使用带休眠后端的 JAX-RS 执行 POST 请求时出现 class 强制转换异常

Question

我有一个简单的User POJO class，它的定义如下：

package models;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@Entity
@XmlRootElement
@Table(name="USER",uniqueConstraints={@UniqueConstraint(columnNames="email")})
public class User {
@XmlElement
private String name;
@Id
@XmlElement
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
@XmlElement
private String email;
@XmlElement
private int age;
@Override
public String toString() {
    return "User [name=" + name + ", id=" + id + ", email=" + email + ", age=" + age + "]";
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getEmail() {
    return email;
}
public void setEmail(String email) {
    this.email = email;
}
public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}

}

而我的资源映射如下：

@POST
@Produces(MediaType.TEXT_HTML)
@Consumes(MediaType.APPLICATION_JSON)
@Path("/Person")
public Response insertPerson(User user) {
    SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
    Session session = sessionFactory.openSession();
    Transaction tx = session.beginTransaction();
    int uid = (Integer)session.save(user);
    tx.commit();
    session.close();
    return Response.status(201).entity(uid).build();


}

当我使用 PostMan 执行 post 请求时，我在服务器上收到此异常：

Dec 20, 2015 9:44:42 AM org.apache.catalina.core.StandardWrapperValve    invoke
SEVERE: Servlet.service() for servlet [Jersey Web Application] in    context with path [/expenseManagement] threw exception [Exception [EclipseLink-6065] (Eclipse Persistence Services - 2.6.0.v20150309-bf26070): org.eclipse.persistence.exceptions.QueryException
Exception Description: Cannot add the object [User [name=manjunath, id=100, email=manjunath@gmail.com, age=15]], of class [class models.User], to container [class models.User].
Internal Exception: java.lang.ClassCastException: models.User cannot be cast to java.util.Collection] with root cause
java.lang.ClassCastException: models.User cannot be cast to java.util.Collection

我也提供了消息正文阅读器，我不知道我哪里错了，有人可以帮忙吗。

Answer 1

您发送的内容被 [ 和 ] 包围，将其标记为数组，而不是对象。尝试只发送这个字符串：

 {"name":"manjunath", "age":15, "id":100, "email":"manjunath@gmail.com"}

祝你好运

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