mybatis用户角色权限一对多关联查询

mybatis一对多关联查询案例

• 1.需求
• 2.数据库说明
• 3.实体说明
• 4.mybatis SQL语句编写

---

一.需求
在做角色权限管理时，需要根据用户名查询其对应的所有角色以及拥有的所有权限

---

二.数据库说明
数据库有如下几个表

用户表（users）

id,用户名，真是姓名，密码，性别，出生日期，描述，创建日期

角色表(roles)

id,角色描述

权限表(permissions)

id,权限名称，权限资源

---

除了这三张表外，还要两张表来将三者关联起来：

用户角色关联表(users_roles)

用户id、角色id

角色权限关联表(roles_permissions)

用户角色关联表(users_roles)

三.实体说明

1.用户实体说明

用户与角色为多对多的关系，则用户实体中应该包含多个角色，此处用list封装

public class Users {
    private Integer id;
    private String username;
    private String name;
    private List educates; 
    private String password;
    private Byte sex;
    @DateTimeFormat(pattern = "yyyy-MM-dd")//前段到后台注解
    private Date birthday;
    private Date createtime;
    private String content;
    private List rolesList;
    public List getEducates() {
        return educates;
    }

    public void setEducates(List educates) {
        this.educates = educates;
    }
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username == null ? null : username.trim();
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password == null ? null : password.trim();
    }

    public Byte getSex() {
        return sex;
    }

    public void setSex(Byte sex) {
        this.sex = sex;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public Date getCreatetime() {
        return createtime;
    }

    public void setCreatetime(Date createtime) {
        this.createtime = createtime;
    }


    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content == null ? null : content.trim();
    }

    public List getRolesList() {
        return rolesList;
    }

    public void setRolesList(List rolesList) {
        this.rolesList = rolesList;
    }


    public void setName(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return "Users [id=" + id + ", username=" + username + ", name=" + name + ", educates=" + educates
                + ", password=" + password + ", sex=" + sex + ", birthday=" + birthday + ", createtime=" + createtime
                + ", content=" + content + ", rolesList=" + rolesList + "]";
    }
}

2.角色实体说明

角色与权限为多对多的关系，即一个角色对应多个权限，此处用list属性进行权限封装

public class Roles {
    private Integer id;

    private String description;

    private List permissionsList;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description == null ? null : description.trim();
    }

    public List getPermissionsList() {
        return permissionsList;
    }

    public void setPermissionsList(List permissionsList) {
        this.permissionsList = permissionsList;
    }

    @Override
    public String toString() {
        return "Roles [id=" + id + ", description=" + description + ", permissionsList=" + permissionsList + "]";
    }
}

3.权限实体说明

public class Permissions {
    private Integer id;

    private String url;

    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url == null ? null : url.trim();
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    @Override
    public String toString() {
        return "Permissions [id=" + id + ", url=" + url + ", name=" + name + "]";
    }

}

---

• 四.mybatis SQL语句编写

在mapper映射文件中，编写根据用户名查找用户的方法（findUsersByName），将用户对应的角色以及拥有的权限封装

    
    
    



    select id, url,name  from permissions where id in (select roles_permissions.permission_id from roles_permissions where roles_permissions.role_id=#{id})



    select id, description from roles where id in (select users_roles.role_id from users_roles where users_roles.user_id=#{id})



    select id,username,password,sex,birthday,createtime,content from        users where username=#{username}

“`
总结
1.关联查询首先要建立对应的需求实体
2.了解resultmap属性