我写了一个项目，您可以在其中添加和编辑学生。我有一个学生列表，除编辑外，所有功能均有效。我想更改姓名和姓名，头像学生，但不起作用。可以看到代码，我想我写的都正确，为什么编辑学生的功能不起作用
学生控制器
package adil.java.schoolmaven.controller;
@Controller
public class StudentController {
@Autowired
private ServletContext servletContext;
// Constructor based Dependency Injection
private StudentService studentService;
public StudentController() {
}
@Autowired
public StudentController(StudentService studentService) {
this.studentService = studentService;
}
@RequestMapping(value = "/allStudents", method = {RequestMethod.GET, RequestMethod.POST})
public ModelAndView displayAllUser() {
System.out.println("User Page Requested : All Students");
ModelAndView mv = new ModelAndView();
List<Student> studentList = studentService.getAllStudents();
mv.addObject("studentList", studentList);
mv.setViewName("allStudents");
return mv;
}
@RequestMapping(value = "/addStudent", method = RequestMethod.GET)
public ModelAndView displayNewUserForm() {
ModelAndView mv = new ModelAndView("addStudent");
mv.addObject("headerMessage", "Add Student Details");
mv.addObject("student", new Student());
return mv;
}
@PostMapping(value = "/addStudent")
public String saveNewStudent(@RequestParam("name") @NonNull String name,
@RequestParam("surname") @NonNull String surname,
@RequestParam("avatar") MultipartFile file)
throws IOException {
Student student = new Student();
student.setSurname(surname);
student.setName(name);
if (file != null && !file.isEmpty()) {
student.setAvatar(studentService.saveAvatarImage(file).getName());
}
studentService.saveStudent(student);
return "redirect:/allStudents";
}
@GetMapping(value = "/editStudent/{id}")
public ModelAndView displayEditUserForm(@PathVariable Long id) {
ModelAndView mv = new ModelAndView("editStudent");
Student student = studentService.getStudentById(id);
mv.addObject("headerMessage", "Редактирование студента");
mv.addObject("student", student);
return mv;
}
@PostMapping(value = "/editStudent")
public String saveEditedUser(
@RequestParam("id") Long id,
@RequestParam("name") String name,
@RequestParam("surname") String surname,
@RequestParam("avatar") MultipartFile file) {
try {
studentService.updateStudent(name, surname, file, studentService.getStudentById(id));
} catch (FileSystemException ex) {
ex.printStackTrace();
} catch (IOException e) {
return "redirect:/error";
}
return "redirect:/allStudents";
}
@GetMapping(value = "/deleteStudent/{id}")
public ModelAndView deleteUserById(@PathVariable Long id) {
studentService.deleteStudentById(id);
ModelAndView mv = new ModelAndView("redirect:/allStudents");
return mv;
}
}
编辑学生JSP
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/js/bootstrap.min.js"></script>
<title>Home</title>
</head>
<body>
<center>
<h1>${headerMessage}</h1>
<form:form method="POST" action="${pageContext.request.contextPath}/editStudent" enctype="multipart/form-data">
<table>
<input type="hidden" value="${student.id}" name="id"/>
<tr>
<td><label path="Name">Name</label></td>
<td><input type="text" name="name" value="${student.name}"/></td>
</tr>
<tr>
<td><label path="Surname">Surname</label></td>
<td><input name="surname" value="${student.surname}"/></td>
</tr>
<tr>
<td><label path="Avatar">Avatar:</label></td>
<td>
<img src="${pageContext.request.contextPath}/avatar?avatar=${student.avatar}"
style="max-height: 200px; max-width: 200px;"/>
</td>
<td>
<input type="file" name="avatar"/>
</td>
</tr>
<tr>
<td><input class="btn btn-primary" type="submit" value="Save"></td>
</tr>
</table>
</form:form>
</center>
</body>
</html>
学生服务
package adil.java.schoolmaven.service;
import java.util.List;
import adil.java.schoolmaven.entity.Student;
import java.io.File;
import java.io.IOException;
import org.springframework.web.multipart.MultipartFile;
public interface StudentService {
List<Student> getAllStudents();
Student getStudentById(Long id);
boolean saveStudent(Student student);
boolean deleteStudentById(Long id);
File loadAvatarByFileName(String filename);
File saveAvatarImage(MultipartFile avatarImage) throws IOException;
Student updateStudent(String name, String surname, MultipartFile avatar, Student targetStudent) throws IOException;
}
学生服务Impl
package adil.java.schoolmaven.service;
import java.util.ArrayList;
import java.util.List;
import javax.transaction.Transactional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import adil.java.schoolmaven.entity.Student;
import adil.java.schoolmaven.repository.StudentRepository;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.multipart.MultipartFile;
@Service
@Transactional
public class StudentServiceImpl implements StudentService {
@Value("${storage.location}")
private String storageLocation;
private StudentRepository repository;
public StudentServiceImpl() {
}
@Autowired
public StudentServiceImpl(StudentRepository repository) {
super();
this.repository = repository;
}
@Override
public List<Student> getAllStudents() {
List<Student> list = new ArrayList<Student>();
repository.findAll().forEach(e -> list.add(e));
return list;
}
@Override
public Student getStudentById(Long id) {
Student student = repository.findById(id).get();
return student;
}
@Override
public boolean saveStudent(Student student) {
try {
repository.save(student);
return true;
} catch (Exception ex) {
return false;
}
}
@Override
public boolean deleteStudentById(Long id) {
try {
repository.deleteById(id);
return true;
} catch (Exception ex) {
return false;
}
}
@Override
public File loadAvatarByFileName(String filename) {
return new File(storageLocation + "/" + filename);
}
@Override
public File saveAvatarImage(MultipartFile avatarImage) throws IOException {
File newFile = File.createTempFile(
avatarImage.getName(),
"." + avatarImage.getOriginalFilename().split("\\.")[1],
new File(storageLocation));
avatarImage.transferTo(newFile);
return newFile;
}
@Override
public Student updateStudent(String name, String surname, MultipartFile avatar, Student targetStudent)
throws IOException {
if (name != null && !name.equals(targetStudent.getName())) {
targetStudent.setName(name);
}
if (surname != null && !surname.equals(targetStudent.getSurname())) {
targetStudent.setSurname(surname);
}
String oldAvatarName = targetStudent.getAvatar();
if (oldAvatarName != null) {
Files.deleteIfExists(Paths.get(storageLocation + File.separator + oldAvatarName));
}
File newAvatar = null;
if (avatar != null) {
newAvatar = saveAvatarImage(avatar);
assert newAvatar != null;
targetStudent.setAvatar(newAvatar.getName());
}
boolean isSaved = saveStudent(targetStudent);
if (!isSaved) {
throw new IOException();
}
Files.deleteIfExists(Paths.get(storageLocation + File.separator + oldAvatarName));
return targetStudent;
}
}
我添加了学生资料库
package adil.java.schoolmaven.repository;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import adil.java.schoolmaven.entity.Student;
@Repository
public interface StudentRepository extends CrudRepository<Student, Long>{
}
答案 0 :(得分：0)
从StudentServiceImpl updateStudent代码中，我可以看到您没有碰到存储库，一旦使用update方法更新了现有学生的值，就必须使用repository.save（object）保存更新后的值，已经使用存储库执行了一些数据库操作，因此您必须将更新的对象保存到数据库。