如有两个表用户(users) 和角色(role) 他们是多对多关系:
Users:
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
@SuppressWarnings("serial")
@Entity
public class Users implements Serializable {
private Long id;
private String name;
private String password;
private String realName;
private String sex;
private String phone;
private String email;
private Set<Role> roles = new HashSet<Role>();
@Id
@GeneratedValue
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getRealName() {
return realName;
}
public void setRealName(String realName) {
this.realName = realName;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@ManyToMany(fetch=FetchType.EAGER)
@JoinTable(name="usersRoles",joinColumns={@JoinColumn(name="userId",referencedColumnName="id")},inverseJoinColumns={@JoinColumn(name="roleId",referencedColumnName="id")})
public Set<Role> getRoles() {
return roles;
}
public void setRoles(Set<Role> roles) {
this.roles = roles;
}
}
Role:
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
@SuppressWarnings("serial")
@Entity
public class Role implements Serializable {
private Long id;
private String name;
private String description;
private Set<Users> users = new HashSet<Users>();
@Id
@GeneratedValue
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
@ManyToMany(mappedBy="roles")
public Set<Users> getUsers() {
return users;
}
public void setUsers(Set<Users> users) {
this.users = users;
}
}
最终会生成三张表,如下图