使用Angular和Java EE向數據庫添加日期時出錯

Question

對於一個簡單的客戶管理應用程序，我很難添加生日！

這是我的HTML：

<label for="dob" class="firstThreeInputs">Date of Birth: </label>
<input type="date" [(ngModel)]="customer.dateOfBirth" class="" id="dateOfBirthInput" name="dateOfBirth" placeholder="Date of Birth">

當我添加新客戶或編輯現有客戶時，出現以下錯誤：

Failed executing PUT /customers/6: org.jboss.resteasy.spi.ReaderException: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `java.time.LocalDate` (no Creators, like default construct, exist): no String-argument constructor/factory method to deserialize from String value ('2018-12-12')

看來這是一個常見問題，Jackson有解決方案，但我不知道如何在我的應用程序中實現。

以下是我的客戶類別：

 import java.time.LocalDate; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.NamedQuery; import javax.persistence.Table; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule; //Data and Integration @Entity @Table(name ="basic_info") @NamedQuery(name="Customers.selectAll", query="SELECT n From Customers n") public class Customers { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; @Column(length=100, nullable=false) private String first_name; @Column(length=100, nullable=false) private String last_name; @Column(length=100, nullable=false) private String country_code; @Column(length=100, nullable=false) private String gender; @Column(nullable=false) private LocalDate dateOfBirth; @Column(nullable=false) private boolean isActive; public Customers() {} public Customers(Long id, String first_name, String last_name, LocalDate dateOfBirth) { this.id = id; this.first_name = first_name; this.last_name = last_name; this.dateOfBirth = dateOfBirth; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getFirstName() { return first_name; } public void setFirstName(String first_name) { this.first_name = first_name; } public String getLastName() { return last_name; } public void setLastName(String last_name) { this.last_name = last_name; } public LocalDate getDateOfBirth() { return dateOfBirth; } public void setDateOfBirth(LocalDate dateOfBirth) { this.dateOfBirth = dateOfBirth; } public String getCountryCode() { return country_code; } public void setCountryCode(String country_code) { this.country_code = country_code; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public boolean getActiveStatus() { return isActive; } public void setActiveStatus(boolean isActive) { this.isActive = isActive; } @Override public String toString() { return "Cusomters [id=" + id + ", First Name =" + first_name + ", Last Name=" + last_name + " DateOfBirth="+ dateOfBirth +" Gender= " + gender + "CountryCode=" + country_code + "]"; } } 

如何添加Jackson代碼，以便在PUT / POST時將JSON轉換為Java，或者在GET期間反過來轉換為Java？ 如何使用ObjectMapper和JavaTimeModule？

以下是我的客戶資源類：

 package at.technikumwien.webf; import java.net.URI; import java.util.List; import java.util.logging.Logger; import javax.inject.Inject; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.transaction.Transactional; import javax.ws.rs.Consumes; import javax.ws.rs.DELETE; import javax.ws.rs.GET; import javax.ws.rs.POST; import javax.ws.rs.PUT; import javax.ws.rs.Path; import javax.ws.rs.PathParam; import javax.ws.rs.Produces; import javax.ws.rs.WebApplicationException; import javax.ws.rs.core.Context; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.Response; import javax.ws.rs.core.UriInfo; import javax.ws.rs.core.Response.Status; @Path("/customers") @Consumes(MediaType.APPLICATION_JSON) @Produces(MediaType.APPLICATION_JSON) public class CustomersResource { private static final Logger LOGGER = Logger.getLogger(CustomersResource.class.getName()); @PersistenceContext private EntityManager em; @Inject private CustomersService customersService; @Context private UriInfo uriInfo; @POST @Transactional public Response create(Customers customer) { LOGGER.info("create >> customer=" + customer); em.persist(customer); URI uri = uriInfo.getAbsolutePathBuilder().path(customer.getId().toString()).build(); return Response.created(uri).build(); } @PUT @Path("/{id}") @Transactional public void update(@PathParam("id") long id, Customers customerUpdate) { LOGGER.info("update >> id=" + id + ", customer=" + customerUpdate); Customers customerOld = em.find(Customers.class, id); if ( customerOld != null) { customerOld.setFirstName(customerUpdate.getFirstName()); customerOld.setLastName(customerUpdate.getLastName()); customerOld.setDateOfBirth(customerUpdate.getDateOfBirth()); customerOld.setGender(customerUpdate.getGender()); customerOld.setCountryCode(customerUpdate.getCountryCode()); customerOld.setActiveStatus(customerUpdate.getActiveStatus()); } else { throw new WebApplicationException(Status.NOT_FOUND); } } @DELETE @Path("/{id}") @Transactional public void delete(@PathParam("id") long id) { LOGGER.info("delete >> id=" + id); Customers customer = em.find(Customers.class, id); if (customer != null) { em.remove(customer); } else { throw new WebApplicationException(Status.NOT_FOUND); } } @GET @Path("/{id}") public Customers retrieve(@PathParam("id") long id) { LOGGER.info("retrieve id=" + id); return em.find(Customers.class, id); } @GET @Path("/") public List<Customers> retrieveAll() { LOGGER.info("retrieveAll"); return customersService.getAllCustomers(); } } 

Answer 1

正如您的錯誤所解釋的那樣，諸如LocalDate 類的java.time類沒有公共構造函數。 沒有new LocalDate 。 相反，這些類使用工廠方法 ，如這些命名約定所示。

LocalDate today = LocalDate.now() ;  // Tip: Better to pass a `ZoneId`.
LocalDate tomorrow = today.plusDays( 1 ) ;  // Immutable objects. So a new fresh `LocalDate` is instantiated based on values copied from original object. 
LocalDate someDay = LocalDate.parse( "2020-01-23" ) ; 

您的代碼顯然期望使用no-arg構造函數 。 沒找到，當然。

在Stack Overflow上已經多次討論了使用Jackson來處理LocalDate的主題。

Answer 2

我找到了一個精彩的博客，它解釋了這一點：

https://kodejava.org/how-to-format-localdate-object-using-jackson/