Question

我是Hibernate和springboot的新手。我希望有人告诉我何时以及为什么要使用EntityManager或SessionFactory？另外，请简要介绍一下对于dB和其他配置，我们应该使用基于Java的配置还是基于XML的配置。

上述查询与我正在从事的项目有关：

项目：

我有一个使用Springboot和hibernate的简单的基于REST的API项目，在这里我需要使用GET和POST请求构建注册和登录机制。每当我尝试发出POST请求以创建资源时（在这种情况下，请创建一个新用户），我都会在POSTMAN和Eclipse IDE上收到以下错误消息：

我使用POSTMAN进行的POST请求

{
    "userId": "12345",
    "pin": "1234"
}

发出POST请求时，POSTMAN出错

    {
    "timestamp": 1551809931747,
    "status": 500,
    "error": "Internal Server Error",
    "exception": "java.lang.ClassCastException",
    "message": "org.springframework.orm.jpa.EntityManagerHolder cannot be cast to org.springframework.orm.hibernate4.SessionHolder",
    "path": "/employee/register"
}

错误的完整堆栈跟踪

java.lang.ClassCastException: org.springframework.orm.jpa.EntityManagerHolder cannot be cast to org.springframework.orm.hibernate4.SessionHolder
    at org.springframework.orm.hibernate4.HibernateTransactionManager.doGetTransaction(HibernateTransactionManager.java:380) ~[spring-orm-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:341) ~[spring-tx-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:461) ~[spring-tx-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:277) ~[spring-tx-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) ~[spring-tx-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:671) ~[spring-aop-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at com.cerner.project.dao.EmployeeDAO$$EnhancerBySpringCGLIB$$1b4cb760.registerUser(<generated>) ~[classes/:na]
    at com.cerner.project.controller.EmployeeController.registerUser(EmployeeController.java:28) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_201]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_201]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_201]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:849) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:760) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55) ~[spring-boot-1.5.19.RELEASE.jar:1.5.19.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:111) ~[spring-boot-actuator-1.5.19.RELEASE.jar:1.5.19.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) ~[spring-boot-actuator-1.5.19.RELEASE.jar:1.5.19.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.22.RELEASE.jar:4.3.22.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:1.8.0_201]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:1.8.0_201]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.37.jar:8.5.37]
    at java.lang.Thread.run(Unknown Source) [na:1.8.0_201]

什么是导致此错误的问题？我只想做一个简单的POST。

以下是我的文件： User.Java

    package com.cerner.project.model;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="user")
public class User {

    @Id
    @Column(name="user_id")
    private int userId;

    @Column(name="pin")
    //@ColumnTransformer(read = "sha1(pin)",write = "sha1(?)")
    private String pin;

    @OneToMany(cascade=CascadeType.ALL)
    @JoinColumn(name="user_id")
    private List<UserLog> userLog=new ArrayList<UserLog>();

    public List<UserLog> getUserLog() {
        return userLog;
    }

    public void setUserLog(List<UserLog> userLog) {
        this.userLog = userLog;
    }

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }

    public String getPin() {
        return pin;
    }

    public void setPin(String pin) {
        this.pin = pin;
    }

    public User() {

    }
    public User(int userId, String pin) {
        this.userId = userId;
        this.pin= pin;
    }
    //CLOVER:OFF
    @Override
    public String toString() {
        return "User [userId=" + userId + ", pin=" + pin + "]";
    }
    //CLOVER:ON
}

EmployeeDao.Java

        package com.cerner.project.dao;

    import java.util.ArrayList;
    import java.util.List;

    import javax.transaction.Transactional;

    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.cfg.Configuration;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Repository;
    import org.springframework.stereotype.Service;

    import com.cerner.project.model.Team;
    import com.cerner.project.model.User;
    import com.cerner.project.model.UserLog;

    //@Service
    @Repository
    @Transactional
    public class EmployeeDAO {

        @Autowired
        private SessionFactory sessionFactory;

        private Session getSession() {
            return sessionFactory.getCurrentSession();
        }

        public User registerUser(User user) {
            int userId=user.getUserId();
            user.setUserId(userId);
            String userPin=user.getPin();
            user.setPin(userPin);
            return user;
        }

        public List<User> getAllUsers() {
            List<User> users=new ArrayList<User>();
              User user1=new User(11111,"1234");
            User user2=new User(22222,"4321");
            users.add(user1);
            users.add(user2);
            getSession().beginTransaction();
            getSession().save(user1);
            getSession().save(user1);
            getSession().getTransaction().commit();
            return users;
        }
    }

EmployeeController.Java

    package com.cerner.project.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.cerner.project.dao.EmployeeDAO;
import com.cerner.project.model.User;

@RestController
@RequestMapping("/employee")
public class EmployeeController {

    @Autowired
    private EmployeeDAO employeeDao;

    @RequestMapping("/test")
    public String test() {
        return "Hello World!";
    }
    @PostMapping("/register")
    public String registerUser(@RequestBody User user) {
        employeeDao.registerUser(user);
        return("SUCCESS");
    }


    @GetMapping("/getUsers")
    public List<User> getAllUsers(){
        return employeeDao.getAllUsers();

    }

}

DBConfiguration.Java

    package com.cerner.project.config;

import java.util.Properties;

import javax.sql.DataSource;

import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate4.HibernateTransactionManager;
import org.springframework.orm.hibernate4.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@PropertySource(value = { "classpath:application.properties" })
@Configuration
//@EnableTransactionManagement
public class DBConfiguration {

    @Value("${jdbc.driverClassName}")
    private String driverClass;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String username;
    @Value("${jdbc.password}")
    private String password;
    @Value("${hibernate.dialect}")
    private String dialect;

    @Bean
    public DataSource getDataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource(url, username, password);
        dataSource.setDriverClassName(driverClass);
        return dataSource;
    }

    @Bean
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean factory = new LocalSessionFactoryBean();
        factory.setDataSource(getDataSource());
        factory.setHibernateProperties(hibernateProperties());
        factory.setPackagesToScan(new String[] { "com.cerner.project" });
        return factory;
    }

    private Properties hibernateProperties() {
        Properties properties = new Properties();
        properties.put("hibernate.dialect", dialect);
        properties.put("hibernate.hbm2ddl.auto", "update");
        properties.put("hibernate.show_sql", "true");
        properties.put("hibernate.format_sql", "true");
        return properties;
    }

    @Bean
    @Autowired
    public HibernateTransactionManager transactionManager(SessionFactory factory) {
        HibernateTransactionManager transactionManager = new HibernateTransactionManager();
        transactionManager.setSessionFactory(factory);
        return transactionManager;
    }
}

Answer 1

EntityManager是JPA（Java持久性API）的一部分，JPA是用于对象关系映射的标准Java EE API。 Hibernate是JPA的可用实现之一，SessionFactory是Hibernate的一部分。

这意味着，如果直接使用SessionFactory，则使用的是Hibernate特定的功能，而当您使用EntityManager时，则使用的是JPA，而您并没有将代码绑定到一个特定的JPA实现，例如Hibernate。

因此，最好使用EntityManager，这样（原则上）以后可以将Hibernate换成其他JPA实现。因此，例如，除非有充分的理由，否则您需要使用JPA无法使用的特定于Hibernate的功能，请使用EntityManager而不是SessionFactory。

如果您使用EntityManager，但仍需要特定于Hibernate的Session，因为您需要执行特定于Hibernate的操作，则可以使用EntityManager.unwrap(Session.class)：

Session session = EntityManager.unwrap(Session.class);

但是，更好的选择是使用Spring Data JPA，这使使用数据库更加容易-您不必实现DAO，只需声明存储库接口即可。使用Spring Data JPA时，您不必直接使用EntityManger或SessionFactory。

我们应该在Hibernate和Springboot中使用什么。 SesssionFactory或EntityManager

1 个答案: