Shrio使用Jwt达到前后端分离

概述

前后端分离之后，因为HTTP本身是无状态的，Session就没法用了。项目采用jwt的方案后，请求的主要流程如下：用户登录成功之后，服务端会创建一个jwt的token（jwt的这个token中记录了当前的操作账号），并将这个token返回给前端，前端每次请求服务端的数据时，都会将令牌放入Header或者Parameter中，服务端接收到请求后，会先被拦截器拦截，token检验的拦截器会获取请求中的token，然后会检验token的有效性，拦截器都检验成功后，请求会成功到达实际的业务流程中，执行业务逻辑返回给前端数据。在这个过程中，主要涉及到Shiro的拦截器链，Jwt的token管理，多Realm配置等。

Shiro的Filter链

Shiro的认证和授权都离不开Filter，因此需要对Shiro的Filter的运行流程很清楚，才能自定义Filter来满足企业的实际需要。另外Shiro的Filter虽然原理都和Servlet的Filter相似，甚至都最终继承相同的接口，但是实际还是有些差别。Shiro中的Filter主要是在ShiroFilter内，对指定匹配的URL进行拦截处理，它有自己的Filter链；而Servlet的Filter和ShiroFilter是同一个级别的，即先走Shiro自己的Filter体系，然后才会委托给Servlet容器的FilterChain进行Servlet容器级别的Filter链执行

分析Shiro的默认Filter

在Shiro和Spring Boot整合过程中，需要配置ShiroFilterFactoryBean，该类是ShiroFilter的工厂类，并继承了FactoryBean接口。可以从该接口的方法来分析。该接口getObject获取一个实例，按照逻辑，发现调用createFilterChainManager，并创建默认的Filter(按照命名猜测Map<String, Filter> defaultFilters = manager.getFilters())。

public class ShiroFilterFactoryBean implements FactoryBean, BeanPostProcessor {
    private Map<String, Filter> filters;

    private Map<String, String> filterChainDefinitionMap; 

    /**
     *
     * 该工厂类生产的产品类
     */
    public Object getObject() throws Exception {
        if (instance == null) {
            instance = createInstance();
        }
        return instance;
    }

    protected FilterChainManager createFilterChainManager() {
		//创建默认Filter
        DefaultFilterChainManager manager = new DefaultFilterChainManager();
        Map<String, Filter> defaultFilters = manager.getFilters();
        for (Filter filter : defaultFilters.values()) {
            applyGlobalPropertiesIfNecessary(filter);
        }

        Map<String, Filter> filters = getFilters();
        if (!CollectionUtils.isEmpty(filters)) {
            for (Map.Entry<String, Filter> entry : filters.entrySet()) {
                String name = entry.getKey();
                Filter filter = entry.getValue();
                applyGlobalPropertiesIfNecessary(filter);
                if (filter instanceof Nameable) {
                    ((Nameable) filter).setName(name);
                }
                manager.addFilter(name, filter, false);
            }
        }

        Map<String, String> chains = getFilterChainDefinitionMap();
        if (!CollectionUtils.isEmpty(chains)) {
            for (Map.Entry<String, String> entry : chains.entrySet()) {
                String url = entry.getKey();
                String chainDefinition = entry.getValue();
                manager.createChain(url, chainDefinition);
            }
        }

        return manager;
    }

    protected AbstractShiroFilter createInstance() throws Exception {

        log.debug("Creating Shiro Filter instance.");

        SecurityManager securityManager = getSecurityManager();
        if (securityManager == null) {
            String msg = "SecurityManager property must be set.";
            throw new BeanInitializationException(msg);
        }

        if (!(securityManager instanceof WebSecurityManager)) {
            String msg = "The security manager does not implement the WebSecurityManager interface.";
            throw new BeanInitializationException(msg);
        }
		//创建FilterChainManager
        FilterChainManager manager = createFilterChainManager();

        PathMatchingFilterChainResolver chainResolver = new PathMatchingFilterChainResolver();
        chainResolver.setFilterChainManager(manager);

        return new SpringShiroFilter((WebSecurityManager) securityManager, chainResolver);
    }
    
   ...
}

在DefaultFilterChainManager中addDefaultFilters来添加默认的Filter，DefaultFilter为一系列默认Filter的枚举类。

public class DefaultFilterChainManager implements FilterChainManager {
    
    public Map<String, Filter> getFilters() {
        return filters;
    }

    protected void addFilter(String name, Filter filter, boolean init, boolean overwrite) {
        Filter existing = getFilter(name);
        if (existing == null || overwrite) {
            if (filter instanceof Nameable) {
                ((Nameable) filter).setName(name);
            }
            if (init) {
                initFilter(filter);
            }
            this.filters.put(name, filter);
        }
    }

     /**
     *
     * 创建默认的Filter
     */
    protected void addDefaultFilters(boolean init) {
        for (DefaultFilter defaultFilter : DefaultFilter.values()) {
            addFilter(defaultFilter.name(), defaultFilter.newInstance(), init, false);
        }
    }
    ...
}

从这个枚举类中可以看到之前添加的共有11个默认Filter，它们的名字分别是anon,authc,authcBaisc等。

public enum DefaultFilter {

    anon(AnonymousFilter.class),
    authc(FormAuthenticationFilter.class),
    authcBasic(BasicHttpAuthenticationFilter.class),
    logout(LogoutFilter.class),
    noSessionCreation(NoSessionCreationFilter.class),
    perms(PermissionsAuthorizationFilter.class),
    port(PortFilter.class),
    rest(HttpMethodPermissionFilter.class),
    roles(RolesAuthorizationFilter.class),
    ssl(SslFilter.class),
    user(UserFilter.class);

    private final Class<? extends Filter> filterClass;

    private DefaultFilter(Class<? extends Filter> filterClass) {
        this.filterClass = filterClass;
    }

    public Filter newInstance() {
        return (Filter) ClassUtils.newInstance(this.filterClass);
    }

    public Class<? extends Filter> getFilterClass() {
        return this.filterClass;
    }
	...
}

Filter的继承体系分析

• NameableFilter给Filter起个名字，如果没有设置，默认名字就是FilterName。

• OncePerRequestFilter用于防止多次执行Filter；也就是说一次请求只会走一次拦截器链；另外提供 enabled 属性，表示是否开启该拦截器实例，默认 enabled=true 表示开启，如果不想让某个拦截器工作，可以设置为 false 即可。

• AdviceFilter提供了AOP风格的支持。preHandler：在拦截器链执行之前执行，如果返回true则继续拦截器链；否则中断后续的拦截器链的执行直接返回；可以进行预处理（如身份验证、授权等行为）。postHandle：在拦截器链执行完成后执行，后置处理（如记录执行时间之类的）。afterCompletion：类似于AOP中的后置最终增强；即不管有没有异常都会执行，可以进行清理资源（如接触 Subject 与线程的绑定之类的）。

• PathMatchingFilter内置了pathMatcher的实例，方便对请求路径匹配功能及拦截器参数解析的功能，如下所示，对匹配的路径执行isFilterChainContinued的逻辑，如果都没配到，则直接交给拦截器链。

protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {

    if (this.appliedPaths == null || this.appliedPaths.isEmpty()) {
        if (log.isTraceEnabled()) {
            log.trace("appliedPaths property is null or empty.  This Filter will passthrough immediately.");
        }
        return true;
    }

    for (String path : this.appliedPaths.keySet()) {
        //对匹配路径进行处理
        if (pathsMatch(path, request)) {
            log.trace("Current requestURI matches pattern '{}'.  Determining filter chain execution...", path);
            Object config = this.appliedPaths.get(path);
            return isFilterChainContinued(request, response, path, config);
        }
    }

    return true;
}

• AccessControlFilter提供了访问控制的基础功能，isAccessAllowed访问通过，则交给拦截器链，不通过则执行onAccessDenied来确定交给拦截器还是自己处理

 public boolean onPreHandle(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
        return isAccessAllowed(request, response, mappedValue) || onAccessDenied(request, response, mappedValue);
    }

• AuthenticationFilter认证Filter的基类，一般在isAccessAllowed中执行认证逻辑，另外该Filter提供登录成功后跳转的功能

protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object 		mappedValue) {
    Subject subject = getSubject(request, response);
    return subject.isAuthenticated();
}


protected void issueSuccessRedirect(ServletRequest request, ServletResponse response) throws 		Exception {
    WebUtils.redirectToSavedRequest(request, response, getSuccessUrl());
}

• AuthenticatingFilter是AuthenticationFilter的子类，提供了executeLogin通用逻辑，通常由子类来实现protected abstract AuthenticationToken createToken(ServletRequest request, ServletResponse response)该方法，然后执行subject.login(token)

public abstract class AuthenticatingFilter extends AuthenticationFilter {
    public static final String PERMISSIVE = "permissive";

    protected boolean executeLogin(ServletRequest request, ServletResponse response) throws Exception {
        AuthenticationToken token = createToken(request, response);
        if (token == null) {
            String msg = "createToken method implementation returned null. A valid non-null AuthenticationToken " +
                "must be created in order to execute a login attempt.";
            throw new IllegalStateException(msg);
        }
        try {
            Subject subject = getSubject(request, response);
            subject.login(token);
            return onLoginSuccess(token, subject, request, response);
        } catch (AuthenticationException e) {
            return onLoginFailure(token, e, request, response);
        }
    }

    protected abstract AuthenticationToken createToken(ServletRequest request, ServletResponse response) throws Exception;

    protected AuthenticationToken createToken(String username, String password,
                                              ServletRequest request, ServletResponse response) {
        boolean rememberMe = isRememberMe(request);
        String host = getHost(request);
        return createToken(username, password, rememberMe, host);
    }

    protected AuthenticationToken createToken(String username, String password,
                                              boolean rememberMe, String host) {
        return new UsernamePasswordToken(username, password, rememberMe, host);
    }

    protected boolean onLoginSuccess(AuthenticationToken token, Subject subject,
                                     ServletRequest request, ServletResponse response) throws Exception {
        return true;
    }

    protected boolean onLoginFailure(AuthenticationToken token, AuthenticationException e,
                                     ServletRequest request, ServletResponse response) {
        return false;
    }

    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        return super.isAccessAllowed(request, response, mappedValue) ||
            (!isLoginRequest(request, response) && isPermissive(mappedValue));
    }
    ...
}

在Shiro中添加自定义的Filter

从上面源码分析，知道了Shiro会提供11个默认的Filter，也是按照拦截器模式交由FilterChainManager来管理Filter，并最终返回SpringShiroFilter。所以添加自定义的Filter，主要有三步。

• 实现自己的Filter

如下实现了自己的JwtFilter，主要逻辑可以参考FormAuthenticationFilter。JwtFilter主要是对前端的Api进行校验，检验失败，则抛出异常信息，不给拦截器链处理。

@Slf4j
public class JwtFilter extends AuthenticatingFilter {	
	private static final String TOKEN_NAME = "token";
	
	/**
	 * 创建令牌
	 */
    @Override
    protected AuthenticationToken createToken(ServletRequest servletRequest, ServletResponse servletResponse) throws Exception {
		final String token = getToken((HttpServletRequest) servletRequest);  	
		if(StringUtils.isEmpty(token)) {
			return null;
		}   	
		return new JwtToken(token);   	
    }
    
    /**
     * 获取令牌
     * @param httpServletRequest
     * @return
     */
    private String getToken(HttpServletRequest httpServletRequest) {
    	String token = httpServletRequest.getHeader(TOKEN_NAME);
    	if(StringUtils.isEmpty(token)) {
    		token = httpServletRequest.getParameter(TOKEN_NAME);
    	};
    	if(StringUtils.isEmpty(token)) {
    		Cookie[] cookies = httpServletRequest.getCookies();
    		if(ArrayUtils.isNotEmpty(cookies)) {
    			for(Cookie cookie :cookies) {
    				if(TOKEN_NAME.equals(cookie.getName())) {
    					token = cookie.getValue();
    					break;
    				}
    			}
    		}
    	};	
    	return token;
    }
 
    /**
     * 未通过处理
     * @param servletRequest
     * @param servletResponse
     * @return
     * @throws Exception
     */
    @Override
    protected boolean onAccessDenied(ServletRequest servletRequest, ServletResponse servletResponse) throws Exception {
    	return executeLogin(servletRequest, servletResponse);
    }

    /**
     * 登录失败执行方法
     * @param token
     * @param e
     * @param request
     * @param response
     * @return
     */
	protected boolean onLoginFailure(AuthenticationToken token, AuthenticationException e, ServletRequest request,
			ServletResponse response) {
		response.setContentType("text/html;charset=UTF-8");
		try(OutputStream outputStream = response.getOutputStream()){
			outputStream.write(e.getMessage().getBytes(SystemConsts.CHARSET));
			outputStream.flush();			
		} catch (IOException e1) {
			e1.printStackTrace();
		}	
		return false;
	}
    ...
}

• 将Filter添加到Shiro中

将自定义的Filter添加到Shiro，并要指定的匹配路径。

public ShiroFilterFactoryBean getShiroFilterFactoryBean(@Autowired 			org.apache.shiro.mgt.SecurityManager securityManager, @Autowired JwtFilter jwtFilter) {
		ShiroFilterFactoryBean shiroFilterFactoryBean = new ShiroFilterFactoryBean();

		Map<String, Filter> filterMap = new LinkedHashMap<>();
		filterMap.put("jwt", jwtFilter);
		shiroFilterFactoryBean.setFilters(filterMap);
	
		Map<String, String> filterChainDefinitionMap = new LinkedHashMap<>();
		filterChainDefinitionMap.put("/**", "jwt");	
		shiroFilterFactoryBean.setFilterChainDefinitionMap(filterChainDefinitionMap);
    ...
		return shiroFilterFactoryBean;
	}

注意：SpringBoot自动帮我们注册了我们的Filter(Filter是注册到整个Filter链，而不是Shiro的Filter链)，但是在Shiro中，我们需要自己实现注册，但是又需要Filter实例存在于Spring容器中，以便能使用其他众多服务(自动注入其他组件……)。所以需要取消Spring Boot的自动注入Filter。可以采用如下方式：

@Bean
public FilterRegistrationBean registration(@Qualifier("devCryptoFilter") DevCryptoFilter filter）{
    FilterRegistrationBean registration = new FilterRegistrationBean(filter);
    registration.setEnabled(false);
    return registration;
}

Jwt整合

使用Jwt需要我们提供对token的创建，校验和获取token中信息的方法。网上有很多，可以借鉴，而且token中也可以存一些其他数据。

public class JwtUtil {

    /**
	 * 检验token
	 * @return boolean
	 */
	public static boolean verify(String token, String username) {
		...
	}

	/**
	 * 获得token中的属性
	 * @return token中包含的属性
	 */
	public static String getValue(String token, String key) {
		...
	}

	/**
	 * 生成token签名EXPIRE_TIME 分钟后过期
	 * 
	 * @param username
	 *            用户名
	 * @return 加密的token
	 */
	public static String createJWT(String userId) {
		...
	}
}

多Realm配置

用户密码认证和Jwt的认证需要不同的两个Realm，多Realm需要处理不同的Realm，获取到指定Realm的AuthenticationToken的数据模型。

• 实现ModularRealmAuthenticator的方法

public class MultiRealmAuthenticator extends ModularRealmAuthenticator {

    @Override
    protected AuthenticationInfo doAuthenticate(AuthenticationToken authenticationToken) 
    		throws AuthenticationException {
        assertRealmsConfigured();
        
        List<Realm> realms = this.getRealms()
                .stream()
                .filter(realm -> {
                    return realm.supports(authenticationToken);
                })
                .collect(Collectors.toList());
        
        return realms.size() == 1 ? this.doSingleRealmAuthentication(realms.get(0), authenticationToken) : 
        	this.doMultiRealmAuthentication(realms, authenticationToken);
    }
}

• AuthenticatingRealm中实现getAuthenticationTokenClass方法

public Class getAuthenticationTokenClass() {
    return JwtToken.class;
}

• 在SecurityManager中配置

@Bean(name = "securityManager")
public org.apache.shiro.mgt.SecurityManager defaultWebSecurityManager(@Autowired UserRealm 		userRealm,  @Autowired TokenRealm tokenValidateRealm) {
    securityManager.setAuthenticator(multiRealmAuthenticator());
    securityManager.setRealms(Arrays.asList(userRealm, tokenValidateRealm));
	...
    return securityManager;
}

整合Swagger

添加Swagger依赖

<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger2</artifactId>
    <version>2.9.2</version>
</dependency>

<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger-ui</artifactId>
    <version>2.9.2</version>
</dependency>

添加Swagger的配置

@Configuration
public class Swagger2Config {

    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(apiInfo())
                .select()
                .apis(RequestHandlerSelectors.basePackage("XXX"))
                .paths(PathSelectors.any())
                .build();
    }

    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("XXX")
                .description("经供参考")
                .version("1.0")
                .build();
    }
}

总结

在整个过程中，遇到的坑就是在Spring boot中Filter的自动注入，中间考虑有不使用注入的方式解决，即直接使用new JwtFilter()的方式，虽然也能解决问题，但是不是很完美，最终还是在网上找到解决方案。对Shiro的Filter链的执行过程加强了理解，能够使用自定的Filter解决实际问题。还有一个后续的问题，退出登录时的Jwt的token处理，它本身不能像Session一样，退出就清除，理论上只要没过期，就一直存在。可以考虑使用缓存，退出时清除即可，然后在校验时，先从缓存获取进行判断。