private void loadFile()

in client-adapter/common/src/main/java/com/alibaba/otter/canal/client/adapter/support/ExtensionLoader.java [308:397]
87 lines of code
20 McCabe index (conditional complexity)

    private void loadFile(Map<String, Class<?>> extensionClasses, String dir, ClassLoader classLoader) {
        String fileName = dir + type.getName();
        try {
            Enumeration<URL> urls;
            if (classLoader != null) {
                urls = classLoader.getResources(fileName);
            } else {
                urls = ClassLoader.getSystemResources(fileName);
            }
            if (urls != null) {
                while (urls.hasMoreElements()) {
                    URL url = urls.nextElement();
                    try {
                        try (BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), StandardCharsets.UTF_8))) {
                            String line;
                            while ((line = reader.readLine()) != null) {
                                final int ci = line.indexOf('#');
                                if (ci >= 0) line = line.substring(0, ci);
                                line = line.trim();
                                if (line.length() > 0) {
                                    try {
                                        String name = null;
                                        int i = line.indexOf('=');
                                        if (i > 0) {
                                            name = line.substring(0, i).trim();
                                            line = line.substring(i + 1).trim();
                                        }
                                        if (line.length() > 0) {
                                            Class<?> clazz = classLoader.loadClass(line);
                                            // Class<?> clazz =
                                            // Class.forName(line, true,
                                            // classLoader);
                                            if (!type.isAssignableFrom(clazz)) {
                                                throw new IllegalStateException(
                                                        "Error when load extension class(interface: " + type
                                                                + ", class line: " + clazz.getName()
                                                                + "), class " + clazz.getName()
                                                                + "is not subtype of interface.");
                                            } else {
                                                try {
                                                    clazz.getConstructor(type);
                                                } catch (NoSuchMethodException e) {
                                                    clazz.getConstructor();
                                                    String[] names = NAME_SEPARATOR.split(name);
                                                    if (names != null && names.length > 0) {
                                                        for (String n : names) {
                                                            if (!cachedNames.containsKey(clazz)) {
                                                                cachedNames.put(clazz, n);
                                                            }
                                                            Class<?> c = extensionClasses.get(n);
                                                            if (c == null) {
                                                                extensionClasses.put(n, clazz);
                                                            } else if (c != clazz) {
                                                                cachedNames.remove(clazz);
                                                                throw new IllegalStateException(
                                                                        "Duplicate extension " + type.getName() + " name "
                                                                                + n + " on "
                                                                                + c.getName() + " and "
                                                                                + clazz.getName());
                                                            }
                                                        }
                                                    }
                                                }
                                            }
                                        }
                                    } catch (Throwable t) {
                                        IllegalStateException e = new IllegalStateException(
                                                "Failed to load extension class(interface: " + type + ", class line: "
                                                        + line + ") in " + url
                                                        + ", cause: "
                                                        + t.getMessage(),
                                                t);
                                        exceptions.put(line, e);
                                    }
                                }
                            } // end of while read lines
                        }
                    } catch (Throwable t) {
                        logger.error("Exception when load extension class(interface: " + type + ", class file: " + url
                                     + ") in " + url,
                            t);
                    }
                } // end of while urls
            }
        } catch (Throwable t) {
            logger.error(
                "Exception when load extension class(interface: " + type + ", description file: " + fileName + ").",
                t);
        }
    }