Method init

java/org/apache/jasper/compiler/TagPluginManager.java:72–123

(ErrorDispatcher err)

    }

    private synchronized void init(ErrorDispatcher err) throws JasperException {
        if (initialized) {
            return;
        }

        String blockExternalString = ctxt.getInitParameter(Constants.XML_BLOCK_EXTERNAL_INIT_PARAM);
        boolean blockExternal;
        if (blockExternalString == null) {
            blockExternal = true;
        } else {
            blockExternal = Boolean.parseBoolean(blockExternalString);
        }

        TagPluginParser parser;
        Thread currentThread = Thread.currentThread();
        ClassLoader original = currentThread.getContextClassLoader();
        try {
            currentThread.setContextClassLoader(TagPluginManager.class.getClassLoader());

            parser = new TagPluginParser(ctxt, blockExternal);

            Enumeration<URL> urls = ctxt.getClassLoader().getResources(META_INF_JASPER_TAG_PLUGINS_XML);
            while (urls.hasMoreElements()) {
                URL url = urls.nextElement();
                parser.parse(url);
            }

            URL url = ctxt.getResource(TAG_PLUGINS_XML);
            if (url != null) {
                parser.parse(url);
            }
        } catch (IOException | SAXException e) {
            throw new JasperException(e);
        } finally {
            currentThread.setContextClassLoader(original);
        }

        Map<String,String> plugins = parser.getPlugins();
        tagPlugins = new HashMap<>(plugins.size());
        for (Map.Entry<String,String> entry : plugins.entrySet()) {
            try {
                String tagClass = entry.getKey();
                String pluginName = entry.getValue();
                Class<?> pluginClass = ctxt.getClassLoader().loadClass(pluginName);
                TagPlugin plugin = (TagPlugin) pluginClass.getConstructor().newInstance();
                tagPlugins.put(tagClass, plugin);
            } catch (Exception e) {
                err.jspError(e);
            }
        }
        initialized = true;
    }

    /**
     * Invoke tag plugin for the given custom tag, if a plugin exists for the custom tag's tag handler.