java - 我正在尝试 Spring MVC，当我在 Controller 类中添加 @Autowired 时，出现以下错误 :

Question

<beans
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:c="http://www.springframework.org/schema/c"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:util="http://www.springframework.org/schema/util"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd">

    <context:component-scan base-package="com.packt.webstore.domain" />
    <context:annotation-config></context:annotation-config>

    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource" >
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://localhost:3306/Webstore"></property>
        <property name="username" value="root"></property>
        <property name="password" value="password"></property>
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
        <property name="dataSource" ref="dataSource" />
    </bean>
</beans>

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'productController': Unsatisfied dependency expressed through field 'productRepository'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'productRepositoryImpl': Unsatisfied dependency expressed through method 'setDataSource' parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'javax.sql.DataSource' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}

package com.packt.webstore.domain.repository.impl;

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

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
import org.springframework.stereotype.Repository;

import com.packt.webstore.domain.Product;
import com.packt.webstore.domain.repository.ProductRepository;

@Repository
public class ProductRepositoryImpl implements ProductRepository {

    private NamedParameterJdbcTemplate jdbcTemplate;

    @Autowired
    private void setDataSource(DataSource dataSource) {
        this.jdbcTemplate=new NamedParameterJdbcTemplate(dataSource);
    }

    @Override
    public List<Product> getAllProducts() {
        Map<String, Object>params=new HashMap<String,Object>();
        List<Product>result=jdbcTemplate.query("SELECT * FROM PRODUCTS", params, new ProductMapper());
        return result;
    }

    private static final class ProductMapper implements org.springframework.jdbc.core.RowMapper<Product> {
        public Product mapRow(ResultSet rs,int rownum) throws SQLException{
            Product product=new Product();
            product.setName(rs.getString("name"));
            return product;
        }
    }
}

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

    <mvc:annotation-driven enable-matrix-variables="true"></mvc:annotation-driven>

    <context:component-scan base-package="com.packt"/>

     <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" 
     p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" />
</beans>

package com.packt.webstore.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import com.packt.webstore.domain.repository.ProductRepository;

@Controller
public class ProductController {

    @Autowired
    private ProductRepository productRepository;


    @RequestMapping("/products")
    public String list(Model model) {
        model.addAttribute("products",productRepository.getAllProducts());
        return "products";
    }
}

Answer 1

看起来您没有在 xml 文件中配置data-source

尝试在xml文件中添加以下配置

<bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">

        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/yourdbname" />
        <property name="username" value="root" />
        <property name="password" value="password" />
    </bean>