Shrio使用Jwt達到先後端分離

概述

先後端分離以後，由於HTTP自己是無狀態的，Session就無法用了。項目採用jwt的方案後，請求的主要流程以下：用戶登陸成功以後，服務端會建立一個jwt的token（jwt的這個token中記錄了當前的操做帳號），並將這個token返回給前端，前端每次請求服務端的數據時，都會將令牌放入Header或者Parameter中，服務端接收到請求後，會先被攔截器攔截，token檢驗的攔截器會獲取請求中的token，而後會檢驗token的有效性，攔截器都檢驗成功後，請求會成功到達實際的業務流程中，執行業務邏輯返回給前端數據。在這個過程當中，主要涉及到Shiro的攔截器鏈，Jwt的token管理，多Realm配置等。

Shiro的Filter鏈

Shiro的認證和受權都離不開Filter，所以須要對Shiro的Filter的運行流程很清楚，才能自定義Filter來知足企業的實際須要。另外Shiro的Filter雖然原理都和Servlet的Filter類似，甚至都最終繼承相同的接口，可是實際仍是有些差異。Shiro中的Filter主要是在ShiroFilter內，對指定匹配的URL進行攔截處理，它有本身的Filter鏈；而Servlet的Filter和ShiroFilter是同一個級別的，即先走Shiro本身的Filter體系，而後纔會委託給Servlet容器的FilterChain進行Servlet容器級別的Filter鏈執行

分析Shiro的默認Filter

在Shiro和Spring Boot整合過程當中，須要配置ShiroFilterFactoryBean，該類是ShiroFilter的工廠類，並繼承了FactoryBean接口。能夠從該接口的方法來分析。該接口getObject獲取一個實例，按照邏輯，發現調用createFilterChainManager，並建立默認的Filter(按照命名猜想Map<String, Filter> defaultFilters = manager.getFilters())。

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

    private Map<String, String> filterChainDefinitionMap; 

    /**
     *
     * 該工廠類生產的產品類
     */
    public Object getObject() throws Exception {
        if (instance == null) {
            instance = createInstance();
        }
        return instance;
    }

    protected FilterChainManager createFilterChainManager() {
        //建立默認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);
        }
        //建立FilterChainManager
        FilterChainManager manager = createFilterChainManager();

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

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

在DefaultFilterChainManager中addDefaultFilters來添加默認的Filter，DefaultFilter爲一系列默認Filter的枚舉類。

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);
        }
    }

     /**
     *
     * 建立默認的Filter
     */
    protected void addDefaultFilters(boolean init) {
        for (DefaultFilter defaultFilter : DefaultFilter.values()) {
            addFilter(defaultFilter.name(), defaultFilter.newInstance(), init, false);
        }
    }
    ...
}

從這個枚舉類中能夠看到以前添加的共有11個默認Filter，它們的名字分別是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的繼承體系分析

• NameableFilter給Filter起個名字，若是沒有設置，默認名字就是FilterName。

• OncePerRequestFilter用於防止屢次執行Filter；也就是說一次請求只會走一次攔截器鏈；另外提供 enabled 屬性，表示是否開啓該攔截器實例，默認 enabled=true 表示開啓，若是不想讓某個攔截器工做，能夠設置爲 false 便可。

• AdviceFilter提供了AOP風格的支持。preHandler：在攔截器鏈執行以前執行，若是返回true則繼續攔截器鏈；不然中斷後續的攔截器鏈的執行直接返回；能夠進行預處理（如身份驗證、受權等行爲）。postHandle：在攔截器鏈執行完成後執行，後置處理（如記錄執行時間之類的）。afterCompletion：相似於AOP中的後置最終加強；即無論有沒有異常都會執行，能夠進行清理資源（如接觸 Subject 與線程的綁定之類的）。

• PathMatchingFilter內置了pathMatcher的實例，方便對請求路徑匹配功能及攔截器參數解析的功能，以下所示，對匹配的路徑執行isFilterChainContinued的邏輯，若是都沒配到，則直接交給攔截器鏈。

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()) {
        //對匹配路徑進行處理
        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提供了訪問控制的基礎功能，isAccessAllowed訪問經過，則交給攔截器鏈，不經過則執行onAccessDenied來肯定交給攔截器仍是本身處理

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

• AuthenticationFilter認證Filter的基類，通常在isAccessAllowed中執行認證邏輯，另外該Filter提供登陸成功後跳轉的功能

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的子類，提供了executeLogin通用邏輯，一般由子類來實現protected abstract AuthenticationToken createToken(ServletRequest request, ServletResponse response)該方法，而後執行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中添加自定義的Filter

從上面源碼分析，知道了Shiro會提供11個默認的Filter，也是按照攔截器模式交由FilterChainManager來管理Filter，並最終返回SpringShiroFilter。因此添加自定義的Filter，主要有三步。

• 實現本身的Filter

以下實現了本身的JwtFilter，主要邏輯能夠參考FormAuthenticationFilter。JwtFilter主要是對前端的Api進行校驗，檢驗失敗，則拋出異常信息，不給攔截器鏈處理。

@Slf4j
public class JwtFilter extends AuthenticatingFilter {   
    private static final String TOKEN_NAME = "token";
    
    /**
     * 建立令牌
     */
    @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);     
    }
    
    /**
     * 獲取令牌
     * @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;
    }
 
    /**
     * 未經過處理
     * @param servletRequest
     * @param servletResponse
     * @return
     * @throws Exception
     */
    @Override
    protected boolean onAccessDenied(ServletRequest servletRequest, ServletResponse servletResponse) throws Exception {
        return executeLogin(servletRequest, servletResponse);
    }

    /**
     * 登陸失敗執行方法
     * @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;
    }
    ...
}

• 將Filter添加到Shiro中

將自定義的Filter添加到Shiro，並要指定的匹配路徑。

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自動幫咱們註冊了咱們的Filter(Filter是註冊到整個Filter鏈，而不是Shiro的Filter鏈)，可是在Shiro中，咱們須要本身實現註冊，可是又須要Filter實例存在於Spring容器中，以便能使用其餘衆多服務(自動注入其餘組件……)。因此須要取消Spring Boot的自動注入Filter。能夠採用以下方式：

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

Jwt整合

使用Jwt須要咱們提供對token的建立，校驗和獲取token中信息的方法。網上有不少，能夠借鑑，並且token中也能夠存一些其餘數據。

public class JwtUtil {

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

    /**
     * 得到token中的屬性
     * @return token中包含的屬性
     */
    public static String getValue(String token, String key) {
        ...
    }

    /**
     * 生成token簽名EXPIRE_TIME 分鐘後過時
     * 
     * @param username
     *            用戶名
     * @return 加密的token
     */
    public static String createJWT(String userId) {
        ...
    }
}

多Realm配置

用戶密碼認證和Jwt的認證須要不一樣的兩個Realm，多Realm須要處理不一樣的Realm，獲取到指定Realm的AuthenticationToken的數據模型。

• 實現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中實現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依賴

<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("經供參考")
                .version("1.0")
                .build();
    }
}

總結

在整個過程當中，遇到的坑就是在Spring boot中Filter的自動注入，中間考慮有不使用注入的方式解決，即直接使用new JwtFilter()的方式，雖然也能解決問題，可是不是很完美，最終仍是在網上找到解決方案。對Shiro的Filter鏈的執行過程增強了理解，可以使用自定的Filter解決實際問題。還有一個後續的問題，退出登陸時的Jwt的token處理，它自己不能像Session同樣，退出就清除，理論上只要沒過時，就一直存在。能夠考慮使用緩存，退出時清除便可，而後在校驗時，先從緩存獲取進行判斷。