Java EE 7 Restful Web Service POST方法需要ID类型Autoincrement

Question

我正在使用本教程使用Netbean 7.3.1创建简单的Java EE 7 Web服务。

它运行成功，我正在使用GET、PUT、POST、DELETE进行测试。除POST外，这三个都运行良好。

我发布了这个带有ID的json数据，它运行良好。

{"id":"2","address1":"pe3","address2":"address line1","address3":"Address line3","city":"City Name","town":"Town Name","country":"uk","postcode":"123123"}

但因为我的ID是自动递增的，所以当我在没有ID的json后面POST时，它失败了，并出现以下错误

{"address1":"pe3","address2":"address line1","address3":"Address line3","city":"City Name","town":"Town Name","country":"uk","postcode":"123123"}

错误是

HTTP Status 400 - Bad Request
type Status report
messageBad Request
descriptionThe request sent by the client was syntactically incorrect.
GlassFish Server Open Source Edition 4.0

有人能解释一下为什么我在发送POST时需要发送数据库中自动递增类型的ID吗？周围有工作吗？

实体类中的代码是

.......
        @Id
        @Basic(optional = false)
        @NotNull
        @Column(name = "id")
        private Integer id;
        @Size(max = 45)
        @Column(name = "address1")
        private String address1;
        @Size(max = 45)
        @Column(name = "address2")
........

而AddressFacadeREST.java类看起来是这样的。

package entities.service;
import entities.Address;
import java.util.List;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
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;

@Stateless
@Path("entities.address")
public class AddressFacadeREST extends AbstractFacade<Address> {
    @PersistenceContext(unitName = "CustomerDBPU")
    private EntityManager em;
    public AddressFacadeREST() {
        super(Address.class);
    }
    @POST
    @Override
    @Consumes({"application/xml", "application/json"})
    public void create(Address entity) {
        super.create(entity);
    }
    @PUT
    @Override
    @Consumes({"application/xml", "application/json"})
    public void edit(Address entity) {
        super.edit(entity);
    }
    @DELETE
    @Path("{id}")
    public void remove(@PathParam("id") Integer id) {
        super.remove(super.find(id));
    }
    @GET
    @Path("{id}")
    @Produces({"application/xml", "application/json"})
    public Address find(@PathParam("id") Integer id) {
        return super.find(id);
    }
    @GET
    @Override
    @Produces({"application/xml", "application/json"})
    public List<Address> findAll() {
        return super.findAll();
    }
    @GET
    @Path("{from}/{to}")
    @Produces({"application/xml", "application/json"})
    public List<Address> findRange(@PathParam("from") Integer from, @PathParam("to") Integer to) {
        return super.findRange(new int[]{from, to});
    }
    @GET
    @Path("count")
    @Produces("text/plain")
    public String countREST() {
        return String.valueOf(super.count());
    }
    @Override
    protected EntityManager getEntityManager() {
        return em;
    }
}

Answer 1

错误是由于jax-rs服务无法将提供的json转换为实体类的实例而产生的。根据NetBeans创建实体类和服务外观的方式，实体类只有一个非空构造函数，它需要id作为输入参数。此外，在@Id类中还有一个@NotNull注释。如果是：

• 创建一个构造函数，该构造函数接受除@Id属性之外的所有实体属性。通过这种方式，服务将能够将传入的json转换为实体类的实例
• 删除@NotNull注释，以避免JavaBeans Validator在持久化新实体时引发错误