JAVA SPRING - org.springframework.beans.factory.UnsatisfiedDependencyException：創建名為“employeeController”的 bean 時出錯：

Question

我是 Spring 的新手，正在嘗試使用 Hibernate 制作 Spring MVC 應用程序。 我在嘗試啟動應用程序時遇到問題

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'employeeController': Unsatisfied dependency expressed through field 'employeeService'; nested exception is org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.mchange.v2.c3p0.ComboPooledDataSource] for bean with name 'myDataSource' defined in ServletContext resource [/WEB-INF/spring-mvc-forms-servlet.xml]; nested exception is java.lang.ClassNotFoundException: com.mchange.v2.c3p0.ComboPooledDataSource

這是我的代碼

Employee.java（實體）

package com.john.springmvc.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="employee")
public class Employee {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id")
    private int id;
    
    @Column(name="employee_id")
    private int employeeId;
    
    @Column(name="first_name")
    private String firstName;
    
    @Column(name="last_name")
    private String lastName;
    
    @Column(name="contact_number")
    private String contactNumber;
    
    @Column(name="email_address")
    private String emailAddress;
    
    public Employee() {
        
    }
    
    public Employee(int employeeId, String firstName, String lastName, String contactNumber, String emailAddress) {
        this.employeeId = employeeId;
        this.firstName = firstName;
        this.lastName = lastName;
        this.contactNumber = contactNumber;
        this.emailAddress = emailAddress;
    }

    public int getId() {
        return id;
    }

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

    public int getEmployeeId() {
        return employeeId;
    }

    public void setEmployeeId(int employeeId) {
        this.employeeId = employeeId;
    }

    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 getContactNumber() {
        return contactNumber;
    }

    public void setContactNumber(String contactNumber) {
        this.contactNumber = contactNumber;
    }

    public String getEmailAddress() {
        return emailAddress;
    }

    public void setEmailAddress(String emailAddress) {
        this.emailAddress = emailAddress;
    }

    @Override
    public String toString() {
        return "Employee [id=" + id + ", employeeId=" + employeeId + ", firstName=" + firstName + ", lastName="
                + lastName + ", contactNumber=" + contactNumber + ", emailAddress=" + emailAddress + "]";
    }
    
}

雇員控制器.java

package com.john.springmvc.controller;

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.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import com.john.springmvc.entity.Employee;
import com.john.springmvc.service.EmployeeService;

@Controller
public class EmployeeController {
    
    @Autowired
    private EmployeeService employeeService;
    
    @GetMapping("/employees")
    public String listEmployees(Model model) {
        model.addAttribute("employee", new Employee());
        model.addAttribute("listEmployees",this.employeeService.listEmployees());
        return "employeeForm";
    }
    
    
    @PostMapping("/employee/add")
    public String addPerson(@ModelAttribute("employee") Employee emp) {
        
        if(emp.getId() == 0) {
            this.employeeService.addEmployee(emp);
        } else {
            this.employeeService.updateEmployee(emp);
        }
        return "redirect:/employeeForm";
    }
    
    
    @RequestMapping("/remove/{id}")
    public String removePerson(@PathVariable("id") int id){
        
        this.employeeService.removeEmployee(id);
        return "redirect:/employeeForm";
    }
    
 
    @RequestMapping("/edit/{id}")
    public String editPerson(@PathVariable("id") int id, Model model){
        model.addAttribute("employee", this.employeeService.getEmployeeById(id));
        model.addAttribute("listEmployees", this.employeeService.listEmployees());
        return "employeeForm";
    }
    
}

EmployeeDAOImpl.java

package com.john.springmvc.dao;

import java.util.List;

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

import com.john.springmvc.entity.Employee;

@Repository
public class EmployeeDAOImpl implements EmployeeDAO {
    
    @Autowired
    private SessionFactory sessionFactory;

    @Override
    public void addEmployee(Employee emp) {
        Session session = this.sessionFactory.getCurrentSession();
        session.save(emp);
        System.out.println("Employee saved successfully: " + emp);
    }

    @Override
    public void updateEmployee(Employee emp) {
        Session session = this.sessionFactory.getCurrentSession();
        session.update(emp);
        System.out.println("Employee updated successfully: " + emp);

    }

    @Override
    public List<Employee> listEmployees() {
        Session session = this.sessionFactory.getCurrentSession();
        List<Employee> employeeList = session.createQuery("from Employee").getResultList();
        
        for(Employee emp : employeeList) {
            System.out.println("Employee List: \n" + emp);
        }
        return employeeList;
    }
    

    @Override
    public Employee getEmployeeById(int id) {
        Session session = this.sessionFactory.getCurrentSession();
        Employee emp = session.get(Employee.class, new Integer(id));
        System.out.println("Getting employee with id: " + id);
        return emp;
    }

    @Override
    public void removeEmployee(int id) {
        Session session = this.sessionFactory.getCurrentSession();
        Employee emp = (Employee) session.get(Employee.class, new Integer(id));
        
        if(null != emp) {
            session.delete(emp);
        }
        
        System.out.println("Employee deleted successfully: " + emp);
    }
}

EmployeeServiceImpl.java

package com.john.springmvc.service;

import java.util.List;

import javax.transaction.Transactional;

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

import com.john.springmvc.dao.EmployeeDAO;
import com.john.springmvc.entity.Employee;

@Service
public class EmployeeServiceImpl implements EmployeeService{
    
    @Autowired
    private EmployeeDAO employeeDAO;

    @Override
    @Transactional
    public void addEmployee(Employee emp) {
        this.employeeDAO.addEmployee(emp);
    }

    @Override
    @Transactional
    public void updateEmployee(Employee emp) {
        this.employeeDAO.updateEmployee(emp);
    }

    @Override
    @Transactional
    public List<Employee> listEmployees() {
        return this.employeeDAO.listEmployees();
    }

    @Override
    @Transactional
    public Employee getEmployeeById(int id) {
        return this.employeeDAO.getEmployeeById(id);
    }

    @Override
    @Transactional
    public void removeEmployee(int id) {
        this.employeeDAO.removeEmployee(id);
        
    }
}

查看：employeeForm.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://www.springframework.org/tags" prefix="spring" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>


<head>
    <title>Document</title>
    <link rel="stylesheet" type="text/css" href="${pageContext.request.contextPath}/resources/css/style.css" />
</head>
<body>

    <form action="/spring-mvc-forms/addEmployee" method="POST" modelAttribute="employee" class="form">

        <h1 class="form-heading">Employee Form</h1>

        <label for="employeeID" class="form-label">Employee ID: </label><br>
        <input type="text" path="employeeID" id="employeeId" placeholder="Enter employee id.."/><br><br>

        <label for="firstName" class="form-label">First Name: </label><br>
        <input type="text" path="firstName" id="firstName" placeholder="Enter first name.."/><br><br>

        <label for="lastName" class="form-label">Last Name: </label><br>
        <input type="text" path="lastName" id="lastName" placeholder="Enter last name.."/><br><br>

        <label for="contactNumber" class="form-label">Contact Number: </label><br>
        <input type="text" path="contactNumber" id="contactNumber" placeholder="Enter contact number.."/><br><br>

        <label for="emailAddress" class="form-label">Email Address: </label><br>
        <input type="text" path="emailAddress" id="emailAddress" placeholder="Enter email address.."/><br><br>

        <input type="submit" value="Submit" id="submitButton"/> 
    </form>


    <h3>Employee List</h3>
            <table id="t01">
                <tr>
                  <th>Employee ID</th>
                  <th>First Name</th> 
                  <th>Last Name</th>
                  <th>Contact Number</th>
                  <th>Email Address</th>
                  <th>Edit</th>
                  <th>Delete</th>
                </tr>
        
                <c:forEach items="${listEmployees}" var="employee">
                    <tr>
                        <td>${employee.employeeId}</td>
                        <td>${employee.firstName}</td>
                        <td>${employee.lastName}</td>
                        <td>${employee.contactNumber}</td>
                        <td>${employee.emailAddress}</td>
                        <td><a href="<c:url value='/edit/${employee.id}' />" >Edit</a></td>
                        <td><a href="<c:url value='/remove/${employee.id}' />" >Delete</a></td>
                    </tr>
                </c:forEach>
             </table>

          
</body>
</html>

視圖：employeeView.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Employee Details</title>
 <link rel="stylesheet" type="text/css" href="${pageContext.request.contextPath}/resources/css/style.css" />
</head>
<body>
    <h3>Submitted Employee Information</h3>
    <table>
    
        <tr>
            <td>Employee ID:</td>
            <td>${employeeId}</td>
        </tr>
        
        <tr>
            <td>First Name :</td>
            <td>${firstName}</td>
        </tr>
        
        <tr>
            <td>Last Name :</td>
            <td>${lastName}</td>
        </tr>
        
        <tr>
            <td>Contact Number :</td>
            <td>${contactNumber}</td>
        </tr>
        
        <tr>
            <td>Email Address :</td>
            <td>${emailAddress}</td>
        </tr>
        
    </table>
</body>
</html>

spring-mvc-forms-servlet.xml

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

    <!-- Add support for component scanning -->
    <context:component-scan base-package="com.john.springmvc" />

    <!-- Add support for conversion, formatting and validation support -->
    <mvc:annotation-driven/>

    <!-- Define Spring MVC view resolver -->
    <bean
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/view/" />
        <property name="suffix" value=".jsp" />
    </bean>
    
    
    <!-- Step 1: Define Database DataSource / connection pool -->
    <bean id="myDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="driverClass" value="com.mysql.cj.jdbc.Driver" />
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/spring-mvc-forms?useSSL=false&amp;serverTimezone=UTC" />
        <property name="user" value="root" />
        <property name="password" value="password" /> 

        <!-- these are connection pool properties for C3P0 -->
        <property name="minPoolSize" value="5" />
        <property name="maxPoolSize" value="20" />
        <property name="maxIdleTime" value="30000" />
    </bean>  
    
    <!-- Step 2: Setup Hibernate session factory - DEPENDS ON THE DATA SOURCE -->
    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
        <property name="dataSource" ref="myDataSource" />
        <property name="packagesToScan" value="com.john.springmvc.entity" />
        <property name="hibernateProperties">
           <props>
              <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
              <prop key="hibernate.show_sql">true</prop>
           </props>
        </property>
   </bean>    

    <!-- Step 3: Setup Hibernate transaction manager -->
    <bean id="myTransactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory"/>
    </bean>
    
    <!-- Step 4: Enable configuration of transactional behavior based on annotations -->
    <tx:annotation-driven transaction-manager="myTransactionManager" />
    
    <!-- Step 5: Support for adding web resources: CSS, IMAGES, JS etc -->
    <mvc:resources location="/resources/" mapping="/resources/**"></mvc:resources>

</beans>

網頁.xml

<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-forms</display-name>

  <absolute-ordering />

  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>index.html</welcome-file>
  </welcome-file-list>

  <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-mvc-forms-servlet.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>

Answer 1

您好，此錯誤意味着您的類路徑中沒有 com.mchange.v2.c3p0.ComboPooledDataSource 類。

如果您使用 maven，您應該添加它以將 C3P0 添加到您的項目中。

<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.5.5</version>
</dependency>