公司实体
@Entity
@Table(name="company")
public class Company implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private int id;
@Column(name="company_id")
private int cmpId;
@Column(name="company_name")
private String companyName;
@OneToOne(fetch=FetchType.LAZY, mappedBy="company")
private Employee employee;
}
员工实体
@Entity
@Table(name="employee")
public class Employee implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private int id;
@Column(name="emp_id")
private int empId;
@Column(name="emp_name")
private String empName;
@OneToOne(fetch=FetchType.LAZY)
@JoinColumn(name="cmp_id", referencedColumnName="company_id")
private Company company;
}
公司服务
@Service
public class CompanyService {
@Autowired
private CompanyRepository companyRepo;
public Company fetchCompany(int cmpId){
System.out.println("11111111111111111");
return companyRepo.findByCmpId(cmpId);
}
}
公司回购
public interface CompanyRepository extends JpaRepository<Company, Integer>{
@Query(value="select a from Company a join fetch a.employee where a.cmpId = ?1")
public Company findByCmpId(int cmpId);
}
API
@RequestMapping("/cmp/{cmpId}")
public void findCmp(@PathVariable int cmpId){
Company cmp = cmpService.fetchCompany(cmpId);
System.out.println(cmp.getEmployee().getEmpName());
}
问题是当我尝试执行我的代码时，我收到以下错误：
Hibernate: select company0_.id as id1_1_0_, employee1_.id as id1_2_1_, company0_.company_id as company_2_1_0_, company0_.company_name as company_3_1_0_, employee1_.cmp_id as cmp_id4_2_1_, employee1_.emp_id as emp_id2_2_1_, employee1_.emp_name as emp_name3_2_1_ from company company0_ inner join employee employee1_ on company0_.id=employee1_.cmp_id where company0_.company_id=?
2017-04-21 17:22:11.386 ERROR 10766 --- [nio-8105-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.orm.jpa.JpaSystemException: Error accessing field [private int com.example.domain.Company.cmpId] by reflection for persistent property [com.example.domain.Company#cmpId] : 1; nested exception is org.hibernate.property.access.spi.PropertyAccessException: Error accessing field [private int com.example.domain.Company.cmpId] by reflection for persistent property [com.example.domain.Company#cmpId] : 1] with root cause
java.lang.IllegalArgumentException: Can not set int field com.example.domain.Company.cmpId to java.lang.Integer
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167) ~[na:1.8.0_91]
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171) ~[na:1.8.0_91]
at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58) ~[na:1.8.0_91]
at sun.reflect.UnsafeIntegerFieldAccessorImpl.getInt(UnsafeIntegerFieldAccessorImpl.java:56) ~[na:1.8.0_91]
at sun.reflect.UnsafeIntegerFieldAccessorImpl.get(UnsafeIntegerFieldAccessorImpl.java:36) ~[na:1.8.0_91]
at java.lang.reflect.Field.get(Field.java:393) ~[na:1.8.0_91]
如何解决这个问题？此外，当我删除 referenceColumnName 时，错误将被删除，但是它们正在加入公司类的主键，我不想这样做。
答案 0 :(得分：2)
这看起来有点时髦，但我相信它的工作方式与您的要求相同。
公司
@Entity
@Table(name = "company")
public class Company implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private Integer id;
@Column(name = "comp_id")
private Integer compId;
@Column(name = "company_name")
private String companyName;
@OneToOne
@JoinColumn(name="emp_id", referencedColumnName="emp_id")
private Employee employee;
@PostPersist
public void postPersist() {
if (id != null && compId == null) {
setCompId(new Integer(id));
}
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getCompanyName() {
return companyName;
}
public void setCompanyName(String companyName) {
this.companyName = companyName;
}
public Employee getEmployee() {
return employee;
}
public void setEmployee(Employee employee) {
this.employee = employee;
}
public Integer getCompId() {
return compId;
}
public void setCompId(Integer compId) {
this.compId = compId;
}
}
<强> CompanyRepository
public interface CompanyRepository extends JpaRepository<Company, Integer> {
@Query(value = "select a from Company a join fetch a.employee as emp where a.compId = ?1")
public Company findByCmpId(int cmpId);
}
<强> CompanyService
@Service
public class CompanyService {
@Autowired
private CompanyRepository companyRepo;
public Company fetchCompany(int cmpId) {
return companyRepo.findByCmpId(cmpId);
}
}
<强>员工
@Entity
@Table(name = "employee")
public class Employee implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private Integer id;
@Column(name = "emp_id")
private Integer empId;
@Column(name = "emp_name")
private String empName;
@OneToOne
@JoinColumn(name="comp_id", referencedColumnName="comp_id")
private Company company;
@PostPersist
public void postPersist() {
if (id != null && empId == null) {
setEmpId(new Integer(id));
}
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getEmpId() {
return empId;
}
public void setEmpId(Integer empId) {
this.empId = empId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public Company getCompany() {
return company;
}
public void setCompany(Company company) {
this.company = company;
}
}
<强> EmployeeRepository
public interface EmployeeRepository extends JpaRepository<Employee, Integer>
{
@Query(value = "select a from Employee a join fetch a.company as comp where a.empId = ?1")
public Employee findByEmpId(int cmpId);
}
<强>的EmployeeService
@Service
public class EmployeeService {
@Autowired
private EmployeeRepository employeeRepo;
public Employee fetchEmployee(int empId) {
return employeeRepo.findByEmpId(empId);
}
}
单元测试
@RunWith(SpringRunner.class)
@SpringBootTest
public class RnlApplicationTests {
@Autowired
CompanyService companyService;
@Autowired
EmployeeService employeeService;
@Autowired
CompanyRepository companyRepository;
@Autowired
EmployeeRepository employeeRepository;
@Before
public void setup() {
Employee employee = new Employee();
employee.setEmpName("Test Employee");
Company company = new Company();
company.setCompanyName("Test Company");
company = companyRepository.save(company);
employee.setCompany(company);
employee = employeeRepository.save(employee);
company.setEmployee(employee);
company = companyRepository.save(company);
Employee employee2 = new Employee();
employee2.setEmpName("Test Employee2");
Company company2 = new Company();
company2.setCompanyName("Test Company2");
company2 = companyRepository.save(company2);
employee2.setCompany(company2);
employee2 = employeeRepository.save(employee2);
company2.setEmployee(employee2);
company2 = companyRepository.save(company2);
}
@Test
public void testRepository() {
Company company = companyService.fetchCompany(1);
assertThat(company).isNotNull();
Company company2 = companyService.fetchCompany(2);
assertThat(company2).isNotNull();
Employee employee = employeeService.fetchEmployee(1);
assertThat(employee).isNotNull();
Employee employee2 = employeeService.fetchEmployee(2);
assertThat(employee2).isNotNull();
}
}
测试的设置有点重复，但我不得不设置它以使这些测试用例正常工作。你可能想出一个更好的方法。
来自公司测试的Hibernate SQL输出
select
company0_.id as id1_0_2_,
company0_.comp_id as comp_id2_0_2_,
company0_.company_name as company_3_0_2_,
company0_.emp_id as emp_id4_0_2_,
employee1_.id as id1_1_0_,
employee1_.comp_id as comp_id4_1_0_,
employee1_.emp_id as emp_id2_1_0_,
employee1_.emp_name as emp_name3_1_0_,
company2_.id as id1_0_1_,
company2_.comp_id as comp_id2_0_1_,
company2_.company_name as company_3_0_1_,
company2_.emp_id as emp_id4_0_1_
from
company company0_
left outer join
employee employee1_
on company0_.emp_id=employee1_.emp_id
left outer join
company company2_
on employee1_.comp_id=company2_.comp_id
where
company0_.comp_id=?
来自Employee test的Hibernate SQL输出
select
employee0_.id as id1_1_0_,
company1_.id as id1_0_1_,
employee0_.comp_id as comp_id4_1_0_,
employee0_.emp_id as emp_id2_1_0_,
employee0_.emp_name as emp_name3_1_0_,
company1_.comp_id as comp_id2_0_1_,
company1_.company_name as company_3_0_1_,
company1_.emp_id as emp_id4_0_1_
from
employee employee0_
inner join
company company1_
on employee0_.comp_id=company1_.comp_id
where
employee0_.emp_id=?
答案 1 :(得分：1)
例外：
IllegalArgumentException: Can not set int field com.example.domain.Company.cmpId to java.lang.Integer
如果是id字段，请使用公司instead的整数int和我们的员工实体。
@Id
@GeneratedValue
private Integer id;
另外，请为您实体中的字段提供getter和setter方法。
答案 2 :(得分：1)
for (int i = 0; i < routedataArray.length(); i++) {
JSONObject jsonObject, studentobject;
JSONArray studentArray;
try {
jsonObject = routedataArray.getJSONObject(i);
ch_list = new ArrayList<studentData>();
stopNum = generalFunc.getStringFromJobject(jsonObject, "stopNum");
stopName = generalFunc.getStringFromJobject(jsonObject, "stopName");
stopLoc = generalFunc.getStringFromJobject(jsonObject, "loc");
studentArray = jsonObject.getJSONArray("students");
for (int j = 0; j < studentArray.length(); j++) {
studentobject = studentArray.getJSONObject(j);
studentName = generalFunc.getStringFromJobject(studentobject, "studentName");
studentId = generalFunc.getStringFromJobject(studentobject, "studentId");
studentData ch = new studentData(studentName,studentId);
ch_list.add(ch);
}
routedata gru = new routedata(stopNum,stopName,stopLoc,ch_list);
list.add(gru);
} catch (JSONException e) {
e.printStackTrace();
}
}