SpringBoot2 JPA解决懒加载异常的问题
作者:易水墨龙吟
这篇文章主要介绍了SpringBoot2 JPA解决懒加载异常的问题,具有很好的参考价值,希望对大家有所帮助。一起跟随小编过来看看吧
jpa解决懒加载异常
在我上一遍文章上进行行修改,SpringBoot2 实现JPA分页和排序分页
实体类上改:
@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; } }
控制器验证
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("分页: 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("排序分页: 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; } }
我大概实现了一下,具体的如果大佬找到更好的方法或者发现我的方法是错的,希望各位大佬提醒一下!感谢!
补充:SpringBoot jpa 使用懒加载时,报异常:session失效
报异常:
could not initialize proxy - no Session
1、在方法上加@Transactional 注解,失败
2、在application.yml 文件加上jpa.properties.open-in-view: true 失败
3、在ResourceServerApplication.java 启动文件中加上:
@Bean public OpenEntityManagerInViewFilter openEntityManagerInViewFilter() { return new OpenEntityManagerInViewFilter(); }
成功解决~
总结:
要解决no session 问题需要:
配置文件中加jpa.properties.open-in-view: true同时在启动文件中加@Bean
以上为个人经验,希望能给大家一个参考,也希望大家多多支持脚本之家。如有错误或未考虑完全的地方,望不吝赐教。