Config

hibernate.dialect=org.hibernate.dialect.MySQLDialect
hibernate.show_sql=true
current_session_context_class=thread
hibernate.hbm2ddl.auto=update

ApplicationContextConfig.java

package org.o7planning.springmvcshoppingcart.config;

import java.util.Properties;

import javax.sql.DataSource;
import com.mysql.jdbc.Driver;

import org.hibernate.SessionFactory;
import org.o7planning.springmvcshoppingcart.dao.impl.AccountDAO;
import org.o7planning.springmvcshoppingcart.dao.impl.OrderDAO;
import org.o7planning.springmvcshoppingcart.dao.impl.ProductDAO;
import org.o7planning.springmvcshoppingcart.dao.impl.AccountDAOImpl;
import org.o7planning.springmvcshoppingcart.dao.impl.OrderDAOImpl;
import org.o7planning.springmvcshoppingcart.dao.impl.ProductDAOImpl;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.ResourceBundleMessageSource;
import org.springframework.core.env.Environment;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

@Configuration
@ComponentScan("org.o7planning.springmvcshoppingcart.*")
@EnableTransactionManagement
// Load to Environment.
@PropertySource("classpath:ds-hibernate-cfg.properties")
public class ApplicationContextConfig {

    // The Environment class serves as the property holder
    // and stores all the properties loaded by the @PropertySource

    private Environment env;

    @Bean
    public ResourceBundleMessageSource messageSource() {
        ResourceBundleMessageSource rb = new ResourceBundleMessageSource();
        // Load property in message/validator.properties
        rb.setBasenames(new String[] { "messages/validator" });
        return rb;
    }

    @Bean(name = "viewResolver")
    public InternalResourceViewResolver getViewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/pages/");
        viewResolver.setSuffix(".jsp");
        return viewResolver;
    }

    // Config for Upload.
    @Bean(name = "multipartResolver")
    public CommonsMultipartResolver multipartResolver() {
        CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();

        // Set Max Size...
        // commonsMultipartResolver.setMaxUploadSize(...);

        return commonsMultipartResolver;
    }

    @Bean(name = "dataSource")
    public DataSource getDataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();

        // See: ds-hibernate-cfg.properties
        dataSource.setDriverClassName(env.getProperty("ds.database-driver"));
        dataSource.setUrl(env.getProperty("ds.url"));
        dataSource.setUsername(env.getProperty("ds.username"));
        dataSource.setPassword(env.getProperty("ds.password"));

        System.out.println("## getDataSource: " + dataSource);

        return dataSource;
    }


    @Bean(name = "sessionFactory")
    public SessionFactory getSessionFactory(DataSource dataSource) throws Exception {
        Properties properties = new Properties();

        // See: ds-hibernate-cfg.properties
        properties.put("hibernate.dialect", env.getProperty("hibernate.dialect"));
        properties.put("hibernate.show_sql", env.getProperty("hibernate.show_sql"));
        properties.put("current_session_context_class", env.getProperty("current_session_context_class"));


        LocalSessionFactoryBean factoryBean = new LocalSessionFactoryBean();

        // Package contain entity classes
        factoryBean.setPackagesToScan(new String[] { "org.o7planning.springmvcshoppingcart.entity" });
        factoryBean.setDataSource(dataSource);
        factoryBean.setHibernateProperties(properties);
        factoryBean.afterPropertiesSet();
        //
        SessionFactory sf = factoryBean.getObject();
        System.out.println("## getSessionFactory: " + sf);
        return sf;
    }


    @Bean(name = "transactionManager")
    public HibernateTransactionManager getTransactionManager(SessionFactory sessionFactory) {
        HibernateTransactionManager transactionManager = new HibernateTransactionManager(sessionFactory);

        return transactionManager;
    }

    @Bean(name = "accountDAO")
    public AccountDAO getApplicantDAO() {
        return new AccountDAOImpl();
    }

    @Bean(name = "productDAO")
    public ProductDAO getProductDAO() {
        return new ProductDAOImpl();
    }

    @Bean(name = "orderDAO")
    public OrderDAO getOrderDAO() {
        return new OrderDAOImpl();
    }

    @Bean(name = "accountDAO")
    public AccountDAO getAccountDAO()  {
        return new AccountDAOImpl();


}

我的完整错误日志

SEVERE: Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'getDataSource' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1123)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1018)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4937)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'getDataSource' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588)
    ... 23 more
Caused by: java.lang.NullPointerException
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig.getDataSource(ApplicationContextConfig.java:72)
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig$$EnhancerBySpringCGLIB$$9065b576.CGLIB$getDataSource$1(<generated>)
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig$$EnhancerBySpringCGLIB$$9065b576$$FastClassBySpringCGLIB$$21772b0c.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:355)
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig$$EnhancerBySpringCGLIB$$9065b576.getDataSource(<generated>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)
    ... 24 more

May 25, 2017 8:41:08 PM org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'getDataSource' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1123)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1018)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4937)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'getDataSource' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588)
    ... 23 more
Caused by: java.lang.NullPointerException
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig.getDataSource(ApplicationContextConfig.java:72)
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig$$EnhancerBySpringCGLIB$$9065b576.CGLIB$getDataSource$1(<generated>)
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig$$EnhancerBySpringCGLIB$$9065b576$$FastClassBySpringCGLIB$$21772b0c.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:355)
    at org.o7planning.springmvcshoppingcart.config.ApplicationContextConfig$$EnhancerBySpringCGLIB$$9065b576.getDataSource(<generated>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)
    ... 24 more

Answer 1

从http://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/annotation/Configuration.html来看查看您的代码，您的 env 变量上可能缺少 @Inject 或 @Autowired 。我不确定是否可以保密。应该是:

@Inject Environment env;