无法自动装配 - org.springframework.beans.factory.BeanCreationException

Question

我正在尝试使用 Spring Boot、Maven 和 Tomcat 构建一个宁静的 Web 服务。

当我尝试将 maven jar 文件部署到 Tomcat 时，我收到此错误：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'selectConfRoomController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.jdbc.core.JdbcTemplate hello.SelectConfRoomController.jt; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.jdbc.core.JdbcTemplate] 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)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:293)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1186)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:706)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:762)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:109)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:320)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:952)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:941)
at hello.Application.main(Application.java:14)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:53)
at java.lang.Thread.run(Unknown Source)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.jdbc.core.JdbcTemplate hello.SelectConfRoomController.jt; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.jdbc.core.JdbcTemplate] 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)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:509)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:290)
    ... 22 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.jdbc.core.JdbcTemplate] 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)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1118)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:967)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:862)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:481)
    ... 24 common frames omitted

我的 application.properties 文件位于包 src/main/resources 中

spring.datasource.url=jdbc:jtds:sqlserver://***
spring.datasource.username=***
spring.datasource.password=***
spring.datasource.driverClassName=net.sourceforge.jtds.jdbc.Driver

src/main/java

Application.java

package hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan
@EnableAutoConfiguration
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

查询中...

package hello;

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

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController 
public class SelectConfRoomController extends JdbcTemplate{

    @Autowired
    private JdbcTemplate jt;

    @RequestMapping(value="/", method=RequestMethod.GET)
    public List<Region> getRegions(){

        String sql = "SELECT OUID_Region, RegionName FROM Region";
        List <Region> rows = jt.query(sql, 
                new RowMapper<Region>(){
            @Override
            public Region mapRow(ResultSet rs, int rowNum) throws SQLException {
                return new Region(rs.getLong("OUID_Region"), rs.getString("RegionName"));
            }
        });

        System.out.println("querying regions");
        return rows; 
    }

}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>***</groupId>
    <artifactId>webservice-test</artifactId>
    <version>1</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.1.7.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
    </dependencies>

    <properties>
        <start-class>hello.Application</start-class>
        <java.version>1.8</java.version>
    </properties>

    <build>
      <finalName>ConfRoom</finalName>
        <plugins>
           <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
       </plugins>
    </build>

    <repositories>
        <repository>
            <id>spring-releases</id>
            <url>http://repo.spring.io/libs-release</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-releases</id>
            <url>http://repo.spring.io/libs-release</url>
        </pluginRepository>
    </pluginRepositories>
</project>

阅读this 中的解决方案，我觉得我不需要xml 文件。有人能找到我不知道的错误吗？我对这一切都很陌生，所以任何专业知识/指导都将不胜感激。

Answer 1

尝试用JdbcTemplate声明一个bean

@Bean
public DataSource getDataSource(){
    /* Return the data source with proper configuration... */
}


@Autowired
public DataSource dataSource;



@Bean
public JdcTemplate getJdbcTemplate(){
    JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
    return dataSource;
}

Answer 2

我认为，问题在于您扩展了 JdbcTemplate。如果没有找到具有此类型的其他 bean，则 Spring Boot 仅创建一个 JdbcTemplate。但是您的类是 JdbcTemplate 类型的 bean，因此 JdbcTemplate 的自动配置被跳过。尝试删除“扩展 JdbcTemplate”，您的课程似乎不需要它。

Answer 3

您需要在上下文 xml 中指定 JDBCTemplate，如下所示，或者您需要添加组件扫描包。

http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/context/annotation/ComponentScan.html

 <bean id="jtDataSource"
      class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="*******"/>
    <property name="url" value="*******"/>
    <property name="username" value="*****"/>
    <property name="password" value="**********"/>
 </bean>
 <bean id="jt" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="jtDataSource"/> --Incase if you are configuring data source
 </bean>