Spring Boot+Hibernate接口请求异常：/rest/test无法返回预期内容

我的StudentController类上配置了@RequestMapping("/rest")，test方法配置了@GetMapping("/test")，按配置访问http://localhost:8080/TestHibernate/rest/test应返回字符串'Success'，但实际未得到预期结果。访问http://localhost:8080/TestHibernate可正常获取index文件内容。

提供的代码与配置 #

Controller层 #

package com.akshay.controller;

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.akshay.dao.StudentDAO;
import com.akshay.entity.Student;

@RestController
@RequestMapping("/rest")
public class StudentController {

    @Autowired
    private StudentDAO studentDAO;

    @PostMapping("/saveStudent")
    public String save(@RequestBody Student student) {
        studentDAO.saveStudent(student);
        return "Saved Successfully";
    }
    
    @GetMapping("/test")
    public String test() {
        return "Success";
    }
}

DAO层 #

package com.akshay.dao;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import com.akshay.entity.Student;

@Repository
@Transactional
public class StudentDAO {

    @Autowired
    private SessionFactory factory;
    
    private Session getSession() {
        Session session = factory.getCurrentSession();
        if(session == null) {
            session = factory.openSession();
        }
        return session;
    }
    
    public void saveStudent(Student student) {
        getSession().save(student);
    }
}

Entity层 #

package com.akshay.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 = "student")
public class Student {

    @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 Student() {

    }

    public Student(String firstName, String lastName, String email) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
    }

    public int getId() {
        return id;
    }

    public void setId(int 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 "Student [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
    }
}

启动类 #

package com.akshay.TestHibernate;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class TestHibernateApplication {

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

}

POM文件 #

<?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>2.5.0</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.akshay</groupId>
    <artifactId>TestHibernate</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>TestHibernate</name>
    <description>Demo project to test hibernate and mysql</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <!--<scope>provided</scope> -->
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

</project>

application.properties配置 #

#
# JDBC connection properties
#
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/web_student_tracker
jdbc.user=springstudent
jdbc.password=springstudent

#
# 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.akshay.entity

核心问题及解决方法 #

1. Spring Boot自动扫描范围不包含Controller包 #

启动类TestHibernateApplication在com.akshay.TestHibernate包下，@SpringBootApplication默认只扫描启动类所在包及其子包，导致com.akshay.controller下的Controller无法被Spring容器识别。

解决方法：

• 方案一：将启动类移动到com.akshay包下，自动扫描所有子包
• 方案二：在启动类注解中指定扫描范围：

@SpringBootApplication(scanBasePackages = "com.akshay")

2. 数据库配置不符合Spring Boot规范 #

当前使用的是传统Hibernate配置项，Spring Boot无法自动加载这些配置，会导致数据库连接、SessionFactory初始化失败，进而影响Controller的正常加载。

解决方法：
替换为Spring Boot标准JPA配置：

# 数据库连接配置
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/web_student_tracker?useSSL=false&serverTimezone=UTC
spring.datasource.username=springstudent
spring.datasource.password=springstudent

# JPA/Hibernate配置
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect

注：MySQL 8.x及以上版本建议使用com.mysql.cj.jdbc.Driver驱动，同时指定时区参数

3. DAO层SessionFactory注入问题 #

Spring Boot中推荐使用EntityManager而非直接注入SessionFactory，未配置的情况下SessionFactory会注入失败，导致容器启动异常。

解决方法：
改用EntityManager实现DAO逻辑：

@Repository
@Transactional
public class StudentDAO {

    @PersistenceContext
    private EntityManager entityManager;
    
    public void saveStudent(Student student) {
        entityManager.persist(student);
    }
}

4. 项目上下文路径验证 #

访问URL中的TestHibernate是上下文路径，需确认Spring Boot是否配置了该路径：

• 查看启动日志，若没有Tomcat started on port(s): 8080 (http) with context path '/TestHibernate'的日志，说明上下文路径为空，应访问http://localhost:8080/rest/test
• 若需要指定上下文路径，在application.properties中添加：

server.servlet.context-path=/TestHibernate

内容的提问来源于stack exchange，提问作者Akshay