>文章首發於公眾號《程式設計師果果》
>地址：https://mp.weixin.qq.com/s/QO5L1-RCR-jmIuHlZIfkqQ

## 簡介
JSON Web Token（縮寫 JWT）是目前最流行的跨域認證解決方案。[JSON Web Token 入門教程 - 阮一峰](http://www.ruanyifeng.com/blog/2018/07/json_web_token-tutorial.html)，這篇文章可以幫你瞭解JWT的概念。本文重點講解Spring Boot 結合 jwt ，來實現前後端分離中，介面的安全呼叫。

## 快速上手
之前的文章已經對 Spring Security 進行了講解，這一節對涉及到 Spring Security 的配置不詳細講解。若不瞭解 Spring Security 先移步到 [Spring Boot Security 詳解](https://mp.weixin.qq.com/s/vxw4EeJ-LWxQtD0xlyB0nA)。

### 建表
```sql
DROP TABLE IF EXISTS `user`;
DROP TABLE IF EXISTS `role`;
DROP TABLE IF EXISTS `user_role`;
DROP TABLE IF EXISTS `role_permission`;
DROP TABLE IF EXISTS `permission`;

CREATE TABLE `user` (
`id` bigint(11) NOT NULL AUTO_INCREMENT,
`username` varchar(255) NOT NULL,
`password` varchar(255) NOT NULL,
PRIMARY KEY (`id`) 
);
CREATE TABLE `role` (
`id` bigint(11) NOT NULL AUTO_INCREMENT,
`name` varchar(255) NOT NULL,
PRIMARY KEY (`id`) 
);
CREATE TABLE `user_role` (
`user_id` bigint(11) NOT NULL,
`role_id` bigint(11) NOT NULL
);
CREATE TABLE `role_permission` (
`role_id` bigint(11) NOT NULL,
`permission_id` bigint(11) NOT NULL
);
CREATE TABLE `permission` (
`id` bigint(11) NOT NULL AUTO_INCREMENT,
`url` varchar(255) NOT NULL,
`name` varchar(255) NOT NULL,
`description` varchar(255) NULL,
`pid` bigint(11) NOT NULL,
PRIMARY KEY (`id`) 
);

INSERT INTO user (id, username, password) VALUES (1,'user','e10adc3949ba59abbe56e057f20f883e'); 
INSERT INTO user (id, username , password) VALUES (2,'admin','e10adc3949ba59abbe56e057f20f883e'); 
INSERT INTO role (id, name) VALUES (1,'USER');
INSERT INTO role (id, name) VALUES (2,'ADMIN');
INSERT INTO permission (id, url, name, pid) VALUES (1,'/user/hi','',0);
INSERT INTO permission (id, url, name, pid) VALUES (2,'/admin/hi','',0);
INSERT INTO user_role (user_id, role_id) VALUES (1, 1);
INSERT INTO user_role (user_id, role_id) VALUES (2, 1);
INSERT INTO user_role (user_id, role_id) VALUES (2, 2);
INSERT INTO role_permission (role_id, permission_id) VALUES (1, 1);
INSERT INTO role_permission (role_id, permission_id) VALUES (2, 1);
INSERT INTO role_permission (role_id, permission_id) VALUES (2, 2);
```

### 關鍵程式碼
#### pom.xml
```xml
<dependency>
    <groupid>org.springframework.boot</groupid>
    <artifactid>spring-boot-starter-web</artifactid>
</dependency>
<dependency>
    <groupid>org.springframework.boot</groupid>
    <artifactid>spring-boot-starter-security</artifactid>
</dependency>
<dependency>
    <groupid>io.jsonwebtoken</groupid>
    <artifactid>jjwt</artifactid>
    <version>0.9.0</version>
</dependency>
<dependency>
    <groupid>mysql</groupid>
    <artifactid>mysql-connector-java</artifactid>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupid>org.mybatis.spring.boot</groupid>
    <artifactid>mybatis-spring-boot-starter</artifactid>
    <version>2.0.0</version>
</dependency>
```

### application.yml
```
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/spring-security-jwt?useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: root

```

### SecurityConfig

```java
@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

@Autowired
    private UserDetailsService userDetailsService;

@Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {

//校驗使用者
        auth.userDetailsService( userDetailsService ).passwordEncoder( new PasswordEncoder() {
            //對密碼進行加密
            @Override
            public String encode(CharSequence charSequence) {
                System.out.println(charSequence.toString());
                return DigestUtils.md5DigestAsHex(charSequence.toString().getBytes());
            }
            //對密碼進行判斷匹配
            @Override
            public boolean matches(CharSequence charSequence, String s) {
                String encode = DigestUtils.md5DigestAsHex(charSequence.toString().getBytes());
                boolean res = s.equals( encode );
                return res;
            }
        } );

}

@Override
    protected void configure(HttpSecurity http) throws Exception {

http.csrf().disable()
                //因為使用JWT，所以不需要HttpSession
                .sessionManagement().sessionCreationPolicy( SessionCreationPolicy.STATELESS).and()
                .authorizeRequests()
                //OPTIONS請求全部放行
                .antMatchers( HttpMethod.OPTIONS, "/**").permitAll()
                //登入介面放行
                .antMatchers("/auth/login").permitAll()
                //其他介面全部接受驗證
                .anyRequest().authenticated();

//使用自定義的 Token過濾器 驗證請求的Token是否合法
        http.addFilterBefore(authenticationTokenFilterBean(), UsernamePasswordAuthenticationFilter.class);
        http.headers().cacheControl();
    }

@Bean
    public JwtTokenFilter authenticationTokenFilterBean() throws Exception {
        return new JwtTokenFilter();
    }

@Bean
    @Override
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }

}
```

### JwtTokenUtil

```java
/**
 * JWT 工具類
 */
@Component
public class JwtTokenUtil implements Serializable {

private static final String CLAIM_KEY_USERNAME = "sub";

/**
     * 5天(毫秒)
     */
    private static final long EXPIRATION_TIME = 432000000;
    /**
     * JWT密碼
     */
    private static final String SECRET = "secret";

/**
     * 簽發JWT
     */
    public String generateToken(UserDetails userDetails) {
        Map<string object=""> claims = new HashMap<>(16);
        claims.put( CLAIM_KEY_USERNAME, userDetails.getUsername() );

return Jwts.builder()
                .setClaims( claims )
                .setExpiration( new Date( Instant.now().toEpochMilli() + EXPIRATION_TIME  ) )
                .signWith( SignatureAlgorithm.HS512, SECRET )
                .compact();
    }

/**
     * 驗證JWT
     */
    public Boolean validateToken(String token, UserDetails userDetails) {
        User user = (User) userDetails;
        String username = getUsernameFromToken( token );

return (username.equals( user.getUsername() ) && !isTokenExpired( token ));
    }

/**
     * 獲取token是否過期
     */
    public Boolean isTokenExpired(String token) {
        Date expiration = getExpirationDateFromToken( token );
        return expiration.before( new Date() );
    }

/**
     * 根據token獲取username
     */
    public String getUsernameFromToken(String token) {
        String username = getClaimsFromToken( token ).getSubject();
        return username;
    }

/**
     * 獲取token的過期時間
     */
    public Date getExpirationDateFromToken(String token) {
        Date expiration = getClaimsFromToken( token ).getExpiration();
        return expiration;
    }

/**
     * 解析JWT
     */
    private Claims getClaimsFromToken(String token) {
        Claims claims = Jwts.parser()
                .setSigningKey( SECRET )
                .parseClaimsJws( token )
                .getBody();
        return claims;
    }

}
```

### JwtTokenFilter
```java
@Component
public class JwtTokenFilter extends OncePerRequestFilter {

@Autowired
    private UserDetailsService userDetailsService;

@Autowired
    private JwtTokenUtil jwtTokenUtil;

/**
     * 存放Token的Header Key
     */
    public static final String HEADER_STRING = "Authorization";

@Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws ServletException, IOException {
        String token = request.getHeader( HEADER_STRING );
        if (null != token) {
            String username = jwtTokenUtil.getUsernameFromToken(token);
            if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
                UserDetails userDetails = this.userDetailsService.loadUserByUsername(username);
                if (jwtTokenUtil.validateToken(token, userDetails)) {
                    UsernamePasswordAuthenticationToken authentication = new UsernamePasswordAuthenticationToken(
                            userDetails, null, userDetails.getAuthorities());
                    authentication.setDetails(new WebAuthenticationDetailsSource().buildDetails(
                            request));
                    SecurityContextHolder.getContext().setAuthentication(authentication);
                }
            }
        }
        chain.doFilter(request, response);
    }
    
}
```

### AuthServiceImpl
```java
@Service
public class AuthServiceImpl implements AuthService {

@Autowired
    private AuthenticationManager authenticationManager;

@Autowired
    private UserDetailsService userDetailsService;

@Autowired
    private JwtTokenUtil jwtTokenUtil;

@Override
    public String login(String username, String password) {
        UsernamePasswordAuthenticationToken upToken = new UsernamePasswordAuthenticationToken( username, password );
        Authentication authentication = authenticationManager.authenticate(upToken);
        SecurityContextHolder.getContext().setAuthentication(authentication);
        UserDetails userDetails = userDetailsService.loadUserByUsername( username );
        String token = jwtTokenUtil.generateToken(userDetails);
        return token;
    }

}
```

關鍵程式碼就是這些，其他類程式碼參照後面提供的原始碼地址。

### 驗證

登入，獲取token

```shell
curl -X POST -d "username=admin&password=123456" http://127.0.0.1:8080/auth/login
```

返回

```shell
eyJhbGciOiJIUzUxMiJ9.eyJzdWIiOiJhZG1pbiIsImV4cCI6MTU1NDQ1MzUwMX0.sglVeqnDGUL9pH1oP3Lh9XrdzJIS42VKBApd2nPJt7e1TKhCEY7AUfIXnzG9vc885_jTq4-h8R6YCtRRJzl8fQ
```

不帶token訪問資源

```shell
curl -X POST -d "name=zhangsan" http://127.0.0.1:8080/admin/hi
```
返回，拒絕訪問

```json
{
    "timestamp": "2019-03-31T08:50:55.894+0000",
    "status": 403,
    "error": "Forbidden",
    "message": "Access Denied",
    "path": "/auth/login"
}
```

攜帶token訪問資源

```shell
curl -X POST -H "Authorization: eyJhbGciOiJIUzUxMiJ9.eyJzdWIiOiJhZG1pbiIsImV4cCI6MTU1NDQ1MzUwMX0.sglVeqnDGUL9pH1oP3Lh9XrdzJIS42VKBApd2nPJt7e1TKhCEY7AUfIXnzG9vc885_jTq4-h8R6YCtRRJzl8fQ" -d "name=zhangsan" http://127.0.0.1:8080/admin/hi
```

返回正確

```
hi zhangsan , you have 'admin' role
```

## 原始碼
https://github.com/gf-huanchupk/SpringBootLearning/tree/master/springboot-jwt</string>

Spring Boot Security 整合 JWT 實現無狀態的分散式API介面

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