通過重寫loadUserByUsername方法查詢對應用戶的關鍵代碼

package com.tszr.security;

import com.tszr.entity.Authority;
import com.tszr.entity.MyUser;
import com.tszr.repository.MyUserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.List;

@Service
public class MyUserSecurityService implements UserDetailsService {
    @Autowired
    private MyUserRepository myUserRepository;

    /**
     * 通過重寫loadUserByUsername方法查詢對應的用戶
     * UserDetails是Spring Security的一個核心接口
     * UserDetails定義了可以獲取用戶名、密碼、權限等與認證相關信息的方法
     */
    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        //根據用戶名（頁面接收的用戶名）查詢當前用戶
        MyUser myUser = myUserRepository.findByUsername(username);
        if(myUser == null) {
            throw new UsernameNotFoundException("用戶名不存在");
        }
        //GrantedAuthority代表賦予當前用戶的權限（認證權限）
        List<GrantedAuthority> authorities = new ArrayList<GrantedAuthority>();
        //獲得當前用戶權限集合
        List<Authority> roles = myUser.getAuthorityList();

        //將當前用戶的權限保存為用戶的認證權限
        for (Authority authority : roles) {
            GrantedAuthority sg = new SimpleGrantedAuthority(authority.getName());
            authorities.add(sg);
        }
        //org.springframework.security.core.userdetails.User是Spring Security的內部實現，
        //專門用於保存用戶名、密碼、權限等與認證相關的信息
        User su = new User(myUser.getUsername(), myUser.getPassword(), authorities);
        return su;
    }
}