如图，是一种通用的用户权限模型。一般情况下会有5张表，分别是：用户表，角色表，权限表，用户角色关系表，角色权限对应表。一般，资源分配时是基于角色的（即，资源访问权限赋给角色，用户通过角色进而拥有权限）；而访问资源的时候是基于资源权限去进行授权判断的。Spring Security和Apache Shiro是两个应用比较多的权限管理框架。Spring Security依赖Spring，其功能强大，相对于Shiro而言学习难度稍大一些。Spring的强大是不言而喻的，可扩展性也很强，强大到用Spring家族的产品只要按照其推荐的做法来就非常非常简单，否则，自己去整合过程可能会很痛苦。目前，我们项目是基于Spring Boot的，而且Spring Boot的权限管理也是推荐使用Spring Security的，所以再难也是要学习的。

Spring Security简介

Spring Security致力于为Java应用提供认证和授权管理。它是一个强大的，高度自定义的认证和访问控制框架。具体介绍参见https://docs.spring.io/spring-security/site/docs/5.0.5.RELEASE/reference/htmlsingle/这句话包括两个关键词：Authentication（认证）和Authorization（授权，也叫访问控制）认证是验证用户身份的合法性，而授权是控制你可以做什么。简单地来说，认证就是你是谁，授权就是你可以做什么。在开始集成之前，我们先简单了解几个接口：

AuthenticationProvider

AuthenticationProvider接口是用于认证的，可以通过实现这个接口来定制我们自己的认证逻辑，它的实现类有很多，默认的是JaasAuthenticationProvider它的全称是 Java Authentication and Authorization Service (JAAS)

AccessDecisionManager

AccessDecisionManager是用于访问控制的，它决定用户是否可以访问某个资源，实现这个接口可以定制我们自己的授权逻辑。

AccessDecisionVoter

AccessDecisionVoter是投票器，在授权的时通过投票的方式来决定用户是否可以访问，这里涉及到投票规则。

UserDetailsService

UserDetailsService是用于加载特定用户信息的，它只有一个接口通过指定的用户名去查询用户。

UserDetails

UserDetails代表用户信息，即主体，相当于Shiro中的Subject。User是它的一个实现。

Spring Boot集成Spring Security

按照官方文档的说法，为了定义我们自己的认证管理，我们可以添加UserDetailsService, AuthenticationProvider, or AuthenticationManager这种类型的Bean。实现的方式有多种，这里我选择最简单的一种（因为本身我们这里的认证授权也比较简单）通过定义自己的UserDetailsService从数据库查询用户信息，至于认证的话就用默认的。

Maven依赖

 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>com.cjs.example</groupId>
     <artifactId>cjs-springsecurity-example</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>
 
     <name>cjs-springsecurity-example</name>
     <description></description>
 
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>2.0.2.RELEASE</version>
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <java.version>1.8</java.version>
     </properties>
 
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-cache</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-redis</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-security</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-thymeleaf</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
         <dependency>
             <groupId>org.thymeleaf.extras</groupId>
             <artifactId>thymeleaf-extras-springsecurity4</artifactId>
             <version>3.0.2.RELEASE</version>
         </dependency>
 
 
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.springframework.security</groupId>
             <artifactId>spring-security-test</artifactId>
             <scope>test</scope>
         </dependency>
     </dependencies>
 
     <build>
         <plugins>
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
             </plugin>
         </plugins>
     </build>
 
 </project>

Security配置

 package com.cjs.example.config;
 
 import com.cjs.example.support.MyUserDetailsService;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
 import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
 import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
 import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
 import org.springframework.security.crypto.password.PasswordEncoder;
 
 @Configuration
 @EnableWebSecurity
 @EnableGlobalMethodSecurity(prePostEnabled = true)  //  启用方法级别的权限认证
 public class SecurityConfig extends WebSecurityConfigurerAdapter {
 
     @Autowired
     private MyUserDetailsService myUserDetailsService;
 
 
     @Override
     protected void configure(HttpSecurity http) throws Exception {
         //  允许所有用户访问"/"和"/index.html"
         http.authorizeRequests()
                 .antMatchers("/", "/index.html").permitAll()
                 .anyRequest().authenticated()   // 其他地址的访问均需验证权限
                 .and()
                 .formLogin()
                 .loginPage("/login.html")   //  登录页
                 .failureUrl("/login-error.html").permitAll()
                 .and()
                 .logout()
                 .logoutSuccessUrl("/index.html");
     }
 
     @Override
     protected void configure(AuthenticationManagerBuilder auth) throws Exception {
         auth.userDetailsService(myUserDetailsService).passwordEncoder(passwordEncoder());
     }
 
     @Bean
     public PasswordEncoder passwordEncoder() {
         return new BCryptPasswordEncoder();
     }
 
 }

MyUserDetailsService

 package com.cjs.example.support;
 
 import com.cjs.example.entity.SysPermission;
 import com.cjs.example.entity.SysRole;
 import com.cjs.example.entity.SysUser;
 import com.cjs.example.service.UserService;
 import org.springframework.beans.factory.annotation.Autowired;
 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 MyUserDetailsService implements UserDetailsService {
 
     @Autowired
     private UserService userService;
 
     /**
      * 授权的时候是对角色授权，而认证的时候应该基于资源，而不是角色，因为资源是不变的，而用户的角色是会变的
      */
 
     @Override
     public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
         SysUser sysUser = userService.getUserByName(username);
         if (null == sysUser) {
             throw new UsernameNotFoundException(username);
         }
         List<SimpleGrantedAuthority> authorities = new ArrayList<>();
         for (SysRole role : sysUser.getRoleList()) {
             for (SysPermission permission : role.getPermissionList()) {
                 authorities.add(new SimpleGrantedAuthority(permission.getCode()));
             }
         }
 
         return new User(sysUser.getUsername(), sysUser.getPassword(), authorities);
     }
 }

权限分配

 package com.cjs.example.service.impl;
 
 import com.cjs.example.dao.UserDao;
 import com.cjs.example.entity.SysUser;
 import com.cjs.example.service.UserService;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.cache.annotation.Cacheable;
 import org.springframework.stereotype.Service;
 
 @Service
 public class UserServiceImpl implements UserService {
 
     @Autowired
     private UserDao userDao;
 
     @Cacheable(cacheNames = "authority", key = "#username")
     @Override
     public SysUser getUserByName(String username) {
         return userDao.selectByName(username);
     }
 }

 package com.cjs.example.dao;
 
 import com.cjs.example.entity.SysPermission;
 import com.cjs.example.entity.SysRole;
 import com.cjs.example.entity.SysUser;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Repository;
 
 import java.util.Arrays;
 
 @Slf4j
 @Repository
 public class UserDao {
 
     private SysRole admin = new SysRole("ADMIN", "管理员");
     private SysRole developer = new SysRole("DEVELOPER", "开发者");
 
     {
         SysPermission p1 = new SysPermission();
         p1.setCode("UserIndex");
         p1.setName("个人中心");
         p1.setUrl("/user/index.html");
 
         SysPermission p2 = new SysPermission();
         p2.setCode("BookList");
         p2.setName("图书列表");
         p2.setUrl("/book/list");
 
         SysPermission p3 = new SysPermission();
         p3.setCode("BookAdd");
         p3.setName("添加图书");
         p3.setUrl("/book/add");
 
         SysPermission p4 = new SysPermission();
         p4.setCode("BookDetail");
         p4.setName("查看图书");
         p4.setUrl("/book/detail");
 
         admin.setPermissionList(Arrays.asList(p1, p2, p3, p4));
         developer.setPermissionList(Arrays.asList(p1, p2));
 
     }
 
     public SysUser selectByName(String username) {
         log.info("从数据库中查询用户");
         if ("zhangsan".equals(username)) {
             SysUser sysUser = new SysUser("zhangsan", "$2a$10$EIfFrWGINQzP.tmtdLd2hurtowwsIEQaPFR9iffw2uSKCOutHnQEm");
             sysUser.setRoleList(Arrays.asList(admin, developer));
             return sysUser;
         }else if ("lisi".equals(username)) {
             SysUser sysUser = new SysUser("lisi", "$2a$10$EIfFrWGINQzP.tmtdLd2hurtowwsIEQaPFR9iffw2uSKCOutHnQEm");
             sysUser.setRoleList(Arrays.asList(developer));
             return sysUser;
         }
         return null;
     }
 
 }

示例

这里我设计的例子是用户登录成功以后跳到个人中心，然后用户可以可以进入图书列表查看。用户zhangsan可以查看所有的，而lisi只能查看图书列表，不能添加不能查看详情。

页面设计

LoginController.java

 package com.cjs.example.controller;
 
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.RequestMapping;
 
 @Controller
 public class LoginController {
 
     // Login form
     @RequestMapping("/login.html")
     public String login() {
         return "login.html";
     }
 
     // Login form with error
     @RequestMapping("/login-error.html")
     public String loginError(Model model) {
         model.addAttribute("loginError", true);
         return "login.html";
     }
 
 }

BookController.java

 package com.cjs.example.controller;
 
 import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 
 @Controller
 @RequestMapping("/book")
 public class BookController {
 
     @PreAuthorize("hasAuthority('BookList')")
     @GetMapping("/list.html")
     public String list() {
         return "book/list";
     }
 
     @PreAuthorize("hasAuthority('BookAdd')")
     @GetMapping("/add.html")
     public String add() {
         return "book/add";
     }
 
     @PreAuthorize("hasAuthority('BookDetail')")
     @GetMapping("/detail.html")
     public String detail() {
         return "book/detail";
     }
 }

UserController.java

 package com.cjs.example.controller;
 
 import com.cjs.example.entity.SysUser;
 import com.cjs.example.service.UserService;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.ResponseBody;
 
 @Controller
 @RequestMapping("/user")
 public class UserController {
 
     @Autowired
     private UserService userService;
 
     /**
      * 个人中心
      */
     @PreAuthorize("hasAuthority('UserIndex')")
     @GetMapping("/index")
     public String index() {
         return "user/index";
     }
 
     @RequestMapping("/hi")
     @ResponseBody
     public String hi() {
         SysUser sysUser = userService.getUserByName("zhangsan");
         return sysUser.toString();
     }
 
 }

index.html

 <!DOCTYPE html>
 <html lang="en">
 <head>
     <meta charset="UTF-8">
     <title>首页</title>
 </head>
 <body>
     <h2>这里是首页</h2>
 </body>
 </html>

login.html

 <!DOCTYPE html>
 <html lang="zh" xmlns:th="http://www.thymeleaf.org">
 <head>
     <meta charset="UTF-8">
     <title>Login page</title>
 </head>
 <body>
 <h1>Login page</h1>
 <p th:if="${loginError}" class="error">用户名或密码错误</p>
 <form th:action="@{/login.html}" method="post">
     <label for="username">Username</label>:
     <input type="text" id="username" name="username" autofocus="autofocus" /> 

     <label for="password">Password</label>:
     <input type="password" id="password" name="password" /> 

     <input type="submit" value="Login" />
 </form>
 </body>
 </html>

/user/index.html

 <!DOCTYPE html>
 <html lang="zh" xmlns:th="http://www.thymeleaf.org">
 <head>
     <meta charset="UTF-8">
     <title>个人中心</title>
 </head>
 <body>
     <h2>个人中心</h2>
     <div th:insert="~{fragments/header::logout}"></div>
     <a href="/book/list.html">图书列表</a>
 </body>
 </html>

/book/list.html

<!DOCTYPE html>
<html lang="zh" xmlns:th="http://www.thymeleaf.org" xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity4">
<head>
    <meta charset="UTF-8">
    <title>图书列表</title>
</head>
<body>
<div th:insert="~{fragments/header::logout}"></div>
<h2>图书列表</h2>
<div sec:authorize="hasAuthority('BookAdd')">
    <button onclick="">添加</button>
</div>
<table border="1" cellspacing="0" style="width: 20%">
    <thead>
        <tr>
            <th>名称</th>
            <th>出版社</th>
            <th>价格</th>
            <th>操作</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Java从入门到放弃</td>
            <td>机械工业出版社</td>
            <td>39</td>
            <td><span sec:authorize="hasAuthority('BookDetail')"><a href="/book/detail.html">查看</a></span></td>
        </tr>
        <tr>
            <td>MySQ从删库到跑路</td>
            <td>清华大学出版社</td>
            <td>59</td>
            <td><span sec:authorize="hasAuthority('BookDetail')"><a href="/book/detail.html">查看</a></span></td>
        </tr>
    </tbody>
</table>
</body>
</html>

header.html

 <!DOCTYPE html>
 <html xmlns:th="http://www.thymeleaf.org" xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity4">
 <body>
 <div th:fragment="logout" class="logout" sec:authorize="isAuthenticated()">
     Logged in user: <span sec:authentication="name"></span> |
     Roles: <span sec:authentication="principal.authorities"></span>
     <div>
         <form action="#" th:action="@{/logout}" method="post">
             <input type="submit" value="退出" />
         </form>
     </div>
 </div>
 </body>
 </html>

错误处理

ErrorController.java

 package com.cjs.example.controller;
 
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.http.HttpStatus;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.ResponseStatus;
 
 @Slf4j
 @ControllerAdvice
 public class ErrorController {
 
     @ExceptionHandler(Throwable.class)
     @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
     public String exception(final Throwable throwable, final Model model) {
         log.error("Exception during execution of SpringSecurity application", throwable);
         String errorMessage = (throwable != null ? throwable.getMessage() : "Unknown error");
         model.addAttribute("errorMessage", errorMessage);
         return "error";
     }
 
 }

error.html

 <!DOCTYPE html>
 <html xmlns:th="http://www.thymeleaf.org">
 <head>
     <title>Error page</title>
     <meta charset="utf-8" />
 </head>
 <body th:with="httpStatus=${T(org.springframework.http.HttpStatus).valueOf(#response.status)}">
 <h1 th:text="|${httpStatus} - ${httpStatus.reasonPhrase}|">404</h1>
 <p th:utext="${errorMessage}">Error java.lang.NullPointerException</p>
 <a href="index.html" th:href="@{/index.html}">返回首页</a>
 </body>
 </html>

效果演示

zhangsan登录

lisi登录

至此，可以实现基本的权限管理

工程结构

代码已上传至https://github.com/chengjiansheng/cjs-springsecurity-example.git

访问控制表达式

其它

通常情况下登录成功或者失败以后不是跳转到页面而是返回json数据，该怎么做呢？

可以继承SavedRequestAwareAuthenticationSuccessHandler，并在配置中指定successHandler或者继承SimpleUrlAuthenticationFailureHandler，并在配置中指定failureHandler

 package com.cjs.example.handler;
 
 import org.springframework.security.core.Authentication;
 import org.springframework.security.web.authentication.SavedRequestAwareAuthenticationSuccessHandler;
 
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.util.HashMap;
 
 public class MySavedRequestAwareAuthenticationSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler {
     @Override
     public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws ServletException, IOException {
 
 //        // Use the DefaultSavedRequest URL
 //        String targetUrl = savedRequest.getRedirectUrl();
 //        logger.debug("Redirecting to DefaultSavedRequest Url: " + targetUrl);
 //        getRedirectStrategy().sendRedirect(request, response, targetUrl);
 
         Map<String, Object> map = new HashMap<>();
         response.getWriter().write(JSON.toJSONString(map));
 
 
     }
 }

这么复杂感觉还不如自己写个Filter还简单些

是的，仅仅是这些的话还真不如自己写个过滤器来得简单，但是Spring Security的功能远不止如此，比如OAuth2，CSRF等等

这个只适用单应用，不可能每个需要权限的系统都这么去写，可以不可以做成认证中心，做单点登录？

当然是可以的，而且必须可以。权限分配可以用一个管理后台，认证和授权必须独立出来，下一节用OAuth2.0来实现

参考

https://docs.spring.io/spring-security/site/docs/5.0.5.RELEASE/reference/htmlsingle/#el-pre-post-annotationshttps://docs.spring.io/spring-security/site/docs/5.0.5.RELEASE/reference/htmlsingle/#getting-startedhttps://www.thymeleaf.org/doc/articles/standarddialect5minutes.htmlhttps://www.thymeleaf.org/doc/articles/layouts.htmlhttps://www.thymeleaf.org/doc/articles/springsecurity.htmlhttps://blog.csdn.net/u283056051/article/details/55803855https://segmentfault.com/a/1190000008893479https://www.bbsmax.com/A/A2dmY2DWde/https://blog.csdn.net/qq_29580525/article/details/79317969