Servlet，不满足依赖，无此类Bean定义异常如何解决？

Question

我是 Spring 新手，我刚刚启动了一个 Spring MVC CRUD 程序，但在尝试了多种方法后，我一次又一次面临相同的错误。

这是打印 HTTP 状态 500 – 内部服务器错误的第一个异常。

ServletException

javax.servlet.ServletException: Servlet.init() for servlet [dispatcher] threw exception
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:687)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1732)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
    org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Unknown Source)

不满足的依赖性

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'appController': Unsatisfied dependency expressed through field 'studentService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.springmvc.student.configuration.service.StudentService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:659)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639)
    org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:953)
    org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918)
    org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583)
    org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:702)
    org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:578)
    org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:530)
    org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:170)
    javax.servlet.GenericServlet.init(GenericServlet.java:158)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:687)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1732)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
    org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Unknown Source)

NoSuchBean

org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.springmvc.student.configuration.service.StudentService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1799)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1355)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1309)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:656)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639)
    org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:953)
    org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918)
    org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583)
    org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:702)
    org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:578)
    org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:530)
    org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:170)
    javax.servlet.GenericServlet.init(GenericServlet.java:158)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:687)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1732)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
    org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Unknown Source)

Pom

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.java.spring</groupId>
    <artifactId>student-application-MVC</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>student-application-MVC Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.15</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>5.3.15</version>
        </dependency>
        <!-- Hibernate -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.3.6.Final</version>
        </dependency>
        <!-- jsr303 validation -->
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>1.1.0.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.3.6.Final</version>
        </dependency>

        <!-- MySQL -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.16</version>
        </dependency>

        <!-- Servlet+JSP+JSTL -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <warSourceDirectory>src/main/webapp</warSourceDirectory>
                    <warName>student-application-MVC</warName>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
        </plugins>
        <finalName>student-application-MVC</finalName>
    </build>
</project>

我也更改了依赖版本，但仍然无法正常工作是我的代码

配置类

package com.springmvc.student.configuration;

import org.springframework.context.MessageSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ResourceBundleMessageSource;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages="com.springmvc.student")
public class MyAppConfig {

    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setViewClass(JstlView.class);
        viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");
        return viewResolver;
    }

    @Bean
    public MessageSource messageSource() {
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        messageSource.setBasename("messages");
        return messageSource;
    }

}

配置初始化器

 package com.springmvc.student.configuration;
    
    import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
    
    public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    
        @Override
        protected Class<?>[] getRootConfigClasses() {
    
            return null;
        }
    
        @Override
        protected Class<?>[] getServletConfigClasses() {
    
            return new Class[] { MyAppConfig.class };
        }
    
        @Override
        protected String[] getServletMappings() {
            
            return new String[] { "/" };
        }
    
    }

我 数据库配置

package com.springmvc.student.configuration;

import java.util.Properties;
import javax.sql.DataSource;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
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;

@Configuration
@EnableTransactionManagement // Used to enable transactional support: Annotations can be recognized by spring
                                // container
@PropertySource(value = { "classpath:application.properties" })
public class DatabaseConfig {

     @Autowired
     private Environment environment;
    
    @Bean
    @Autowired
    public HibernateTransactionManager transactionManager(SessionFactory s) {
        HibernateTransactionManager txManager = new HibernateTransactionManager();
        txManager.setSessionFactory(s);
        return txManager;
    }

    // @Bean
    public DataSource dataSource() {// Declare information of DB connection by using a Datasource
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(environment.getRequiredProperty("jdbc.driver"));
        dataSource.setUrl(environment.getRequiredProperty("jdbc.url"));
        dataSource.setUsername(environment.getRequiredProperty("jdbc.username"));
        dataSource.setPassword(environment.getRequiredProperty("jdbc.password"));
        return dataSource;
    }

    private Properties hibernateProperties() {
        Properties properties = new Properties();
        properties.put("hibernate.dialect", environment.getRequiredProperty("hibernate.dialect"));
        properties.put("hibernate.show_sql", environment.getRequiredProperty("hibernate.show_sql"));
        properties.put("hibernate.format_sql", environment.getRequiredProperty("hibernate.format_sql"));
        return properties;
    }

    @Bean(name = "sessionFactory")
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
        sessionFactory.setDataSource(dataSource());
        sessionFactory.setPackagesToScan("com.spring.student.model");
        sessionFactory.setHibernateProperties(hibernateProperties());
        return sessionFactory;
    }

}

我使用 Hibernate For Database

模型类

package com.springmvc.student.configuration.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "student_hub")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column(name = "fistName", nullable = false)
    private String firstName;
    @Column(name = "lastName", nullable = false)
    private String lastName;
    @Column(name = "grades", nullable = false)
    private Integer grade;

    public Student() {
        super();
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public Integer getGrade() {
        return grade;
    }

    public void setGrade(Integer grade) {
        this.grade = grade;
    }

    @Override
    public String toString() {
        return "Student [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", grade=" + grade + "]";
    }

}

服务类 服务类

package com.springmvc.student.configuration.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;

import com.springmvc.student.configuration.DAO.StudentDao;
import com.springmvc.student.configuration.model.Student;

public class StudentServiceImpl implements StudentService {

    @Autowired
    private StudentDao studentDao;

    public Student getStudent(Long id) {

        return studentDao.getStudent(id);
    }

    public Long saveStudent(Student std) {

        return studentDao.saveStudent(std);
    }

    public List<Student> listAllStudent() {

        return studentDao.listAllStudent();
    }

    public void update(Long id, Student std) {

        Student stEntity = studentDao.getStudent(id);
        if (stEntity != null) {
            stEntity.setFirstName(std.getFirstName());
            stEntity.setLastName(std.getLastName());
            stEntity.setGrade(std.getGrade());
            studentDao.updateStudent(stEntity);

        }

    }

    public void delete(Long id) {
        Student stEntity = studentDao.getStudent(id);
        if (stEntity != null) {
            studentDao.deleteStudent(stEntity);
        }

    }

    public boolean isStudentUnique(Long id) {
        Student student = studentDao.getStudent(id);
        return (student == null || (id != null & !id.equals(student.getId())));
    }

}

抽象道 AbstractDaoClass

package com.springmvc.student.configuration.DAO;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;

public class AbstractDao <PK extends Serializable, T>{

    @Autowired
    private SessionFactory sessionFactory;
    
    @SuppressWarnings("rawtypes")
    private final Class persistentClass;
    
    @SuppressWarnings("rawtypes")
    public AbstractDao() {
        this.persistentClass = (Class) ((ParameterizedType) this.getClass().getGenericSuperclass()).getActualTypeArguments()[1];
    }
    
    protected Session getSession() {
        return sessionFactory.getCurrentSession();
    }
    
    @SuppressWarnings("unchecked")
    public T getByKey(PK key) {
        return (T) getSession().get(persistentClass, key);
    }
    
    public void persist(T entity) {
        getSession().persist(entity);
    }
    
    public void update(T entity) {
        getSession().update(entity);
    }
    
    public void delete(T entity) {
        getSession().delete(entity);
    }
    
    protected Criteria createEntityCriteria() {
        return getSession().createCriteria(persistentClass);
    }
    
    
}

我第一次使用抽象道，请告诉我我做错了什么！

DaoImplementationClass

package com.springmvc.student.configuration.DAO;

import java.util.List;

import org.hibernate.Criteria;

import com.springmvc.student.configuration.model.Student;

public class StudentDaoImpl extends AbstractDao<Long, Student> implements StudentDao {

    public Student getStudent(Long id) {

        return getByKey(id);
    }

    public Long saveStudent(Student std) {
        persist(std);
        return std.getId();
    }

    @SuppressWarnings({ "unchecked", "rawtypes" })
    public List<Student> listAllStudent() {
        Criteria criteria = createEntityCriteria();
        return (List) criteria.list();
    }

    public void updateStudent(Student std) {
        update(std);

    }

    public void deleteStudent(Student std) {
        delete(std);

    }

}

Answer 1

你需要添加@Service

package com.springmvc.student.configuration.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;

import com.springmvc.student.configuration.DAO.StudentDao;
import com.springmvc.student.configuration.model.Student;

    @Service //Tell Spring to put an instance of this class in spring context
    public class StudentServiceImpl implements StudentService {
    
        @Autowired
        private StudentDao studentDao;
    
     //A lot of code removed for brevity
    
    }

可以使用不同类型的刻板印象：

Spring 框架原型注解

@Component

此注解用于类上以指示 Spring 组件。这 @Component 注解将 Java 类标记为 bean 或说组件 以便 Spring 的组件扫描机制可以添加到 应用程序上下文。

@Controller

@Controller 注解用于表明该类是一个 Spring 控制器。此注解可用于识别控制器 Spring MVC 或 Spring WebFlux。

@Service

这个注解用于一个类。 @Service 标记一个 Java 类 执行某些服务，例如执行业务逻辑，执行 计算和调用外部 API。这个注解是专门的 打算在服务中使用的@Component 注释的形式 层。

@Repository

此注解用于直接访问 数据库。 @Repository 注释可用作任何类的标记 完成存储库或数据访问对象的角色。

此注释具有自动翻译功能。例如，当 @Repository 中发生异常有一个处理程序 异常，无需添加try catch块。

https://springframework.guru/spring-framework-annotations/

消息"No qualifying bean of type 'com.springmvc.student.configuration.service.StudentService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}"表示spring上下文中没有StudentService类型的bean。因此，您需要将 @Service 添加到类中，或者以与在 MyAppConfig 中使用其他两个 bean 相同的方式手动创建 bean。