Java Spring@Transactional注释不工作

目前我正在做一个关于Udemy的春季课程，我对

CustomerDAO

类中的

@Transactional

注释有问题。我正在使用Maven和Java8。它根本不起作用，下面是Tomcat 9的响应：

HTTP Status 500 – Internal Server Error

Type Exception Report

Message Request processing failed; nested exception is javax.persistence.TransactionRequiredException: no transaction is in progress

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is javax.persistence.TransactionRequiredException: no transaction is in progress
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1013)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Root Cause

javax.persistence.TransactionRequiredException: no transaction is in progress
    org.hibernate.internal.SessionImpl.checkTransactionNeeded(SessionImpl.java:3552)
    org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1444)
    org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1440)
    org.springframework.orm.hibernate5.SessionFactoryUtils.flush(SessionFactoryUtils.java:147)
    org.springframework.orm.hibernate5.SpringSessionSynchronization.beforeCommit(SpringSessionSynchronization.java:95)
    org.springframework.transaction.support.TransactionSynchronizationUtils.triggerBeforeCommit(TransactionSynchronizationUtils.java:96)
    org.springframework.transaction.support.AbstractPlatformTransactionManager.triggerBeforeCommit(AbstractPlatformTransactionManager.java:922)
    org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:730)
    org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:714)
    org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:533)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:304)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
    net.matbm.springlearn.dao.CustomerDAO$$EnhancerBySpringCGLIB$$6447db19.getCustomers(<generated>)
    net.matbm.springlearn.dao.CustomerDAO$HOTSWAPAGENT_$$FastClassBySpringCGLIB$$466694ed.invoke(<generated>)
    org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
    HotswapSpringCallback_1796692748.intercept(HotswapSpringCallback_1796692748.java)
    net.matbm.springlearn.dao.CustomerDAO$HOTSWAPAGENT_$$EnhancerBySpringCGLIB$$feb7e678.getCustomers(<generated>)
    net.matbm.springlearn.service.CustomerService.getAllCustomers(CustomerService.java:16)
    net.matbm.springlearn.controller.CustomerController.listCustomers(CustomerController.java:26)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Note The full stack trace of the root cause is available in the server logs.

spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         id="WebApp_ID" version="3.1">

    <display-name>spring-mvc-demo</display-name>

    <!-- Spring MVC Configs -->

    <!-- Step 1: Configure Spring MVC Dispatcher Servlet -->
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- Step 2: Set up URL mapping for Spring MVC Dispatcher Servlet -->
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

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

    <!-- Add support for component scanning -->
    <context:component-scan base-package="net.matbm.springlearn.config"/>

    <mvc:default-servlet-handler/>
    <mvc:annotation-driven/>
</beans>

<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>net.matbm</groupId>
    <artifactId>SpringLearn</artifactId>
    <packaging>war</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>Spring Learn</name>
    <url>http://maven.apache.org</url>

    <properties>
        <spring.version>5.1.3.RELEASE</spring.version>
        <jdk.version>1.8</jdk.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-orm -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/javax.servlet/servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>3.0-alpha-1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.postgresql/postgresql -->
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.2.5</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.hibernate.validator/hibernate-validator -->
        <dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>6.0.13.Final</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.3.7.Final</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-c3p0 -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-c3p0</artifactId>
            <version>5.3.7.Final</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>SpringMaven</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <url>http://localhost:8080/manager/text</url>
                    <server>TomcatServer</server>
                    <path>/</path>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <source>${jdk.version}</source>
                    <target>${jdk.version}</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

net.matbm.controller.CustomerController.java

package net.matbm.springlearn.config;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.mchange.v2.c3p0.PooledDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

import java.beans.PropertyVetoException;
import java.util.Properties;

@Configuration
@EnableWebMvc
@EnableTransactionManagement
@ComponentScan("net.matbm.springlearn")
public class AppConfig implements WebMvcConfigurer {
    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");

        return resolver;
    }

    @Bean(destroyMethod = "close")
    public PooledDataSource dataSource() throws PropertyVetoException {
        ComboPooledDataSource source = new ComboPooledDataSource();

        source.setDriverClass("org.postgresql.Driver");
        source.setJdbcUrl("jdbc:postgresql://localhost/java");

        source.setUser("java");
        source.setPassword("java");

        source.setMinPoolSize(5);
        source.setMinPoolSize(20);
        source.setMinPoolSize(3000);

        return source;
    }

    @Bean
    public LocalSessionFactoryBean sessionFactory() throws PropertyVetoException {
        LocalSessionFactoryBean factoryBean = new LocalSessionFactoryBean();

        factoryBean.setDataSource(dataSource());
        factoryBean.setPackagesToScan("net.matbm.springlearn.model");

        factoryBean.setHibernateProperties(hibernateProperties());

        return factoryBean;
    }

    @Bean
    public PlatformTransactionManager transactionManager() throws PropertyVetoException {
        HibernateTransactionManager manager = new HibernateTransactionManager();
        manager.setSessionFactory(sessionFactory().getObject());

        return manager;
    }

    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("resources/");
    }

    private Properties hibernateProperties() {
        Properties hibernateProperties = new Properties();

        hibernateProperties.setProperty("hibernate.dialect", "org.hibernate.dialect.PostgreSQL95Dialect");
        hibernateProperties.setProperty("hibernate.show_sql", "true");
        hibernateProperties.setProperty("hibernate.hbm2ddl.auto", "create");

        return hibernateProperties;

    }
}

package net.matbm.springlearn.controller;

import net.matbm.springlearn.service.CustomerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/customer")
public class CustomerController {
    private final CustomerService customerService;

    @Autowired
    public CustomerController(CustomerService customerService) {
        this.customerService = customerService;
    }

    @RequestMapping()
    public String home() {
        return "customer/home";
    }

    @RequestMapping("/list")
    public String listCustomers(Model model) {
        model.addAttribute("customers", customerService.getAllCustomers());

        return "customer/list-customers";
    }
}

package net.matbm.springlearn.service;

import net.matbm.springlearn.dao.CustomerDAO;
import net.matbm.springlearn.model.Customer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class CustomerService {
    @Autowired
    private CustomerDAO customerDAO;

    public List<Customer> getAllCustomers() {
        return customerDAO.getCustomers();
    }
}

package net.matbm.springlearn.dao;

import net.matbm.springlearn.model.Customer;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Repository
public class CustomerDAO {
    @Autowired
    private SessionFactory sessionFactory;

    @Transactional
    public List<Customer> getCustomers() {
        Session session = sessionFactory.getCurrentSession();

        Query<Customer> query =
                session.createQuery("from Customer", Customer.class);

        return query.getResultList();
    }
}

package net.matbm.springlearn.model;

import javax.persistence.*;

@Entity
@Table(name = "customer")
public class Customer {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    @Column(name = "email")
    private String email;

    public Customer() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", firstName='" + firstName + '\'' +
                ", lastName='" + lastName + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

net.matbm.service.CustomerService.java

package net.matbm.springlearn.config;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.mchange.v2.c3p0.PooledDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

import java.beans.PropertyVetoException;
import java.util.Properties;

@Configuration
@EnableWebMvc
@EnableTransactionManagement
@ComponentScan("net.matbm.springlearn")
public class AppConfig implements WebMvcConfigurer {
    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");

        return resolver;
    }

    @Bean(destroyMethod = "close")
    public PooledDataSource dataSource() throws PropertyVetoException {
        ComboPooledDataSource source = new ComboPooledDataSource();

        source.setDriverClass("org.postgresql.Driver");
        source.setJdbcUrl("jdbc:postgresql://localhost/java");

        source.setUser("java");
        source.setPassword("java");

        source.setMinPoolSize(5);
        source.setMinPoolSize(20);
        source.setMinPoolSize(3000);

        return source;
    }

    @Bean
    public LocalSessionFactoryBean sessionFactory() throws PropertyVetoException {
        LocalSessionFactoryBean factoryBean = new LocalSessionFactoryBean();

        factoryBean.setDataSource(dataSource());
        factoryBean.setPackagesToScan("net.matbm.springlearn.model");

        factoryBean.setHibernateProperties(hibernateProperties());

        return factoryBean;
    }

    @Bean
    public PlatformTransactionManager transactionManager() throws PropertyVetoException {
        HibernateTransactionManager manager = new HibernateTransactionManager();
        manager.setSessionFactory(sessionFactory().getObject());

        return manager;
    }

    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("resources/");
    }

    private Properties hibernateProperties() {
        Properties hibernateProperties = new Properties();

        hibernateProperties.setProperty("hibernate.dialect", "org.hibernate.dialect.PostgreSQL95Dialect");
        hibernateProperties.setProperty("hibernate.show_sql", "true");
        hibernateProperties.setProperty("hibernate.hbm2ddl.auto", "create");

        return hibernateProperties;

    }
}

package net.matbm.springlearn.controller;

import net.matbm.springlearn.service.CustomerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/customer")
public class CustomerController {
    private final CustomerService customerService;

    @Autowired
    public CustomerController(CustomerService customerService) {
        this.customerService = customerService;
    }

    @RequestMapping()
    public String home() {
        return "customer/home";
    }

    @RequestMapping("/list")
    public String listCustomers(Model model) {
        model.addAttribute("customers", customerService.getAllCustomers());

        return "customer/list-customers";
    }
}

package net.matbm.springlearn.service;

import net.matbm.springlearn.dao.CustomerDAO;
import net.matbm.springlearn.model.Customer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class CustomerService {
    @Autowired
    private CustomerDAO customerDAO;

    public List<Customer> getAllCustomers() {
        return customerDAO.getCustomers();
    }
}

package net.matbm.springlearn.dao;

import net.matbm.springlearn.model.Customer;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Repository
public class CustomerDAO {
    @Autowired
    private SessionFactory sessionFactory;

    @Transactional
    public List<Customer> getCustomers() {
        Session session = sessionFactory.getCurrentSession();

        Query<Customer> query =
                session.createQuery("from Customer", Customer.class);

        return query.getResultList();
    }
}

package net.matbm.springlearn.model;

import javax.persistence.*;

@Entity
@Table(name = "customer")
public class Customer {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    @Column(name = "email")
    private String email;

    public Customer() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", firstName='" + firstName + '\'' +
                ", lastName='" + lastName + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

net.matbm.model.Customer.java

package net.matbm.springlearn.config;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.mchange.v2.c3p0.PooledDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

import java.beans.PropertyVetoException;
import java.util.Properties;

@Configuration
@EnableWebMvc
@EnableTransactionManagement
@ComponentScan("net.matbm.springlearn")
public class AppConfig implements WebMvcConfigurer {
    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");

        return resolver;
    }

    @Bean(destroyMethod = "close")
    public PooledDataSource dataSource() throws PropertyVetoException {
        ComboPooledDataSource source = new ComboPooledDataSource();

        source.setDriverClass("org.postgresql.Driver");
        source.setJdbcUrl("jdbc:postgresql://localhost/java");

        source.setUser("java");
        source.setPassword("java");

        source.setMinPoolSize(5);
        source.setMinPoolSize(20);
        source.setMinPoolSize(3000);

        return source;
    }

    @Bean
    public LocalSessionFactoryBean sessionFactory() throws PropertyVetoException {
        LocalSessionFactoryBean factoryBean = new LocalSessionFactoryBean();

        factoryBean.setDataSource(dataSource());
        factoryBean.setPackagesToScan("net.matbm.springlearn.model");

        factoryBean.setHibernateProperties(hibernateProperties());

        return factoryBean;
    }

    @Bean
    public PlatformTransactionManager transactionManager() throws PropertyVetoException {
        HibernateTransactionManager manager = new HibernateTransactionManager();
        manager.setSessionFactory(sessionFactory().getObject());

        return manager;
    }

    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("resources/");
    }

    private Properties hibernateProperties() {
        Properties hibernateProperties = new Properties();

        hibernateProperties.setProperty("hibernate.dialect", "org.hibernate.dialect.PostgreSQL95Dialect");
        hibernateProperties.setProperty("hibernate.show_sql", "true");
        hibernateProperties.setProperty("hibernate.hbm2ddl.auto", "create");

        return hibernateProperties;

    }
}

package net.matbm.springlearn.controller;

import net.matbm.springlearn.service.CustomerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/customer")
public class CustomerController {
    private final CustomerService customerService;

    @Autowired
    public CustomerController(CustomerService customerService) {
        this.customerService = customerService;
    }

    @RequestMapping()
    public String home() {
        return "customer/home";
    }

    @RequestMapping("/list")
    public String listCustomers(Model model) {
        model.addAttribute("customers", customerService.getAllCustomers());

        return "customer/list-customers";
    }
}

package net.matbm.springlearn.service;

import net.matbm.springlearn.dao.CustomerDAO;
import net.matbm.springlearn.model.Customer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class CustomerService {
    @Autowired
    private CustomerDAO customerDAO;

    public List<Customer> getAllCustomers() {
        return customerDAO.getCustomers();
    }
}

package net.matbm.springlearn.dao;

import net.matbm.springlearn.model.Customer;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Repository
public class CustomerDAO {
    @Autowired
    private SessionFactory sessionFactory;

    @Transactional
    public List<Customer> getCustomers() {
        Session session = sessionFactory.getCurrentSession();

        Query<Customer> query =
                session.createQuery("from Customer", Customer.class);

        return query.getResultList();
    }
}

package net.matbm.springlearn.model;

import javax.persistence.*;

@Entity
@Table(name = "customer")
public class Customer {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    @Column(name = "email")
    private String email;

    public Customer() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", firstName='" + firstName + '\'' +
                ", lastName='" + lastName + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         id="WebApp_ID" version="3.1">

    <display-name>spring-mvc-demo</display-name>

    <!-- Spring MVC Configs -->

    <!-- Step 1: Configure Spring MVC Dispatcher Servlet -->
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- Step 2: Set up URL mapping for Spring MVC Dispatcher Servlet -->
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

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

    <!-- Add support for component scanning -->
    <context:component-scan base-package="net.matbm.springlearn.config"/>

    <mvc:default-servlet-handler/>
    <mvc:annotation-driven/>
</beans>

<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>net.matbm</groupId>
    <artifactId>SpringLearn</artifactId>
    <packaging>war</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>Spring Learn</name>
    <url>http://maven.apache.org</url>

    <properties>
        <spring.version>5.1.3.RELEASE</spring.version>
        <jdk.version>1.8</jdk.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-orm -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/javax.servlet/servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>3.0-alpha-1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.postgresql/postgresql -->
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.2.5</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.hibernate.validator/hibernate-validator -->
        <dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>6.0.13.Final</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.3.7.Final</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-c3p0 -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-c3p0</artifactId>
            <version>5.3.7.Final</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>SpringMaven</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <url>http://localhost:8080/manager/text</url>
                    <server>TomcatServer</server>
                    <path>/</path>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <source>${jdk.version}</source>
                    <target>${jdk.version}</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

4.0.0
net.matbm
春季学习
战争
1.0-快照
春季学习
http://maven.apache.org
5.1.3.1发布
1.8
org.springframework
弹簧芯
${spring.version}
org.springframework
弹簧网
${spring.version}
org.springframework
SpringWebMVC
${spring.version}
org.springframework
SpringJDBC
${spring.version}
org.springframework
春季甲虫
${spring.version}
javax.servlet
servlet api
3.0-α-1
假如
朱尼特
朱尼特
3.8.1
测试
org.postgresql
postgresql
42.2.5
org.hibernate.validator
休眠验证器
6.0.13.1最终版本
org.hibernate
冬眠核心
5.3.7.最终版本
org.hibernate
hibernate-c3p0
5.3.7.最终版本
斯普林马文
org.apache.tomcat.maven
tomcat7 maven插件
2.2
http://localhost:8080/manager/text
TomcatServer
/
org.apache.maven.plugins
maven编译器插件
3.8.0
${jdk.version}
${jdk.version}

---

提前感谢。

根据例外情况，您的transactionManager配置似乎不正确

使用

平台TransactionManager

的具体原因是什么

如果没有，请使用此配置

事务usinHibernatete 4的工作配置如下所示

@Configuration
@EnableTransactionManagement
@PropertySource({ "classpath:persistence-mysql.properties" })
@ComponentScan({ "org.baeldung.spring.persistence" })
public class PersistenceConfig {

   @Autowired
   private Environment env;

   @Bean
   public LocalSessionFactoryBean sessionFactory() {
      LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
      sessionFactory.setDataSource(restDataSource());
      sessionFactory.setPackagesToScan(
        new String[] { "org.baeldung.spring.persistence.model" });
      sessionFactory.setHibernateProperties(hibernateProperties());

      return sessionFactory;
   }

   @Bean
   public DataSource restDataSource() {
      BasicDataSource dataSource = new BasicDataSource();
      dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
      dataSource.setUrl(env.getProperty("jdbc.url"));
      dataSource.setUsername(env.getProperty("jdbc.user"));
      dataSource.setPassword(env.getProperty("jdbc.pass"));

      return dataSource;
   }

   @Bean
   @Autowired
   public HibernateTransactionManager transactionManager(
     SessionFactory sessionFactory) {

      HibernateTransactionManager txManager
       = new HibernateTransactionManager();
      txManager.setSessionFactory(sessionFactory);

      return txManager;
   }

   @Bean
   public PersistenceExceptionTranslationPostProcessor exceptionTranslation() {
      return new PersistenceExceptionTranslationPostProcessor();
   }

   Properties hibernateProperties() {
      return new Properties() {
         {
            setProperty("hibernate.hbm2ddl.auto",
              env.getProperty("hibernate.hbm2ddl.auto"));
            setProperty("hibernate.dialect",
              env.getProperty("hibernate.dialect"));
            setProperty("hibernate.globally_quoted_identifiers",
             "true");
         }
      };
   }
}

更多细节

Else如果您想要

PlatformTransactionManager的解决方案

---

更改

客户DAO

后，可能会有帮助，事务开始工作：

@Repository
public class CustomerDAOImpl implements CustomerDAO {
    @PersistenceContext
    private EntityManager entityManager;

    public List<Customer> getCustomers() {
        Query<Customer> query =
                (Query<Customer>) entityManager.createQuery("from Customer", Customer.class);

        return query.getResultList();
    }
}

@存储库
公共类CustomerDAOImpl实现CustomerDAO{
@持久上下文
私人实体管理者实体管理者；
公共列表getCustomers（）{
查询=
（Query）entityManager.createQuery（“来自客户”，Customer.class）；
返回query.getResultList（）；
}
}

---

使用

@PersistenceContext

而不是

会话工厂

解决了问题。我不知道为什么。

在服务层，您使用了@Autowired注释，在DAO层，您使用了@Tranjaction注释，因此它给出了一个错误

因此，在服务层中使用@Transactional注释，在DAO层中使用@Autowired注释

在如下所示的服务层中进行更改

 import net.matbm.springlearn.dao.CustomerDAO;
    import net.matbm.springlearn.model.Customer;
     import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;

     import java.util.List;

    @Service
    public class CustomerService {
        @Autowired
        private CustomerDAO customerDAO;
     @Transactional
        public List<Customer> getAllCustomers() {
            return customerDAO.getCustomers();
        }
    }

package net.matbm.springlearn.dao;
import net.matbm.springlearn.model.Customer;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Repository
public class CustomerDAO {
    @Autowired
    private SessionFactory sessionFactory;

   @Override
    public List<Customer> getCustomers() {
        Session session = sessionFactory.getCurrentSession();

        Query<Customer> query =
                session.createQuery("from Customer", Customer.class);

        return query.getResultList();
    }
}

import net.matbm.springlearn.dao.CustomerDAO；
导入net.matbm.springlearn.model.Customer；
导入org.springframework.beans.factory.annotation.Autowired；
导入org.springframework.stereotype.Service；
导入java.util.List；
@服务
公共类客户服务{
@自动连线
私人客户道客户道；
@交易的
公共列表getAllCustomers（）{
返回customerDAO.getCustomers（）；
}
}

在DAO层中进行更改，如下所示

 import net.matbm.springlearn.dao.CustomerDAO;
    import net.matbm.springlearn.model.Customer;
     import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;

     import java.util.List;

    @Service
    public class CustomerService {
        @Autowired
        private CustomerDAO customerDAO;
     @Transactional
        public List<Customer> getAllCustomers() {
            return customerDAO.getCustomers();
        }
    }

package net.matbm.springlearn.dao;
import net.matbm.springlearn.model.Customer;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Repository
public class CustomerDAO {
    @Autowired
    private SessionFactory sessionFactory;

   @Override
    public List<Customer> getCustomers() {
        Session session = sessionFactory.getCurrentSession();

        Query<Customer> query =
                session.createQuery("from Customer", Customer.class);

        return query.getResultList();
    }
}

package net.matbm.springlearn.dao；
导入net.matbm.springlearn.model.Customer；
导入org.hibernate.Session；
导入org.hibernate.SessionFactory；
导入org.hibernate.query.query；
导入org.springframework.beans.factory.annotation.Autowired；
导入org.springframework.stereotype.Repository；
导入org.springframework.transaction.annotation.Transactional；
导入java.util.List；
@存储库
公共类客户道{
@自动连线
私人会话工厂会话工厂；
@凌驾
公共列表getCustomers（）{
Session Session=sessionFactory.getCurrentSession（）；
查询=
createQuery（“来自客户”，Customer.class）；
返回query.getResultList（）；
}
}

我不知道您的问题，只需在服务层使用

@Transactional

。我也尝试过（我查看了文档，应该在服务层使用）。但这并没有解决问题。嗨，谢谢你的快速回复。我曾经设置过

平台TransactionManager

，这就是我使用它的原因。不幸的是，做出您建议的更改并没有解决问题。在创建此问题之前，我已经查看了您发布的第二个链接。我在这里发表了评论：这也是问题所在，官方文档指定

@Transactional

需要位于服务层。