这篇文章主要讲解了“spring security中的默认登录页源码分析”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“spring security中的默认登录页源码分析”吧！
springboot项目依赖
<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>在项目中随意编写一个接口，然后进行访问
@GetMapping("/")public String hello() { return "hello, spring security";}在tomcat默认端口8080，localhost:8080 下访问该接口，spring security会帮我们将路径重定向到默认的登录页
那么这个默认页是怎么来的呢？
原来Spring Security有一个默认的WebSecurityConfigurerAdapter，发现其中有一个init方法，于是在这个方法打了断点，在应用启动的时候进行跟踪。
跟踪getHttp()方法，this.disableDefaults变量默认为false，意味着将会执行applyDefaultConfiguration(this.http);方法。查看applyDefaultConfiguration方法
public void init(WebSecurity web) throws Exception { // 首先配置security要拦截的哪些http请求 HttpSecurity http = getHttp(); web.addSecurityFilterChainBuilder(http).postBuildAction(() -> { FilterSecurityInterceptor securityInterceptor = http.getSharedObject(FilterSecurityInterceptor.class); web.securityInterceptor(securityInterceptor); });}protected final HttpSecurity getHttp() throws Exception {if (this.http != null) {return this.http;}AuthenticationEventPublisher eventPublisher = getAuthenticationEventPublisher();this.localConfigureAuthenticationBldr.authenticationEventPublisher(eventPublisher);AuthenticationManager authenticationManager = authenticationManager();this.authenticationBuilder.parentAuthenticationManager(authenticationManager);Map<Class<?>, Object> sharedObjects = createSharedObjects();this.http = new HttpSecurity(this.objectPostProcessor, this.authenticationBuilder, sharedObjects);if (!this.disableDefaults) { // 默认的配置将会走这个分支applyDefaultConfiguration(this.http);ClassLoader classLoader = this.context.getClassLoader();List<AbstractHttpConfigurer> defaultHttpConfigurers = SpringFactoriesLoader.loadFactories(AbstractHttpConfigurer.class, classLoader);for (AbstractHttpConfigurer configurer : defaultHttpConfigurers) {this.http.apply(configurer);}}configure(this.http);return this.http;}查看applyDefaultConfiguration(this.http)方法，发现http对象new了一个DefaultLoginPageConfigurer对象属性，
private void applyDefaultConfiguration(HttpSecurity http) throws Exception { http.csrf(); http.addFilter(new WebAsyncManagerIntegrationFilter()); http.exceptionHandling(); http.headers(); http.sessionManagement(); http.securityContext(); http.requestCache(); http.anonymous(); http.servletApi(); http.apply(new DefaultLoginPageConfigurer<>()); http.logout();}查看DefaultLoginPageConfigurer类定义，发现它在初始化的同时，它也初始化了自己的2个私有成员变量，分别是DefaultLoginPageGeneratingFilter默认登录页面生成Filter,DefaultLogoutPageGeneratingFilter默认登录页面Filter, 名字起得很好，见名知意，我们马山知道这2个类的含义。
查看DefaultLoginPageGeneratingFilter的类成员变量，发现定义了一系列跟登录有关的成员变量，包括登录、登录等路径，默认的登录页面路径是"/login"
public class DefaultLoginPageGeneratingFilter extends GenericFilterBean { public static final String DEFAULT_LOGIN_PAGE_URL = "/login"; public static final String ERROR_PARAMETER_NAME = "error"; private String loginPageUrl; private String logoutSuccessUrl; private String failureUrl; private boolean formLoginEnabled; .....再结合类名思考，发现是个Filter类，那么它们应该都会重新Filter的doFilter(ServletRequest request, ServletResponse response, FilterChain chain)方法，我们查看一下DefaultLoginPageConfigurer类的``doFilter方法，果然，在doFilter`方法中发现了生成默认登录页面的方法。
private void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException { // 判断当前的请求是否被认证通过 boolean loginError = isErrorPage(request); boolean logoutSuccess = isLogoutSuccess(request); if (isLoginUrlRequest(request) || loginError || logoutSuccess) { // 当前请求认证失败的话，将会执行这个分支 String loginPageHtml = generateLoginPageHtml(request, loginError, logoutSuccess); response.setContentType("text/html;charset=UTF-8"); response.setContentLength(loginPageHtml.getBytes(StandardCharsets.UTF_8).length); response.getWriter().write(loginPageHtml); return; } chain.doFilter(request, response);}private String generateLoginPageHtml(HttpServletRequest request, boolean loginError, boolean logoutSuccess) { String errorMsg = "Invalid credentials"; if (loginError) { HttpSession session = request.getSession(false); if (session != null) { AuthenticationException ex = (AuthenticationException) session .getAttribute(WebAttributes.AUTHENTICATION_EXCEPTION); errorMsg = (ex != null) ? ex.getMessage() : "Invalid credentials"; } } String contextPath = request.getContextPath(); StringBuilder sb = new StringBuilder(); sb.append("<!DOCTYPE html>\n"); sb.append("<html lang=\"en\">\n"); sb.append(" <head>\n"); sb.append(" <meta charset=\"utf-8\">\n"); sb.append(" <meta name=\"viewport\" content=\"width=device-width, initial-scale=1, shrink-to-fit=no\">\n"); sb.append(" <meta name=\"description\" content=\"\">\n"); sb.append(" <meta name=\"author\" content=\"\">\n"); sb.append(" <title>Please sign in</title>\n"); sb.append(" <link href=\"https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css\" " + "rel=\"stylesheet\" integrity=\"sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M\" crossorigin=\"anonymous\">\n"); sb.append(" <link href=\"https://getbootstrap.com/docs/4.0/examples/signin/signin.css\" " + "rel=\"stylesheet\" crossorigin=\"anonymous\"/>\n"); sb.append(" </head>\n"); sb.append(" <body>\n"); sb.append(" <div class=\"container\">\n"); if (this.formLoginEnabled) { sb.append(" <form class=\"form-signin\" method=\"post\" action=\"" + contextPath + this.authenticationUrl + "\">\n"); sb.append(" <h3 class=\"form-signin-heading\">Please sign in</h3>\n"); sb.append(createError(loginError, errorMsg) + createLogoutSuccess(logoutSuccess) + " <p>\n"); sb.append(" <label for=\"username\" class=\"sr-only\">Username</label>\n"); sb.append(" <input type=\"text\" id=\"username\" name=\"" + this.usernameParameter + "\" class=\"form-control\" placeholder=\"Username\" required autofocus>\n"); sb.append(" </p>\n"); sb.append(" <p>\n"); sb.append(" <label for=\"password\" class=\"sr-only\">Password</label>\n"); sb.append(" <input type=\"password\" id=\"password\" name=\"" + this.passwordParameter + "\" class=\"form-control\" placeholder=\"Password\" required>\n"); sb.append(" </p>\n"); sb.append(createRememberMe(this.rememberMeParameter) + renderHiddenInputs(request)); sb.append(" <button class=\"btn btn-lg btn-primary btn-block\" type=\"submit\">Sign in</button>\n"); sb.append(" </form>\n"); } if (this.openIdEnabled) { sb.append(" <form name=\"oidf\" class=\"form-signin\" method=\"post\" action=\"" + contextPath + this.openIDauthenticationUrl + "\">\n"); sb.append(" <h3 class=\"form-signin-heading\">Login with OpenID Identity</h3>\n"); ...... return sb.toString();}我们发现generateLoginPageHtml(HttpServletRequest request, boolean loginError, boolean logoutSuccess)这个方法中使用了最原始的Servlet写html页面的方法，将登录页的html代码写到字符串中写出到前端展示。
感谢各位的阅读，以上就是“spring security中的默认登录页源码分析”的内容了，经过本文的学习后，相信大家对spring security中的默认登录页源码分析这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是编程网，小编将为大家推送更多相关知识点的文章，欢迎关注！
