Spring Security默认登录页面代码位于哪里？

问：Spring Security默认登录页面代码位于哪里？

答：它是从此类生成的org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter。通过反编译spring-security-web-5.5.2.jar可查看源码如下：

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("SPRING_SECURITY_LAST_EXCEPTION");
                errorMsg = ex != null ? ex.getMessage() : "Invalid credentials";
            }
        }

        String contextPath = request.getContextPath();
        StringBuilder sb = new StringBuilder();
        sb.append("\n");
        sb.append("\n");
        sb.append("  \n");
        sb.append("    \n");
        sb.append("    \n");
        sb.append("    \n");
        sb.append("    \n");
        sb.append("    \n");
        sb.append("    \n");
        sb.append("    \n");
        sb.append("  \n");
        sb.append("  \n");
        sb.append("     
\n");
        if (this.formLoginEnabled) {
            sb.append("      
this.authenticationUrl + "\">\n");
            sb.append("        
Please sign in
\n");
            sb.append(createError(loginError, errorMsg) + createLogoutSuccess(logoutSuccess) + "        
\n");
            sb.append("          Username\n");
            sb.append("          this.usernameParameter + "\" class=\"form-control\" placeholder=\"Username\" required autofocus>\n");
            sb.append("        
\n");
            sb.append("        
\n");
            sb.append("          Password\n");
            sb.append("          this.passwordParameter + "\" class=\"form-control\" placeholder=\"Password\" required>\n");
            sb.append("        
\n");
            sb.append(this.createRememberMe(this.rememberMeParameter) + this.renderHiddenInputs(request));
            sb.append("        Sign in\n");
            sb.append("      
\n");
        }

        if (this.openIdEnabled) {
            sb.append("      
this.openIDauthenticationUrl + "\">\n");
            sb.append("        
Login with OpenID Identity
\n");
            sb.append(createError(loginError, errorMsg) + createLogoutSuccess(logoutSuccess) + "        
\n");
            sb.append("          Identity\n");
            sb.append("          this.openIDusernameParameter + "\" class=\"form-control\" placeholder=\"Username\" required autofocus>\n");
            sb.append("        
\n");
            sb.append(this.createRememberMe(this.openIDrememberMeParameter) + this.renderHiddenInputs(request));
            sb.append("        Sign in\n");
            sb.append("      
\n");
        }

        Iterator var7;
        Entry relyingPartyUrlToName;
        String url;
        String partyName;
        if (this.oauth2LoginEnabled) {
            sb.append("
Login with OAuth 2.0
");
            sb.append(createError(loginError, errorMsg));
            sb.append(createLogoutSuccess(logoutSuccess));
            sb.append("\n");
            var7 = this.oauth2AuthenticationUrlToClientName.entrySet().iterator();

            while(var7.hasNext()) {
                relyingPartyUrlToName = (Entry)var7.next();
                sb.append(" \n");
            }

            sb.append("
");
                url = (String)relyingPartyUrlToName.getKey();
                sb.append("");
                partyName = HtmlUtils.htmlEscape((String)relyingPartyUrlToName.getValue());
                sb.append(partyName);
                sb.append("");
                sb.append("
\n");
        }

        if (this.saml2LoginEnabled) {
            sb.append("
Login with SAML 2.0
");
            sb.append(createError(loginError, errorMsg));
            sb.append(createLogoutSuccess(logoutSuccess));
            sb.append("\n");
            var7 = this.saml2AuthenticationUrlToProviderName.entrySet().iterator();

            while(var7.hasNext()) {
                relyingPartyUrlToName = (Entry)var7.next();
                sb.append(" \n");
            }

            sb.append("
");
                url = (String)relyingPartyUrlToName.getKey();
                sb.append("");
                partyName = HtmlUtils.htmlEscape((String)relyingPartyUrlToName.getValue());
                sb.append(partyName);
                sb.append("");
                sb.append("
\n");
        }

        sb.append("
\n");
        sb.append("");
        return sb.toString();
    }