小贝子编程

春季休眠，GET查询，休眠查询成功形成，我能够从数据库获取数据，但是当我从浏览器点击时，它抛出404



我目前正在使用Hibernate学习Spring。。我有一个简单的Customer表，其中的列是"ID"、"first_name"、"last_name"one_answers"email"。。

我使用hibernate来查询数据库，并将所有客户的结果作为输出列出。。我已经将Spring引导与MVC一起用于相同的目的。。

问题是我能够成功地从数据库中提取数据，并且能够在控制台中打印。。但当我试图通过浏览器通过GET请求访问它时，它会抛出404错误。。

我的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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>hibernate.mapping.onetoone</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>hibernate.mapping.onetoone</name>
<description>Demo project for Hibernate One to One</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.4.10.Final</version>
</dependency>
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
</dependency>
<!-- https://mvnrepository.com/artifact/jstl/jstl -->
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
<scope>provided</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework/spring-orm -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>5.2.2.RELEASE</version>
</dependency>
<!-- https://mvnrepository.com/artifact/c3p0/c3p0 -->
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web-services</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
enter code here
enter code here

和我的SpringMain应用程序类

package com.example.hibernate.crud;
import java.beans.PropertyVetoException;
import java.util.Properties;
import javax.sql.DataSource;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import com.mchange.v2.c3p0.ComboPooledDataSource;
@SpringBootApplication
@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class, HibernateJpaAutoConfiguration.class})
@ComponentScan("com.example.hibernate.crud.*")
@EntityScan("com.example.hibernate.crud.*")
@EnableTransactionManagement
@PropertySource({"classpath:persistence-mysql.properties"})
public class HibernateApplication implements WebMvcConfigurer {
@Autowired
private Environment env;
public static void main(String[] args) {
SpringApplication.run(HibernateApplication.class, args);

}

@Bean
public DataSource myDataSource() {
// create connection pool
ComboPooledDataSource myDataSource = new ComboPooledDataSource();
// set the jdbc driver
try {
myDataSource.setDriverClass("com.mysql.cj.jdbc.Driver");
}
catch (PropertyVetoException exc) {
throw new RuntimeException(exc);
}
// set database connection props
myDataSource.setJdbcUrl(env.getProperty("jdbc.url"));
myDataSource.setUser(env.getProperty("jdbc.user"));
myDataSource.setPassword(env.getProperty("jdbc.password"));
// set connection pool props
myDataSource.setInitialPoolSize(Integer.parseInt(env.getProperty("connection.pool.initialPoolSize")));
myDataSource.setMinPoolSize(Integer.parseInt(env.getProperty("connection.pool.minPoolSize")));
myDataSource.setMaxPoolSize(Integer.parseInt(env.getProperty("connection.pool.maxPoolSize")));
myDataSource.setMaxIdleTime(Integer.parseInt(env.getProperty("connection.pool.maxIdleTime")));
return myDataSource;
}
private Properties getHibernateProperties() {
Properties props = new Properties();
props.setProperty("hibernate.dialect", env.getProperty("hibernate.dialect"));
props.setProperty("hibernate.show_sql", env.getProperty("hibernate.show_sql"));
return props;
} 
@Bean
public LocalSessionFactoryBean sessionFactory(){
// create session factorys
LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
// set the properties
sessionFactory.setDataSource(myDataSource());
sessionFactory.setPackagesToScan(env.getProperty("hibernate.packagesToScan"));
sessionFactory.setHibernateProperties(getHibernateProperties());
return sessionFactory;
}
@Bean
@Autowired
public HibernateTransactionManager transactionManager(SessionFactory sessionFactory) {
// setup transaction manager based on session factory
HibernateTransactionManager txManager = new HibernateTransactionManager();
txManager.setSessionFactory(sessionFactory);
return txManager;
}
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry
.addResourceHandler("/resources/**")
.addResourceLocations("WEB-INF/resources/");
}
}

和我的控制器类

package com.example.hibernate.crud.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import com.example.hibernate.crud.DAO.CustomerDAO;
import com.example.hibernate.crud.entity.Customer;
@Controller
@RequestMapping("/student")
public class StudentController {
@Autowired CustomerDAO customerDAO;
@GetMapping("/list")
public List<Customer> getStudentList() {
return customerDAO.getAllCustomers();
}
}

和我的实体类

package com.example.hibernate.crud.entity;
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="customer")
public class Customer {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id")
private int id;
@Column(name="first_name")
private String firstName;
@Column(name="last_name")
private String lastName;
@Column(name="email")
private String email;
public Customer() {
}
public Customer(String firstName, String lastName, String email) {
this.firstName = firstName;
this.lastName = lastName;
this.email = email;
}
@Override
public String toString() {
return "Customer [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
}

}

和我的DAO接口：

package com.example.hibernate.crud.DAO;
import java.util.List;
import com.example.hibernate.crud.entity.Customer;
public interface CustomerDAO {
public List<Customer> getAllCustomers();
}

我的DAO实现类：

package com.example.hibernate.crud.DAO;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
import com.example.hibernate.crud.entity.Customer;
@Repository
public class CustomerDAOImpl implements CustomerDAO {
@Autowired SessionFactory sessionfactory;
@Override
@Transactional
public List<Customer> getAllCustomers() {
Session session = sessionfactory.getCurrentSession();

System.out.println("REACHED UNTIL THIS..,");
Query<Customer> query = session.createQuery("from Customer", Customer.class);
//session.getTransaction().commit();
for(Customer c : query.getResultList()) {
System.out.println("REACHED LOOP");
System.out.println(c);
}
return query.getResultList();
}
}

我的属性文件：

#
# JDBC connection properties
#
jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false&serverTimezone=UTC
jdbc.user=root
jdbc.password=
#
# Connection pool properties
#
connection.pool.initialPoolSize=5
connection.pool.minPoolSize=5
connection.pool.maxPoolSize=20
connection.pool.maxIdleTime=3000
#
# Hibernate properties
#
hibernate.dialect=org.hibernate.dialect.MySQLDialect
hibernate.show_sql=true
hibernate.packagesToScan=com.example.hibernate.crud.entity

当我运行我的应用程序并点击以下URL时"http://localhost:8080/student/list"在浏览器中，我得到以下登录控制台：

控制台输出图像

从日志中可以看到，数据是从数据库中提取并打印在控制台中的。。但在浏览器中返回404，如下所示

浏览器输出图像

无法理解为什么会发生这种情况。。请澄清

附加DB模型以供参考：DB模型图像

从这个角度来看，问题很可能是您的控制器。您已经用@controller而不是@RestController注释了控制器。看看这篇文章；

@Controller的工作是创建模型对象的Map并查找视图，但@RestController只是返回对象和对象数据以JSON或XML的形式直接写入HTTP响应。

因此，基本上您可以执行以下两项操作：1.将@ResponseBody注释添加到您的getStudentList方法中；2.用@RestController 注释控制器类

希望这能有所帮助。

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