Question

进入Spring几周后，我遇到了 NoSuchBeanDefinitionException 。试图在这里找到解决其他问题的解决方案，但没有运气。尝试在Eclipse中启动我的简单Spring应用程序时出现此错误：

aug 29, 2015 7:33:45 PM org.springframework.context.support.ClassPathXmlApplicationContext refresh
WARNING: Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'offersDao': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire method: public void by.blabla.spring.test.OffersDAO.setDataSource(javax.sql.DataSource); nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [javax.sql.DataSource] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}

我使用@Autowired注释在OffersDAO.java中只有一个依赖注入。实现DataSource接口的BasicDataSource bean在beans.xml配置文件中定义，但我的应用程序无法以某种方式连接到它。

配置文件 beans.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:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">

    <context:annotation-config></context:annotation-config>

    <context:component-scan base-package="by.blabla.spring.test"></context:component-scan>

    <context:property-placeholder location="by/blabla/spring/props/jdbc.properties" />

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
        destroy-method="close">
        <property name="driverClassName" value="${jdbc.driver}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="password" value="${jdbc.password}"></property>
        <property name="username" value="${jdbc.username}"></property>
    </bean>

</beans>

主要应用程序文件 App.java ：

package by.blabla.spring.test;

import java.util.List;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App {

    public static void main(String[] args) {

        ApplicationContext context = new ClassPathXmlApplicationContext("by/blabla/spring/test/beans/beans.xml");

        OffersDAO offersDao = (OffersDAO)context.getBean("offersDao");

        List<Offer> list = offersDao.getOffers();

        for(Offer offer : list){
            System.out.println(offer);
        }

        ((ClassPathXmlApplicationContext)context).close();
    }
}

OffersDAO.java ：

package by.blabla.spring.test;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Component;

@Component("offersDao")
public class OffersDAO {

    private JdbcTemplate jdbc;

    @Autowired
    public void setDataSource(DataSource jdbc) {
        this.jdbc = new JdbcTemplate(jdbc);
    }

    public List<Offer> getOffers() {

        return jdbc.query("select * from offers", new RowMapper<Offer>() {

            public Offer mapRow(ResultSet rs, int rowNum) throws SQLException {
                Offer offer = new Offer();
                offer.setId(rs.getInt("id"));
                offer.setName(rs.getString("name"));
                offer.setEmail(rs.getString("email"));
                offer.setText(rs.getString("text"));

                return offer;
            }
        });
    }
}

Answer 1

在你的dao类中，ter不是使用DataSource类型声明的属性。 IOC尝试列出要使用Reflection注入的属性，但它找不到bean配置文件中提到的名称和类型的参数

您的代码应如下

@Component("offersDao") 
public class OffersDAO {
 private JdbcTemplate jdbc;
 private DataSource datasource;
  @Autowired public void setDataSource(DataSource ds) { 
this.datasource=ds;
this.jdbc = new JdbcTemplate(ds); 
}

建议：最好在spring上下文中创建ur jdbc模板并注入它而不是注入数据源并创建模板对象......

Answer 2

试试这个：

@Component("offersDao")
public class OffersDao implements InitializingBean {

private JdbcTemplate jdbc;

@Autowired
private DataSource dataSource;

@Override
public void afterPropertiesSet() throws Exception {
    this.jdbc = new JdbcTemplate(this.dataSource);
}

public List<Offer> getOffers() {

    return jdbc.query("select * from offers", new RowMapper<Offer>() {

        public Offer mapRow(ResultSet rs, int rowNum) throws SQLException {
            Offer offer = new Offer();
            offer.setId(rs.getInt("id"));
            offer.setName(rs.getString("name"));
            offer.setEmail(rs.getString("email"));
            offer.setText(rs.getString("text"));

            return offer;
        }
    });
}
}

（Java Spring）NoSuchBeanDefinitionException：找不到[javax.sql.DataSource]类型的限定bean

2 个答案: