如何将GoogleSpellChecker与SpringMVC与ServletWrappingController集成

Question

目前，我的应用程序使用SpringMVC进行所有控制器映射。我正在尝试实现一个tinyMCE拼写检查，它包括一个Servlet，我不确定如何在不修改该文件本身的情况下正确集成该Servlet。我想避免修改，这样如果我们以后有新版本，我们就可以了。

Servlet看起来像...

public abstract class TinyMCESpellCheckerServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    private static Logger logger = Logger.getLogger(TinyMCESpellCheckerServlet.class.getName());

    private static final String MAX_SUGGESTIONS_COUNT_PARAM = "maxSuggestionsCount";
    private static final String PRELOADED_LANGUAGES_PARAM = "preloadedLanguages";

    private static final String DEFAULT_LANGUAGE = "en";
    private static final String GET_METHOD_RESPONSE_ERROR = "This servlet expects a JSON encoded body, POSTed to this URL";

    private static String DEFAULT_PRELOADED_LANGUAGES = "en-us";

    private enum methods {
        checkWords, getSuggestions
    }

    private int maxSuggestionsCount = 25;


    @Override
    public void init() throws ServletException {
        super.init();
        preloadSpellcheckers();
        readMaxSuggestionsCount();
    }

    private void preloadSpellcheckers() throws ServletException {
        String preloaded = getServletConfig().getInitParameter(PRELOADED_LANGUAGES_PARAM);
        if (preloaded == null || preloaded.trim().length() == 0) {
            preloaded = DEFAULT_PRELOADED_LANGUAGES;
        }

        String[] preloadedLanguages = preloaded.split(";");
        for (String preloadedLanguage : preloadedLanguages) {
            try {
                preloadLanguageChecker(preloadedLanguage);
            } catch (SpellCheckException e) {
                //wrong servlet configuration
                throw new ServletException(e);
            }
        }
    }

    protected abstract void preloadLanguageChecker(String preloadedLanguage) throws SpellCheckException;

    /**
     * This method look for the already created SpellChecker object in the cache, if it is not present in the cache then
     * it try to load it and put newly created object in the cache. SpellChecker loading is quite expensive operation
     * to do it for every spell-checking request, so in-memory-caching here is almost a "MUST to have"
     *
     * @param lang the language code like "en" or "en-us"
     * @return instance of SpellChecker for particular implementation
     * @throws SpellCheckException if method failed to load the SpellChecker for lang (it happens if there is no
     *                             dictionaries for that language was found in the classpath
     */
    protected abstract Object getChecker(String lang) throws SpellCheckException;


    private void readMaxSuggestionsCount() throws ServletException {
        String suggestionsCountParam = getServletConfig().getInitParameter(MAX_SUGGESTIONS_COUNT_PARAM);
        if (suggestionsCountParam != null && suggestionsCountParam.trim().length() > 0) {
            try {
                maxSuggestionsCount = Integer.parseInt(suggestionsCountParam.trim());
            } catch (NumberFormatException ex) {
                //wrong servlet configuration, possibly a typo
                throw new ServletException(ex);
            }
        }
    }


    /**
     * @see javax.servlet.Servlet#destroy()
     */
    public void destroy() {
        super.destroy();
        //remove unused objects from memory
        clearSpellcheckerCache();
    }

    protected abstract void clearSpellcheckerCache();


    /**
     * GET method is not supported
     * @see HttpServlet#doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        setResponeHeaders(response);
        PrintWriter pw = response.getWriter();
        pw.println(GET_METHOD_RESPONSE_ERROR);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        setResponeHeaders(response);
        try {
            JSONObject jsonInput = readRequest(request);

            String methodName = jsonInput.optString("method");
            if (methodName == null || methodName.trim().equals("")) {
                throw new SpellCheckException("Wrong spellchecker-method-name:" + methodName);
            }

            JSONObject jsonOutput = new JSONObject("{'id':null,'result':[],'error':null}");
            switch (methods.valueOf(methodName.trim())) {
                case checkWords:
                    jsonOutput.put("result", checkWords(jsonInput.optJSONArray("params")));
                    break;
                case getSuggestions:
                    jsonOutput.put("result", getSuggestions(jsonInput.optJSONArray("params")));
                    break;
                default:
                    throw new SpellCheckException("Unimplemented spellchecker method {" + methodName + "}");
            }

            PrintWriter pw = response.getWriter();
            pw.println(jsonOutput.toString());

        } catch (SpellCheckException se) {
            logger.log(Level.WARNING, se.getMessage(), se);
            returnError(response, se.getMessage());
        } catch (Exception e) {
            logger.log(Level.WARNING, e.getMessage(), e);
            returnError(response, e.getMessage());
        }

        response.getWriter().flush();
    }
.....

Answer 1

看看ServletWrappingController（javadoc）

Spring控制器实现，它封装了它内部管理的servlet实例。这种封装的servlet在该控制器之外是未知的；这里介绍了其整个生命周期（与ServletForwardingController不同）。

通过Spring的调度基础设施调用现有servlet非常有用，例如将Spring HandlerInterceptors应用于其请求。

在Spring上下文中配置其中一个，使用TinyMCE servlet类名进行配置，并使用SimpleRhlHandlerMapping进行映射。

ServletForwardingController也很有用，但略有不同。