案例

在前后端分离的，后端微服务的情况下，会话已经不再适合保存在服务端，使用redis可以保存会话，但是需要在redis集群之间进行复制，如果用户较多，保存的数据量也比较大。

JWT实现无状态的会话机制，是一个解决方案。

1、什么是无状态？

微服务集群中的每个服务，对外提供的都使用RESTful风格的接口。而RESTful风格的一个最重要的规范就是：服务的无状态性，即：

1、服务端不保存任何客户端请求者信息
2、客户端的每次请求必须具备自描述信息，通过这些信息识别客户端身份

2、如何实现无状态？

1、首先客户端发送账户名/密码到服务端进行认证
2、认证通过后，服务端将用户信息加密并且编码成一个token，返回给客户端
3、以后客户端每次发送请求，都需要携带认证的token
4、服务端对客户端发送来的token进行解密，判断是否有效，并且获取用户登录信息

3、JWT

JWT 作为一种规范，并没有和某一种语言绑定在一起，常用的Java 实现是GitHub 上的开源项目 jjwt，地址如下：https://github.com/jwtk/jjwt

代码

说明：

1、一个登陆接口/login，用于获取token
2、一个用户接口/hello，用户角色可以访问
3、一个管理接口/admin，管理角色可以访问

1、启动文件

package com.baiziwan.authorize;

import org.mybatis.spring.annotation.MapperScan;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.scheduling.annotation.EnableAsync;

@SpringBootApplication
@EnableDiscoveryClient
@MapperScan({"com.baiziwan.authorize.*.dao", "com.baiziwan.authorize.*.*.dao"})
@EnableAsync
public class AuthorizeApplication {
    private static final Logger LOGGER = LoggerFactory.getLogger(AuthorizeApplication.class);

    public static void main(String[] args) {
        try {
            SpringApplication.run(AuthorizeApplication.class, args);
        } catch (Exception e) {
            LOGGER.error("启动失败！", e);
        }
    }
}

2、pom文件主要依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt</artifactId>
    <version>0.9.1</version>
</dependency>
<dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-oauth3-resource-server</artifactId>
            <version>5.1.3.RELEASE</version>
        </dependency>

3、User文件

package com.baiziwan.authorize.model;

import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.userdetails.UserDetails;

import java.util.Collection;
import java.util.List;

public class User implements UserDetails {
    private String username;
    private String password;
    private List<GrantedAuthority> authorities;

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return authorities;
    }

    @Override
    public String getPassword() {
        return password;
    }

    public String getUsername() {
        return username;
    }
    @Override
    public boolean isAccountNonExpired() {
        return true;
    }
    @Override
    public boolean isAccountNonLocked() {
        return true;
    }
    @Override
    public boolean isCredentialsNonExpired() {
        return true;
    }
    @Override
    public boolean isEnabled() {
        return true;
    }

}

4、控制器url

package com.baiziwan.authorize.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    //需要jwt访问，user角色可以访问
    @GetMapping("/hello")
    public String hello() {
        return "hello jwt !";
    }

    //需要jwt访问，admin角色可以访问
    @GetMapping("/admin")
    public String admin() {
        return "hello admin !";
    }

}

5、JWT 过滤器配置

1、一个是用户登录的过滤器，在用户的登录的过滤器中校验用户是否登录成功，如果登录成功，则生成一个token返回给客户端，登录失败则给前端一个登录失败的提示。
2、第二个过滤器则是当其他请求发送来，校验token的过滤器，如果校验成功，就让请求继续执行。

package com.baiziwan.authorize.filter;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.AuthorityUtils;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.web.filter.GenericFilterBean;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.List;

public class JwtFilter extends GenericFilterBean {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) servletRequest;
        String jwtToken = req.getHeader("authorization");
        System.out.println(jwtToken);
        Claims claims = Jwts.parser().setSigningKey("sang@123").parseClaimsJws(jwtToken.replace("Bearer",""))
                .getBody();
        String username = claims.getSubject();//获取当前登录用户名
        List<GrantedAuthority> authorities = AuthorityUtils.commaSeparatedStringToAuthorityList((String) claims.get("authorities"));
        UsernamePasswordAuthenticationToken token = new UsernamePasswordAuthenticationToken(username, null, authorities);
        SecurityContextHolder.getContext().setAuthentication(token);
        filterChain.doFilter(req,servletResponse);
    }
}

package com.baiziwan.authorize.filter;

import com.baiziwan.authorize.model.User;
import com.fasterxml.jackson.databind.ObjectMapper;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter;
import org.springframework.security.web.util.matcher.AntPathRequestMatcher;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collection;
import java.util.Date;

public class JwtLoginFilter extends AbstractAuthenticationProcessingFilter {

    public JwtLoginFilter(String defaultFilterProcessesUrl, AuthenticationManager authenticationManager) {
        super(new AntPathRequestMatcher(defaultFilterProcessesUrl));
        setAuthenticationManager(authenticationManager);
    }

    @Override
    public Authentication attemptAuthentication(HttpServletRequest req, HttpServletResponse resp) throws AuthenticationException, IOException, ServletException {
        User user = new ObjectMapper().readValue(req.getInputStream(), User.class);
        return getAuthenticationManager().authenticate(new UsernamePasswordAuthenticationToken(user.getUsername(), user.getPassword()));
    }
    @Override
    protected void successfulAuthentication(HttpServletRequest req, HttpServletResponse resp, FilterChain chain, Authentication authResult) throws IOException, ServletException {
        Collection<? extends GrantedAuthority> authorities = authResult.getAuthorities();
        StringBuffer as = new StringBuffer();
        for (GrantedAuthority authority : authorities) {
            as.append(authority.getAuthority())
                    .append(",");
        }
        String jwt = Jwts.builder()
                .claim("authorities", as)//配置用户角色
                .setSubject(authResult.getName())
                .setExpiration(new Date(System.currentTimeMillis() + 10 * 60 * 1000))
                .signWith(SignatureAlgorithm.HS512,"sang@123")
                .compact();
        resp.setContentType("application/json;charset=utf-8");
        PrintWriter out = resp.getWriter();
        out.write(new ObjectMapper().writeValueAsString(jwt));
        out.flush();
        out.close();
    }
    protected void unsuccessfulAuthentication(HttpServletRequest req, HttpServletResponse resp, AuthenticationException failed) throws IOException, ServletException {
        resp.setContentType("application/json;charset=utf-8");
        PrintWriter out = resp.getWriter();
        out.write("登录失败!");
        out.flush();
        out.close();
    }
}

6、Spring Security 配置

1、简单起见，这里并未连接数据库，我直接在内存中配置了两个用户，两个用户具备不同的角色。
2、配置路径规则时， /hello 接口必须要具备 user 角色才能访问， /admin 接口必须要具备 admin 角色才能访问，POST 请求并且是 /login 接口则可以直接通过，其他接口必须认证后才能访问。

package com.baiziwan.authorize.config;

import com.baiziwan.authorize.filter.JwtFilter;
import com.baiziwan.authorize.filter.JwtLoginFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpMethod;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.crypto.password.NoOpPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;

@Configuration
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    @Bean
    PasswordEncoder passwordEncoder() {
        return NoOpPasswordEncoder.getInstance();
    }

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.inMemoryAuthentication().withUser("admin")
                .password("123").roles("admin")
                .and()
                .withUser("sang")
                .password("456")
                .roles("user");
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .antMatchers(HttpMethod.GET,"/.well-known/jwks.json").permitAll()
                .antMatchers("/hello").hasRole("user")
                .antMatchers("/admin").hasRole("admin")
                .antMatchers(HttpMethod.POST, "/login").permitAll()
                .anyRequest().authenticated()
                .and()
                .addFilterBefore(new JwtLoginFilter("/login",authenticationManager()),UsernamePasswordAuthenticationFilter.class)
                .addFilterBefore(new JwtFilter(), UsernamePasswordAuthenticationFilter.class)
                .csrf().disable();
    }
}

7、测试效果

1、获取token

2、带令牌访问