解决使用@ManyToMany查询数据时的死循环问题

package com.example.demo.entity;
import lombok.Data;  
import javax.persistence.*;
import java.util.Set;
 
/**
 * @author lidai
 * @date 2018/10/23 13:53
 */
@Entity
@Data
@Table(name = "t_user")
public class User {
 
    @Id
    private String userId; 
    private String username; 
    private String password;
 
    @ManyToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER)
    @JoinTable(name = "t_user_role",
            joinColumns = @JoinColumn(name = "user_id",referencedColumnName = "user_id"),
            inverseJoinColumns = @JoinColumn(name = "role_id",referencedColumnName = "role_id"))
    private Set<Role> roleSet;  
}

package com.example.demo.entity; 
import com.fasterxml.jackson.annotation.JsonIgnore;
import lombok.Data; 
import javax.persistence.*;
import java.util.Set;
 
/**
 * @author lidai
 * @date 2018/10/29 14:15
 */
@Entity
@Table(name = "t_role")
@Data
@EqualsAndHashCode(exclude = {"userSet"})
public class Role {
 
    @Id
    @GeneratedValue
    private String roleId; 
    private String roleName; 
    private String remark;
 
    @JsonIgnore
    @ManyToMany(fetch = FetchType.LAZY,mappedBy = "roleSet")
    private Set<User> userSet; 
}

    @JsonIgnore
    @ManyToMany(fetch = FetchType.LAZY,mappedBy = "roleSet")
    private Set<User> userSet;

    //角色单向多对多:配置中间表
    //多对多:一个员工可以拥有多个角色，一个角色可以对应多个员工
    @ManyToMany(fetch = FetchType.LAZY)//配置懒加载
    //JoinTable是中间表表名，joinColumns指定中间表中关联自己ID的字段，  joinColumn是列名，inverseJoinColumns表示中间表中关联对方ID的字段。
    @JoinTable(name = "employee_role",joinColumns = @JoinColumn(name = "employee_id"),
            inverseJoinColumns = @JoinColumn(name = "role_id"))
    @JsonIgnore //生成json是忽略这个属性(数据大多，全部拿到没有意义，还有可能造成死循环)
    //将角色设置进来 有多个角色不能重复
    private Set<Role> roles = new HashSet<>();