java 在 spring 中创建带有名称的 bean 时出错

Error creating bean with name in spring

提问by springnoob

(Spring newbie so apologies in advance for any obvious errors) Trying to create a authentication page using Spring. Get the following error:

（对于任何明显错误，Spring 新手提前道歉）尝试使用 Spring 创建身份验证页面。得到以下错误：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'JDBCLoginDAOImpl': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private javax.sql.DataSource org.project.shoppingcart.dao.jdbc.JDBCLoginDAOImpl.dataSource; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [javax.sql.DataSource] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    org.springframework.beans.factory.support.AbstractBeanFactory.getObject(AbstractBeanFactory.java:294)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
    org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
    org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
    org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:631)
    org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:588)
    org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:645)
    org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:508)
    org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:449)
    org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:133)
    javax.servlet.GenericServlet.init(GenericServlet.java:160)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    com.springsource.insight.collection.tcserver.request.HttpRequestOperationCollectionValve.invoke(HttpRequestOperationCollectionValve.java:84)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
    org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
    java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    java.lang.Thread.run(Thread.java:680)

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Here is my app-context.xml:

这是我的 app-context.xml：

<?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:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <description>Example configuration to get you started.</description>

    <context:annotation-config /> 
    <context:component-scan base-package="org.project.shoppingcart" />
    <context:component-scan base-package="org.project.shoppingcart." />

    <context:property-placeholder location="classpath:jdbc.properties"/>

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driver_class}" />
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
    </bean>

    <bean id="txManager"
        class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource" />
    </bean>

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" lazy-init="true">
        <property name="dataSource" ref="dataSource" />
    </bean>

</beans>

=======

========

Here is my JDBCLoginDAOImpl.java:

这是我的 JDBCLoginDAOImpl.java：

@Repository
public class JDBCLoginDAOImpl implements LoginDao {

    @Autowired
    private DataSource dataSource;

    private SimpleJdbcTemplate jdbcTemplate;

    @PostConstruct
    public void setup() {
        jdbcTemplate = new SimpleJdbcTemplate(dataSource);
    }

    public boolean validateUser(String Username, String Password) {
        int count = 0;
        String query = "select count(*) from products where username = "+Username+
                "and password = "+Password;
        count = jdbcTemplate.queryForInt(query);
        if (count > 0) {
            return true;
        }
        else {
            return false;
        }
    }
}

回答by Sean Patrick Floyd

Your setup looks almost correct to me, the only bothersome bit I can find is this:

你的设置对我来说几乎是正确的，我能找到的唯一麻烦的是：

<context:component-scan base-package="org.project.shoppingcart" />
<context:component-scan base-package="org.project.shoppingcart." />

This is a double component scan, I am pretty sure the above two statements are equal (at least they both match sub packages of shoppingcart, possible they also both match shoppingcart). Anyway, you are creating several beans multiple times. I'd start by cleaning that up (lose one of them) and perhaps your problem will go away.

这是一个双组件扫描，我很确定上面的两个语句是相等的（至少它们都匹配购物车的子包，可能它们也都匹配购物车）。无论如何，您正在多次创建多个 bean。我首先清理它（丢失其中一个），也许你的问题会消失。

回答by victorpacheco3107

change

改变

@Autowired
private DataSource dataSource;

by:

经过：

@Autowired
private DriverManagerDataSource dataSource;

and add the import:

并添加导入：

import org.springframework.jdbc.datasource.DriverManagerDataSource;

导入 org.springframework.jdbc.datasource.DriverManagerDataSource;

and adjust the getter and setter

并调整 getter 和 setter