繼承自HttpServlet的類同時重寫了service()、doget()、dopost()方法，瀏覽器訪問時會執行哪個方法？

doget()、dopost()方法是HttpServlet類對Servlet接口service方法的重寫，所以繼承自HttpServlet類的Servlet類不需要重寫service()方法，只需要重寫doget()、dopost()方法，從Servlet生命周期中我們知道在調用init()方法初始化之后就調用service()方法，所以如果同時也重寫了service方法，如果沒有在service()方法中再調用doget()、dopost()方法，那么就只會調用service()方法。從HttpServlet類的源代碼中可以看出來service方法調用了doget()、dopost()等方法，如果我們重寫了service而沒有在方法中調用doget()、dopost()方法，那么只會調用service()方法。這部分也是最近剛開始學，有不足或者不對的地方歡迎補充。

以下是HttpServlet類的service()方法源代碼：

protected void service(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
{
    String method = req.getMethod();

    if (method.equals(METHOD_GET)) {
        long lastModified = getLastModified(req);
        if (lastModified == -1) {
            // servlet doesn't support if-modified-since, no reason
            // to go through further expensive logic
            doGet(req, resp);
        } else {
            long ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
            if (ifModifiedSince < lastModified) {
                // If the servlet mod time is later, call doGet()
                // Round down to the nearest second for a proper compare
                // A ifModifiedSince of -1 will always be less
                maybeSetLastModified(resp, lastModified);
                doGet(req, resp);
            } else {
                resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
            }
        }

    } else if (method.equals(METHOD_HEAD)) {
        long lastModified = getLastModified(req);
        maybeSetLastModified(resp, lastModified);
        doHead(req, resp);

    } else if (method.equals(METHOD_POST)) {
        doPost(req, resp);
        
    } else if (method.equals(METHOD_PUT)) {
        doPut(req, resp);
        
    } else if (method.equals(METHOD_DELETE)) {
        doDelete(req, resp);
        
    } else if (method.equals(METHOD_OPTIONS)) {
        doOptions(req,resp);
        
    } else if (method.equals(METHOD_TRACE)) {
        doTrace(req,resp);
        
    } else {
        //
        // Note that this means NO servlet supports whatever
        // method was requested, anywhere on this server.
        //

        String errMsg = lStrings.getString("http.method_not_implemented");
        Object[] errArgs = new Object[1];
        errArgs[0] = method;
        errMsg = MessageFormat.format(errMsg, errArgs);
        
        resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
    }
}