一對一外鍵

Question

我的項目中存在一對一外鍵關系映射的問題。

User.java

@Access(AccessType.FIELD)
@Entity
@Table(name = "users")
public class User {
public Role ro;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
public int user_id;
@Column(name = "username")
public String username;
@Column(name = "password")
public String password;


@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "username")
public Role getRo() {
    return ro;
}

public void setRo(Role ro) {
    this.ro = ro;
}

@Column(name = "enabled")

public int enabled;


public User() {
}

public int getUser_id() {
    return user_id;
}

public User(String username, String password, int enabled) {
    this.username = username;
    this.password = password;
    this.enabled = enabled;

}


public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

public int getEnabled() {
    return enabled;
}

public void setEnabled(int enabled) {
    this.enabled = enabled;
}



@Override
public String toString() {
    return String.format(
            "student[id=%d, name='%s', age='%d']",
            ro.getUsername(), username, ro.getUsername());
}

}

Role.java

import javax.persistence.*;

@Access(AccessType.FIELD)
@Entity
@Table(name = "user_roles")
public class Role {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
public int user_role_id;
@Column(name = "username")
public String username;
@Column(name = "role")
public String role;

public User user;


@OneToOne(mappedBy = "ro")
public User getUser() {
    return user;
}

public void setUser(User user) {
    this.user = user;
}



public Role(String username, String role) {
    this.username = username;
    this.role = role;
}

public Role() {
}

public int getUser_role_id() {
    return user_role_id;
}



public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public String getRole() {
    return role;
}

public void setRole(String role) {
    this.role = role;
}



}

這是錯誤：

原因：org.hibernate.MappingException：無法確定com.company.project.models.Role的類型，在表：用戶處，對於列：在org.hibernate的[org.hibernate.mapping.Column（ro）]。 mapping.SimpleValue.getType（SimpleValue.java:431）〜[hibernate-core-5.0.12.Final.jar：5.0.12.Final] at org.hibernate.mapping.SimpleValue.isValid（SimpleValue.java:398）〜 [hibernate-core-5.0.12.Final.jar：5.0.12.Final] at org.hibernate.mapping.Property.isValid（Property.java:225）〜[hibernate-core-5.0.12.Final.jar：在org.hibernate.mapping.PersistentClass.validate（PersistentClass.java:595）的[5.0.12.Final]〜在org.hibernate.mapping的[hibernate-core-5.0.12.Final.jar：5.0.12.Final]。 RootClass.validate（RootClass.java:265）〜[hibernate-core-5.0.12.Final.jar：5.0.12.Final] at org.hibernate.boot.internal.MetadataImpl.validate（MetadataImpl.java:329）〜 [hibernate-core-5.0.12.Final.jar：5.0.12.Final] at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build（SessionFactoryBuilderImpl.java:443）〜[hibernate-core-5.0.12.Final。 Ĵ ar：5.0.12.Final]位於org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build（EntityManagerFactoryBuilderImpl.java:879）〜[hibernate-entitymanager-5.0.12.Final.jar：5.0.12.Final]。 .. 22個共同的框架被省略

Answer 1

您應該在變量聲明或getter()上注釋所有@Column / @OneToOne 。 這就是為什么休眠在class User找不到Role原因。