JSP 页提交的输入路径 ID 始终被@ModelAttribute解释为零，因此无法更新模型对象

Question

我正在用Spring和Hibernate做一个crud操作项目。下面是模型类。

员工.java

@Entity
@Table(name="employee")
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
private String password;
private String gender;
private String city;
//getters and setters }

以下是员工DaoImpl.java：

import com.anand.model.Employee;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.List;
//implementation of Dao Layer
public class EmployeeDaoImpl implements EmployeeDao {
private static final Logger LOGGER = LoggerFactory.getLogger(EmployeeDaoImpl.class);
private SessionFactory sessionFactory;
public SessionFactory getSessionFactory() {
return sessionFactory;
}
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
public Session getSession() {
return getSessionFactory().openSession();
}
@Override
public void addEmployee(Employee employee) {
//Find out why the save is working but not persist
getSession().save(employee);
LOGGER.info("Employee " + employee + " added.");
}
@Override
public void updateEmployee(Employee employee) {
getSession().update(employee);
LOGGER.info("Employee " + employee + " updated.");
}
@Override
public Employee getEmployeeById(int id) {
Employee employee = (Employee) getSession().load(Employee.class, id);
LOGGER.info("Got Employee " + employee);
return employee;
}
@SuppressWarnings({"unchecked", "JpaQlInspection"})
@Override
public List<Employee> listEmployees() {
List<Employee> employeeList = getSession().createQuery("from Employee").list();
for (Employee employee : employeeList) {
LOGGER.info("Employee list " + employee);
}
return employeeList;
}
@Override
public void deleteEmployeeById(int id) {
Employee employee = (Employee) getSession().load(Employee.class, id);
if (employee != null) {
getSession().delete(employee);
}
LOGGER.info("deleted " + employee);
}
}

以下是EmployeeServiceImpl.java：

package com.anand.service;
import java.util.List;
import com.anand.dao.EmployeeDao;
import com.anand.model.Employee;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;
public class EmployeeServiceImpl implements EmployeeService {
@Autowired
private EmployeeDao employeeDao;
public EmployeeDao getEmployeeDao() {
return employeeDao;
}
public void setEmployeeDao(EmployeeDao employeeDao) {
this.employeeDao = employeeDao;
}
@Override
@Transactional
public void addEmployee(Employee employee) {
getEmployeeDao().addEmployee(employee);
}
@Override
@Transactional
public void updateEmployee(Employee employee) {
getEmployeeDao().updateEmployee(employee);
}
@Override
@Transactional
public Employee getEmployeeById(int id) {
return getEmployeeDao().getEmployeeById(id);
}
@Override
@Transactional
public List<Employee> listEmployees() {
return getEmployeeDao().listEmployees();
}
@Override
@Transactional
public void deleteEmployeeById(int id) {
getEmployeeDao().deleteEmployeeById(id);
}
}

下面是通过依赖关系注入注入 employeeService 的控制器类方法。

@RequestMapping(value = {"/","/home"})
public ModelAndView homePage() {
return new ModelAndView("home");
}
@RequestMapping(value = "/register", method = RequestMethod.POST)
public String registerEmployeePost(@ModelAttribute("employee") Employee employee, ModelMap modelMap) {
System.out.println(employee);
if (employee.getId() == 0) {
System.out.println("adding employee");
getEmployeeService().addEmployee(employee);
} else {
System.out.println("updating employee");
getEmployeeService().updateEmployee(employee);
}
return "redirect:/register";
}
@RequestMapping(value = "/register", method = RequestMethod.GET)
public String registerEmployeeGet(@ModelAttribute("employee") Employee employee, ModelMap modelMap) {
modelMap.addAttribute("employeesList", getEmployeeService().listEmployees());
return "result";
}
@RequestMapping(value = "/edit/{id}")
public String editEmployee(@PathVariable("id") int id, Model model) {
Employee employee = getEmployeeService().getEmployeeById(id);
if (employee != null) {
model.addAttribute("employee", employee);
} else {
System.out.println("####employee by this id not found####");
}
return "home";
}

以下是 JSP 文件主页：

<c:url var="addAction" value="/register"/>
<form:form action="${addAction}" commandName="employee" method="post"  cssClass="form-horizontal">
<label for="id" class="col-sm-2 control-label">ID: </label>
<form:input path="id" readonly="true" cssClass="form-control" disabled="true"/>
<label for="name" class="col-sm-2 control-label">Name: </label>
<form:input path="name" cssClass="form-control"/>
<label for="password" class="col-sm-2 control-label">Password: </label>
<form:input path="password" cssClass="form-control"/>
<label for="gender" class="col-sm-2 control-label">Gender: </label>
<form:input path="gender" cssClass="form-control"/>
<label for="city" class="col-sm-2 control-label">City: </label>
<form:input path="city" cssClass="form-control"/>
<input type="submit" value="Submit" class="btn btn-lg btn-primary"/>
</form:form>

最后，弹簧配置.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:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
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">
<mvc:annotation-driven/>
<context:annotation-config/>
<context:component-scan base-package="com.anand"/>
<bean class="org.apache.commons.dbcp.BasicDataSource" id="dataSource" destroy-method="close">
<property name="driverClassName" value="org.postgresql.Driver"/>
<property name="url" value="jdbc:postgresql://localhost:5432/test"/>
<property name="username" value="postgres"/>
<property name="password" value="abc@1234"/>
</bean>
<bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="annotatedClasses">
<list>
<value>com.anand.model.Employee</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.PostgreSQL82Dialect</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.hbm2ddl.auto">create</prop>
</props>
</property>
</bean>
<bean class="com.anand.dao.EmployeeDaoImpl" id="employeeDao">
<property name="sessionFactory" ref="sessionFactory"/>
</bean>
<bean class="com.anand.service.EmployeeServiceImpl" id="employeeService">
<property name="employeeDao" ref="employeeDao"/>
</bean>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp" />
</bean>
<!--For @Transactional-->
<tx:annotation-driven transaction-manager="transactionManager"/>
<bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory"/>
</bean>
</beans>

我有两个问题，首先，当我使用 persist() 而不是 save() 时，对象不会被保存。其次，当我尝试通过点击/edit/{id} url 并传递它的 id(控制器通过它获取 employeeById)来更新模型时，表单会由正确的条目填充，提交后，一个新条目被添加到具有新 ID 的员工列表中。 我查看了日志，发现 id 总是以 0/register出现。我不知道为什么！请协助。

编辑：现在，id正确出现，但即使我收到成功的LOGGER消息，对象仍然没有更新。

Answer 1

您将 id 输入设置为disabled="true"，因此您可以在此处看到，如果禁用输入元素，它将无法接收用户输入，并且其值将不会随表单一起提交。

我建议您尝试包含hiddencss类而不是禁用属性。这应该可以解决您的问题，因为 id 将被发送到服务器端，它将更新元素而不是创建一个新元素。

希望对您有所帮助，

Answer 2

事实证明，我打电话给sessionFactory().openSession()，我从未关闭过。相反，我应该调用sessionFactory().getCurrentSession()来获取当前会话。

也请看这里。openSession() 和 getCurrentSession() 之间的区别