多对多映射（java的引用）

class User{
    private String userid;
    private String name;
    private String password;
    private Role role;
    public User(String userid,String name,String password){
        this.userid = userid;
        this.name = name;
        this.password = password;
    }
    public void setRole(Role role){
        this.role = role;
    }
    public Role getRole(){
        return role;
    }
    public String getInfo(){
        return "用户id"+this.userid+"用户名"+this.name+"密码"+this.password;
    }
}
class Role{
    private int rid;
    private String title;
    private User users[];
    private Group groups[];
    public Role(int rid,String title){
        this.rid = rid;
        this.title = title;
    }
    public void setUser(User users[]){
        this.users = users;
    }

    public void setGroups(Group[] groups) {
        this.groups = groups;
    }

    public User[] getUser(){
        return users;
    }

    public Group[] getGroups() {
        return this.groups;
    }

    public String getInfo(){
        return "角色id"+this.rid+"角色名"+this.title;
    }
}
class Group{
    private int gid;
    private String title;
    private Action actions[];
    private Role roles[];
    public Group(int gid,String title){
        this.gid = gid;
        this.title = title;
    }
    public void setActions(Action actions[]){
        this.actions = actions;
    }

    public void setRoles(Role[] roles) {
        this.roles = roles;
    }

    public Action[] getActions() {
        return this.actions;
    }

    public Role[] getRoles() {
        return this.roles;
    }

    public String getInfo(){
        return "权限组id"+this.gid+"权限组名"+this.title;
    }
}
class Action{
    private int aid;
    private String title;
    private String url;
    private Group group;
    public Action(int aid,String title,String url){
        this.aid = aid;
        this.title = title;
        this.url = url;
    }

    public void setGroup(Group group) {
        this.group = group;
    }

    public Group getGroup() {
        return this.group;
    }

    public String getInfo(){
        return "权限id"+this.aid+"权限名"+this.title+"权限路径"+this.url;
    }
}
public class JavaDemo {
    public static void main(String[] args){
        //第一步：根据表结构设置关系
        //1.定义单独的类对象
        User ua = new User("user-a","用户a","hello");
        User ub = new User("user-b","用户b","hello");
        User uc = new User("user-c","用户c","hello");
        //2.定义权限
        Action act1 = new Action(1,"新闻管理","http://");
        Action act2 = new Action(2,"用户管理","http://");
        Action act3 = new Action(3,"备份管理","http://");
        Action act4 = new Action(4,"缓存管理","http://");
        //3.定义权限组信息
        Group g1 = new Group(1,"管理员");
        Group g2 = new Group(1,"信息管理员");
        //4.定义角色信息
        Role r1 = new Role(10,"超级管理员角色");
        Role r2 = new Role(20,"信息管理员角色");
        //5 设置权限组与权限的关系，一对多关系
        act1.setGroup(g1);//权限与权限组的关系
        act2.setGroup(g1);
        act3.setGroup(g2);
        act4.setGroup(g2);
        g1.setActions(new Action[]{act1,act2});
        g2.setActions(new Action[]{act3,act4});
        //6.权限组与角色关系
        r1.setGroups(new Group[]{g1,g2});
        r2.setGroups(new Group[]{g2});
        g1.setRoles(new Role[]{r1});
        g2.setRoles(new Role[]{r1,r2});
        //7.定义用户与角色的关系
        ua.setRole(r1);
        ub.setRole(r1);
        ub.setRole(r2);
        r1.setUser(new User[]{ua,ub});
        r2.setUser(new User[]{ub});

        System.out.println(ua.getInfo());
        System.out.println("\t[角色]"+ua.getRole().getInfo());

        //一个权限可以输出具备此权限的角色
        System.out.println(act1.getInfo());
        for (int x =0;x<act1.getGroup().getRoles().length;x++){
            System.out.println("\t\t-【角色】"+act1.getGroup().getRoles()[x].getInfo());
            for (int y=0;y<act1.getGroup().getRoles()[x].getUser().length;y++){
                System.out.println("\t\t\t-【用户】"+act1.getGroup().getRoles()[x].getUser()[y].getInfo());
            }
        }
    }
}