SpringBoot2 JPA解決懶加載異常的問題

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jpa解決懶加載異常

在我上一遍文章上進行行修改，SpringBoot2 實現JPA分頁和排序分頁

實體類上改：

@Entity
@Table(name = "employee")
@JsonIgnoreProperties(value={"hibernateLazyInitializer", "department"})
public class Employee {
 @Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)
 private Integer empId;
 private String lastName;
 private String email;
 @Temporal(TemporalType.DATE)
 private Date birth;
 @Temporal(TemporalType.TIMESTAMP)
 private Date createTime;
 @ManyToOne(fetch = FetchType.LAZY)
 @JoinColumn(name = "dept_id")
 private Department department;
 public Integer getEmpId() {
  return empId;
 }
 public void setEmpId(Integer empId) {
  this.empId = empId;
 }
 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;
 }
 public Date getBirth() {
  return birth;
 }
 public void setBirth(Date birth) {
  this.birth = birth;
 }
 public Date getCreateTime() {
  return createTime;
 }
 public void setCreateTime(Date createTime) {
  this.createTime = createTime;
 }
 public Department getDepartment() {
  return department;
 }
 public void setDepartment(Department department) {
  this.department = department;
 }
}

控制器驗證

import java.util.Iterator;
@RestController
public class EmployeeController {
 @Autowired
 private EmployeeService employeeService;
 @GetMapping("/emp")
 public Page<Employee> showPage(@RequestParam(value = "page") Integer page, @RequestParam(value = "size") Integer size){
  System.out.println("分頁： page:"+page+"; size:"+size);
  return employeeService.getPage(page, size);
 }
 @GetMapping("/emp_sort")
 public Page<Employee> showSortPage(@RequestParam(value = "page") Integer page, @RequestParam(value = "size") Integer size){
  System.out.println("排序分頁： page:"+page+"; size:"+size);
  Page<Employee> list = employeeService.getPageSort(page, size);
  Iterator<Employee> it=list.iterator();
  while(it.hasNext()){
   System.out.println("value:"+(it.next()).getDepartment().getDeptName());
  }
  return list;
 }
}

我大概實現瞭一下，具體的如果大佬找到更好的方法或者發現我的方法是錯的，希望各位大佬提醒一下！感謝！

補充：SpringBoot jpa 使用懶加載時，報異常：session失效

報異常:

could not initialize proxy – no Session

1、在方法上加@Transactional 註解，失敗

2、在application.yml 文件加上jpa.properties.open-in-view: true 失敗

3、在ResourceServerApplication.java 啟動文件中加上：

 @Bean
 public OpenEntityManagerInViewFilter openEntityManagerInViewFilter() {
   return new OpenEntityManagerInViewFilter();
 }

成功解決~

總結：

要解決no session 問題需要：

配置文件中加jpa.properties.open-in-view: true同時在啟動文件中加@Bean

以上為個人經驗，希望能給大傢一個參考，也希望大傢多多支持WalkonNet。如有錯誤或未考慮完全的地方，望不吝賜教。

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